Why Gravity is NOT a Force

  • Am Vor year

    VeritasiumVeritasium

    The General Theory of Relativity tells us gravity is not a force, gravitational fields don't exist. Objects tend to move on straight paths through curved spacetime. Thanks to Caséta by Lutron for sponsoring this video. Find out more at: www.lutron.com/veritasium

    Huge thanks to Prof. Geraint Lewis for hours of consulting on this video so I could get these ideas straight in my own brain. Check out his DE-film channel: ve42.co/gfl or his books: ve42.co/GFLbooks

    Amazing VFX, compositing, and editing by Jonny Hyman
    2D animations by Ivàn Tello
    Filmed by Steven Warren and Raquel Nuno
    Special thanks to Petr Lebedev for reviews and script consultation
    Music by Jonny Hyman and from Epidemic Sound epidemicsound.com

    Rocket made by Goodnight and Co.
    Screen images in rocket by Geoff Barrett

    Slow motion rocket exhaust footage from Joe Barnard at BPS.Space
    de-film.com/ch-UCILl...

Veritasium
Veritasium

Here's a question I've seen a lot in comments: OK, I'm accelerating up but then shouldn't someone on the other side of the globe fall off? No, here's why: Either watch again from 8:28 or read what I've written below... Spacetime is curved - it curves the opposite direction on the other side of the Earth.  Neither us on this side of the Earth nor they on the other side are changing our spacial coordinates - we're not moving up, they're not moving down - Earth isn't flying into one of us. BUT we both ARE accelerating. In curved spacetime you have to accelerate just to remain stationary. The traditional definition of acceleration is something changing its velocity. In general relativity you have to embrace a new definition of acceleration: it means deviating from a geodesic - not going on a straight line path through spacetime. Near the Earth a geodesic is a parabola so unless you're moving in a parabolic arc (like on a zero-g plane) you are accelerating. This definition is the same as the old one  so if you're accelerating in deep space then your velocity is changing. *BUT*... if you are near a large mass you are in curved spacetime, now acceleration  your velocity is changing. You can stay stationary relative to Earth's surface and still be accelerating. This is because your acceleration should be measured not relative to the Earth's surface but relative to free-falling objects - they are inertial observers. Imagine this - I'm in deep space and I make horizontal rows and rows of stationary golf balls. Then I hop in my rocket and accelerate up through them. Just think about what that looks like. Now my rocket is back on Earth just sitting there. I freeze time for a sec and make horizontal rows and rows of golf balls up into the atmosphere. Now unfreeze time. What do you see? If you just look at the golf balls and the rocket ship it looks the same as the situation in space where the golf balls were stationary and the rocket was accelerating. Einstein's point was the golf balls have the better claim as the "stationary" thing since their experience is just like the golf balls in deep space - no forces experienced. The rocket on Earth is just like the rocket in space. It feels a force and hence an acceleration.

Vor year
Ju Don
Ju Don

But doesn't the fact that there's no such thing as stationary in our universe since everything in it is accelerating dispel that theory? I mean since absolutely everything and everyone is accelerating through space with the expansion of the universe what makes the free falling person or the person out in space's experience of being stationary more valid than mine?

Vor 9 Monate
Aditya Pereira
Aditya Pereira

I cant explain what I understood or how much I related to the information you shared.. It is however a spiritual experience when u find someone thinking alike for a rookie..

Vor 10 Monate
Keldren Raze
Keldren Raze

@Steve Wright honestly it doesn't exist.. it's just observing, measuring and predicting change. He only mentioned moving through time as a helix of motion to simulate the earth also orbiting the sun even as an object orbits the earth.. so adding the concept of "moving through time" would change the shape of the movement 3 dimensionally, it has no further significance in this instance.

Vor 11 Monate
The Action Lab
The Action Lab

This video is a masterpiece. The best explanation of gravity on the internet currently.

Vor year
Shriniwas Bhoite
Shriniwas Bhoite

Yep

Vor Monat
Fiorintino Cogin
Fiorintino Cogin

The lack thereof

Vor 2 Monate
Saurabh
Saurabh

Case I --> An observer falling, see the person standing on ground accelerating upwards. Case II --> An observer standing on ground, see the person falling, accelerating downwards. Therefore, Observations are different when we see from different perspective. So, how can you tell which perspective is the correct one. We find the Newtonian physics true because we are standing on Earth. But as we expand in space, we should change our perspective

Vor 5 Monate
Ângelo Zanatta
Ângelo Zanatta

Explanation of what? 😂

Vor 8 Monate
Mingash-منقاش
Mingash-منقاش

The two great scientists meet. ⚡️🤝🔥

Vor 8 Monate
1 laymans terms
1 laymans terms

Ok, interesting, so two questions based on that. 1. What effect would this have on an object passing exactly in the middle between two masses that are exact masses ? Would nothing change, with no curve, or would it accelerate you similar to a cork flying from a Champaign bottle ? 2. Is it only the G's of the accelerating floor underneath you that would kill you, or would you still be effected if you were somehow accelerating alone in space, and through some miracle, able to do it naked, not being effected by the lack of air and ravages of space ?

Vor 3 Tage
Prakhar Maurya
Prakhar Maurya

I never saw anyone explain GENERAL RELATIVITY better than this. Totally mind-blowing video.

Vor 3 Tage
Web Citizen
Web Citizen

@arkine11 It is impossible to comprehend (lat. comprehendere: to wrap around) an impossibility. Space and time cannot curve. This is just a theory designed to explain some equations which will later be superseded by a better theory without idiotic philosophical implications. Or you can hold to the Ether model which has great explanatory power and no idiotic and evidently stupid implications.

Vor 21 Stunde
arkine11
arkine11

It's still so complex to wrap the brain around, but it really got my thought juices flowing! Love it.

Vor Tag
bikeboy66
bikeboy66

I keep coming back to this superb video - it is such a beautiful and accessible explanation to laypeople like myself of what the genius of Einstein brought to the world. You just will not find a better video on gravity than this. Thankyou Veritasium!

Vor 3 Tage
Nichael Cramer
Nichael Cramer

Gravity is a “virtual force” in precisely the same way that centrifugal force is a “virtual force” I.e. the source of the “confusion”(as it were) is that you mistake the area around you as an inertial frame.

Vor 3 Tage
indifferent legume
indifferent legume

Wouldnt it be a natural reaction?

Vor 14 Stunden
Wave
Wave

"Gravity is an illusion" flat earthers: "WRITE THAT DOWN WRITE THAT DOWN"

Vor year
1111xyz
1111xyz

Just like our reality.

Vor Tag
Jeremiah Noar
Jeremiah Noar

I couldn't even imagine explaining the mechanics of gravity to one of them. They refuse to even accept the watered down version of it you learn in grade school. lol

Vor 13 Tage
hiren Drall
hiren Drall

@Alex Wilson lol

Vor 6 Monate
Blidea
Blidea

The fact that flat earthers' theory about the acceleration force moving us """"""up"""""" is actually right confuses me.

Vor 8 Monate
NYCFenrir
NYCFenrir

@Wave A flat earther legit reference this video to me and said gravity doesn't exist because it's apparent. Also said the earth is flat because the rocket is flat in the video.

Vor 9 Monate
Aibak Agbariya
Aibak Agbariya

A good simulation would be Imagining the space time fabric as a pool of water , I am not a physicist but accelerating heavy round object inside a pool should bend the liquid in a relative radius to the object weight and speed(space time fabric ) ,which will cause geodesics in the pool (deviation of space time fabric) ,now by dropping a light weight object into our geodesics , we should have our heavy object pulling the other object closer to it until it hits it and turn into stationary state (synchronized speed ,with the light weight object sticking to the other) Please one more video of this topic like to get attention

Vor 2 Monate
Space Pirate
Space Pirate

Wish i seen an illustration

Vor 10 Stunden
Melody
Melody

Every time someone points out that the stretchy fabric demo i always am mindblown that we just accepted without issue a explanation for gravity that requires gravity to work

Vor 2 Monate
VisionThing
VisionThing

@Stephen Scharf He almost makes it sound like Luminiferous aether. Come to think one of his videos talked about light maybe traveling at different speeds in different directions… I’m starting to think he believes in it.

Vor 9 Stunden
Andrea Cristiano
Andrea Cristiano

​@David Mudry because when you move at constant speed and emit light, light is traveling at your same constant speed. So it doesn't flex after the emission. But when you accelerate you are moving at x speed and emit light that moves in your same direction at x speed, but then you accelerate so you are moving at x+1 but light is still moving at x in that direction. So it lags behind. Hope it is right...

Vor 3 Tage
CabanaCaseda
CabanaCaseda

@Stephen Scharf what makes you think that it is mediated through a field?

Vor 8 Tage
BuzZ Sword
BuzZ Sword

@David Mudry i also want to know 🥲

Vor 10 Tage
Night Tow
Night Tow

So I've seen inertial frame of reference from our son, and inertial frame of reference from I believe it was perhaps the center of our galaxy, observing our solar system pass by. My question is, can a solid Mass for instance rocket man, be stationary in reference to the universe? Is stationary in reference to the universe even possible? Can you have an inertial frame of reference that is not tied to anything? Such as a spot in the emptiness outside of the known universe? Is the universe actually moving through whatever is outside of the universe? How far of the chain can you go with this inertial frame of reference? If we step outside of the bubble that is our universe, is this vast emptiness also moving somewhere? And can an observer from any reference anywhere find a fixed point that is not moving in or outside of this universe? Does SpaceTime exist outside of our known universe? And if it does is our universe bending that SpaceTime attracting whatever is outside of our universe towards us?

Vor 22 Stunden
Mr Naseem
Mr Naseem

The amount of mind Einstein used for getting up to these conclusions and reasoning is pure out of the box and we must educate kids to be like what Einstein did. Assume every thing you know and read so far as wrong. Not claim like everything is wrong but question the accuracy of everything.

Vor 2 Tage
bifimi
bifimi

Aha, so i must educate my kids to be like Einstein. No problem. After that I will educate my wife to turn into a Marylin Monroe. By the way, please better stay away from children.

Vor 17 Stunden
Mike CR
Mike CR

I'll assign credit when Einstein's theories are laws.

Vor Tag
Shadon_official
Shadon_official

I will make sure to do that. Thank you!

Vor Tag
Ananya Ravikumar
Ananya Ravikumar

On a lighter note, this means that the apple didn’t fall on Newton’s head. He accelerated right into it.

Vor year
Joshua Espinoza
Joshua Espinoza

@Terra Firma im not a physicist, im an engineer. Ive always been told that friction and air resistance are negligible.

Vor 13 Stunden
Patrik6920
Patrik6920

@The Brahmnic Boy well actually bothe the apple and newtons head moved in a spiral....and so did earth....still did the apple fell on his head or did he got pushed into the apple by earth?...🙃

Vor 21 Stunde
Terra Firma
Terra Firma

Your almost correct Josh. When the tree branch lets loose the apple, the friction of the air is pushing the apple toward the ground. All the air pressure above the apple is in a column of air stationary to the earths travel toward it, exerting the frictional resistence preventing the apple from maintaining its accelaration with the tree and the earth. 😉

Vor Tag
Joshua Espinoza
Joshua Espinoza

the apple, newton, and eath, are all accelerating. the earth has a higher mass-energy, and therefore distorts spacetime more than newton or the apple. newton and the apple have less mass energy, and distort spacetime less than the earth. since all three objects are relatively close to eachother, the 2 smaller objects fall into the distortion created by the larger object, ie, earth. newton was "at rest". he had accelerated into the earth until making direct physical contact, upon which the normal force pushed him back. the normal force is acting upon newton, and he can no longer accelerate faster than the earth, unless the earth moves out of the way, which it will not, therefore he will match the speed of the earth and stop accelerating. since he has stopped accelerating, relative to the earth, he is an object at rest. the apple is connected to the tree branch, but is not making direct contact with the object of superior mass-energy, ie, it is not touching the earth. the apple wants to accelerate towards the earth, but is being physically held back by the tree branch, which itself is part of the tree. the tree is touching the earth, and the normal force prevents it from accelerating further, as it does to newton. the tree touches the earth, the tree touches the apple, the apple is the tree, and does not currently exist. at one point in time, the apple has separated from the tree branch, and the tree, and therefore the earth. the apple is no longer making contact with the earth in any way shape or form, and has no normal force to keep it up. the apple has less mass-energy than the earth, and therefore will fall into the earth's space-time distortion. the apple begins accelerating relative to the earth, in order to meet it, since it is no longer at rest, because it is not being held back by the normal force. unfortunately for newton, he is physically obstructing the path from the apple to the earth. the apple continues accelerating, and encounters newton's head. newton is at rest, connected to the earth, and the apple has just connected with newton. the apple is pushed back by the normal force, and stops accelerating, since it is now connected to the earth. in other words, the apple has just hit newton's head. the end. in other news; the missile knows where it is

Vor 3 Tage
Anonymous Individual
Anonymous Individual

If you're falling down a gravity well staying still on a curved geodesic then the earth is accelerating towards you you could measure the change in its velocity so you could say that its actually a non inertial frame of reference even though objectively an observer on the surface wouldn't measure any change in motion either so you could alternatively argue that what's fake is not gravitational acceleration but the idea of a universally agreeable inertial frame of reference which must always be defined relative to a surrounding environment. a guy falling off a roof sees you through a window accelerating upwards relative to the flat space time defined from his frame of reference but he could say the same exact thing about everything else in your own frame including the rest of the planet that it's all accelerating towards him and non inertial even though it is to itself. you say you can accelerate without your spatial coordinates changing but you only remain in the same spot from your own viewpoint relative to the falling dude who says you're accelerating and hes not you are changing in spatial coordinates if he's the origin of the grid 0,0,0. you're definitely moving away from him but you can say fairly accurately that relative to everything in the room you're in you're not accelerating and so the curvature of spacetime is zero so whether or not space time geodesics are curved or flat could be said to be a matter of perspective space is flowing downwards and you up and you're both not moving at all. inertial mass and gravitational mass are probably mathematically identical even though the seem superficially dissimilar concepts because they are physically identical they have a shared real cause and genuinely are equivalent. whether a charge emits electromagnetic radiation may depend on what frame of reference you conduct the test in one stationary relative to the charge or one accelerating relative to it if that's not the case and the free falling charge doesn't emit EM waves while the stationary one does then that implies a universal inertial flat space frame of reference and an objective curvature of space time which doesn't depend on the view of the observer which seems pretty reasonable to me except objects have relativistic masses which must affect how they curve space time to be different between two inertial frames of reference with varying velocities so its not universally agreeable across all velocities from 0 to c although there's still a shared objective rest mass.

Vor 3 Tage
Larry Boles
Larry Boles

The Gravity Recovery and Climate Experiment (GRACE) consists of two satellites that can detect gravitational changes across the Earth. Also these changes can be presented as gravity anomaly temporal variations. The Gravity Recovery and Interior Laboratory (GRAIL) also consisted of two spacecraft orbiting the Moon, which orbited for three years before their deorbit in 2015.

Vor 8 Tage
Aliabbas Zoher
Aliabbas Zoher

My mind was blown the first time I saw this video. Looking at similar videos over a year, I feel this is still the best explanation and representation of gravity and how it works

Vor 25 Tage
Hugo
Hugo

I've just watched your other great video on the speed of light and whether this is a constant speed in both / all directions. Can you please explain to me why the experiment mentioned in this video at circa 13:00 couldn't be used to determine if light was moving faster in one direction to another? I.e, by shining the light through the accelerating rocket ship from 2 opposite directions and seeing if the difference in where the light is measured inside the ship is equal (or not) on both sides. Excuse the wordy question but I have no science background, hope I've made sense.

Vor 2 Monate
Beyond Batcoif
Beyond Batcoif

If C is different in different directions, one wall of the ship is not where you observe it to be, because you are observing the different speed light from the opposing direction light. The experiment would show the same both directions for different reasons.

Vor Monat
Neutronplant
Neutronplant

The difference would simply be too small to notice or measure.

Vor Monat
Morpheus
Morpheus

When mountain climbing, try not to become an inertial observer.

Vor year
James Markov
James Markov

How about cleaning the gutters on the house?

Vor Tag
RedEye
RedEye

First PERSON anyway.

Vor 2 Tage
DDDestrier
DDDestrier

I didn’t understand

Vor 10 Tage
Soham
Soham

@Soham Acharya Ayo that's my name

Vor 13 Tage
michael hole
michael hole

But if you do, stay one

Vor 16 Tage
The Colonel
The Colonel

As I go through my Physics own adventure, I am finding out how little we really know about physics of the universe. Example: Our knowledge of the "behavior" of electricity on the earth is quite well known and is constantly tested and revalidated; however, our knowledge of how these observations occur at the quantum level are a bit sketchy - to say the least. So, in a sense, gravity is a Newtonian behavioral concept to "make the physics work" in a very specific domain where we do not have inertial observers. This is no criticism of Newtonian Mechanics, but a cautionary tale if one decides to take our limited observations (and their calculations) somewhere else.

Vor 3 Tage
bcfc ireland
bcfc ireland

gravity is a Newtonian behavioral concept actually newton distanced himself from it, it was much later it was asigned to him..but if you read his works he was not convinced.

Vor Tag
SuperiorMind
SuperiorMind

They're turning physics into a religion. Btw - gravity is indeed a force. You go anywhere in space and you'll see stars in all directions. That's because forces with visible frequency from all around you pass through you (equally from all sides [equilibrium of influence]) - [not to mention non-visible frequency [& non-frequency] force coming from stars]. If you block some of the force coming at you from a side, you'll be pushed toward the thing blocking(delaying) some of the force. Gravity really is quite simple. Magnetism is a bit more complex (but still simple)... again because many ideas in our model are nonsense. The model of force (aka light) is also screwed up and part of what's holding us humans from advancing. As long as ppl keep ignoring evidence and accepting what they're taught blindly, it'll henceforth be more like a religion than actual science.

Vor 2 Tage
Heather Anderson-Duncan
Heather Anderson-Duncan

Wow, I have watched so many videos on general relativity and the way the audience 'discovers' relativity with you helps me get it. Well done sir.

Vor 9 Tage
Brendan Townsend
Brendan Townsend

Perhaps we're coming full-circle on the question of why the outer expanse of the universe appears to be accelerating away from us, when conventional physics suggests that it should be slowing down. Anything under 'gravitational' influence is proceding through time faster to a remote observer, but the effect is merely the delta between the two - such as people on the earth's surface appearing to slow down when observed by an atronaut floating in space. Of-course we're only talking of picoseconds, and we all exist in a "gravitational soup". Now if we're to believe in a 'big bang', then the spacial mass density reduces towards the outermost regions of the universe - ergo, increased delta to observers contained within that gravitational soup. So, should we not therefore expect such observations in satisfying the laws of general relativity?

Vor Tag
Terasent Terasent
Terasent Terasent

Hello my fellow humans have a thought I would like to share, gravity and acceleration are thought to be the same thing? And putting aside centrifical force and a body in it feeling a similar force like gravity because of spin, now if you are accelerating up feeling the force of gravity pushing up on your feet your limit would be up to almost the point of the speed of light and you could not accelerate any further because our beloved Eisenstein has shown us a mass can not surpass light speed and thus the up ward push would stop, no more gravity, but a large mass bending time space causing the effect of gravity is almost forever a constant, and that’s the difference one has a limit the other is constant so are they exactly the same thing or the effect is the same but fundamentally they are different deep in the details? Cheers Nick

Vor 2 Tage
Raj Datta
Raj Datta

But the question is, why does space time curve around massive objects?

Vor year
VisionThing
VisionThing

@Valentino Nathan It was a joke ;(

Vor 6 Stunden
Valentino Nathan
Valentino Nathan

@VisionThing gravity is the curvature, now why does it curve?

Vor 6 Stunden
VisionThing
VisionThing

Because of… gravity!

Vor 8 Stunden
Valentino Nathan
Valentino Nathan

maybe matter is "anti-spacetime" ?

Vor Monat
sìN
sìN

@Ch Tη thanks for the golden explanation man

Vor 2 Monate
Eugene Bunt
Eugene Bunt

Einstein explained gravity over one hundred years ago: He said it was warped space-time and told where to look for it, the bending of light in a gravitational field. He explained the bending of light was caused by space rising from the surface of the Sun, as space rises light coming from the background constellation passing close to the surface of the Sun, enters the rising space at a higher level on the far side, and as the space rises it exits lower on our side as it travels toward us making, the images of the stars appear as if they are at a wider angle away from the Sun (the gravitation lens effect). He also said time slows in the presence of mass, with rising space coming from the core of the Earth (our gravity source) we move farther, faster toward the gravity source than matter moves away from it. With matter moving toward the core, matter applies pressure on the core, anything put under pressure radiates heat (long-wave energy) in essence elongating the fabric of space vertically to the planet's surface which allows light to make longer jumps per second. Change in momentum lags behind the change in velocity. Matter does not pull on matter, we are decelerating on the planet's surface at the rate of acceleration that the core is expanding new space as the surface pressure is heating the core. Gravity is a change in uniform motion.

Vor Monat
Kiran Sunny
Kiran Sunny

What I'm curious about is whether spacetime is curved all over the universe, at least ever so slightly, meaning there isn't actually any point in the universe where spacetime is NOT curved?

Vor 28 Tage
Patrik6920
Patrik6920

@TeamSprocket idd very true, it can be esier understand if u think of an object propagating a field according to the propagation of waves...it for example take a sound wave to spread (can be easir get if using a not to complex analogy).. ..waves intersects...and so does gravity and gravitaional waves...emty space can idd be warpedd in very strenge ways...Einstein calculated this and foorsee it, and it was later proven...

Vor 2 Tage
Andrea Cristiano
Andrea Cristiano

@Neema Zadeh I believed the gravity field to be different from zero in every place in space. So astronauts are falling, even if slowly. This video say that there is no field, and that they are not falling. So basically everything contradicts my beliefs, or, better, is the same situation but looking at the other side of the coin

Vor 3 Tage
Neema Zadeh
Neema Zadeh

@Andrea Cristiano this sounds about right, though. "Falling" is just following the "straight line" of spacetime. I'm curious what you learned that contradicted this

Vor 3 Tage
Andrea Cristiano
Andrea Cristiano

I always thought falling we feel like an astronaut floating because he is not floating. He is actually falling like us, but have no planet as reference to understand it. And then I see this video that tells me I understood everything wrong!

Vor 3 Tage
Neema Zadeh
Neema Zadeh

Imagine two equal masses in space. I imagine their midpoint is "uncurved" in spacetime. If you move closer to one than the other, it curves one way. If you move closer to the other, it curves the other way. There _has_ to be a point (perhaps infinitely many) where it doesn't curve either way. I think the same argument applies when adding more masses... as long as spacetime isn't just all curved in the same direction (which it isn't).

Vor 4 Tage
robert J
robert J

Honestly this makes more sense then gravity always did too me.

Vor 12 Tage
Lee Nonolee
Lee Nonolee

Gravity is magnetism. Each atom that has electrons spinning around it are subject, however slightly, to the Earth, sun, etc., moving in a spiral through the universe at 515,000 mph. Each electron therefore orbits in a way similar to Earth/Moon perihelion. Sometimes closer, sometimes further away from the nucleus inducing a small differential charge, as if it were an exceptionally small magnet, very weak. But add them all up and they have immense potential. If you take a NS magnet, it will only stick thus NSNS to other magnets, however, if one were to have a thousand NS (small) magnets and scoop them up in a ball, external NS magnets would stick randomly N, then S, then N. You can literally reverse N for S and it will stick to the ball of magnets. As the atoms of everything on Earth is a weak magnet, we have gravity. So the alleged "dark matter" is nothing but electro-magnetism on both a grand and minuscule scale. We can see Birkeland currents in stellar gases pirouetting around each other in a spiral dance. Everything in the sun and stars (and each type of star) has a verifiable analog in both physical experiments with electromagnetic fields and in computer simulations.

Vor 19 Stunden
SmarterEveryDay
SmarterEveryDay

As long as I've known Derek he's consistently asked the difficult questions. This video challenged me, and taught me many things. I want to try the eclipse photo now. Impressed Eddington did it in 1919.

Vor year
Steve Jones
Steve Jones

Eclipse is about 2 years away.. Still planning on doing this?! Make a video on your planning - I know there's a lot of us who would follow along and maybe try to do the experiment at the same time. Last eclipse, we went to Kentucky to watch.. Next time we're planning on going somewhere between Texas and Illinois.. DEFINITELY can't miss it!!

Vor 3 Monate
hiren Drall
hiren Drall

I still did not understand why we dont fall on the other side of the earth

Vor 5 Monate
Juicebox
Juicebox

@Laith Ejeilat the word you're looking for is physicist, a physician is totally different from one who works on physics

Vor 8 Monate
RandomThings
RandomThings

In 1919, Whipple declared that comets were dirty snowballs. When they actualloy sent spacecraft to comets they found very little ice but lots of rock, rubble, plains, sand dunes and cliff faces. So they called them icy dirt balls. Hahahahahahahaha.

Vor 11 Monate
Wokov
Wokov

I can finally write "Love is the strongest natural force on earth" on my physics test after this video!

Vor 28 Tage
Alex Alexon
Alex Alexon

When I was 6, I saw a pigeon fly into a London tube carriage and fly over passengers' heads as the train pulled away. I laughed fit to burst, but would the pigeon have been forced to fly differently to stay in the "same" position relative to the people on the train? Trying to work it out still. 😅

Vor 17 Stunden
chichoskruch21
chichoskruch21

PBS Space Time had an amazing series about this some years ago, but it's very cool to hear it again.

Vor 6 Tage
Mitch Raemsch
Mitch Raemsch

Acceleration is the definition of the strength of gravity. Falling is acceleration by gravity field. Weightless falling is always changing speed. You can't believe gravity away... Voyagers are weightless but they are subject to gravity escape velocity slowing them down leaving. The space station doesn't have a circular orbit it is an unstable decaying ellipse. Astronomical orbits are known to be elliptical. So is that straight in space time?

Vor Tag
Mike Tacos
Mike Tacos

At this point, Newton throws his apple at Einstein.

Vor year
John Steed
John Steed

@Feynman Schwinger E_MC2 Thanks for your comments.

Vor 8 Monate
Guy The Incognito
Guy The Incognito

@Feynman Schwinger E_MC2 Thanks. You're welcome 😎👍

Vor 8 Monate
Feynman Schwinger E_MC2
Feynman Schwinger E_MC2

@Guy The Incognito This is a fantastic summary 👏👏👏. Great job. (I just hope he/she understands what you wrote, they seem to have an axe to grind).

Vor 8 Monate
Feynman Schwinger E_MC2
Feynman Schwinger E_MC2

@Guy The Incognito Fun fact, Einstein discovered most of the truly original concepts in quantum mechanics too: quantized the radiation field, specific heat of solids, wave-particle duality 13 years before De Broglie, intrinsic randomness with his trilogy of papers on Spontaneous and Stimulated Emission as codified in the Einstein A and B Coefficients, he, not Bose, discovered the Boson, he was the first to point out quantum entanglement and flesh out the reason why this was central to quantum mechanics deviation from classical mechanics even while the likes of Bohr, Heisenberg, Schrodinger etc failed to see it. I could go on and on. He's the most original scientific thinker of all time imo, and I'm not sure it's even close. In an era replete with generational geniuses, they considered him chief amongst them - which is why they insisted he sit in the very middle of the portraits they would shoot for the Solvay Conferences. The same way Einstein was inspired by Newton, Faraday and Maxwell, Heisenberg was inspired to become a physicist because of Einstein. He adored Newton, I suspect, because they were both after the same thing: they wanted to know the mind of God. Thanks for you commentary. Great stuff!

Vor 8 Monate
Martin Eizinger
Martin Eizinger

THANK YOU for critiquing the bent sheet experiment. I've always hated when people used this to demonstrate gravity.

Vor Monat
pankaj mishra
pankaj mishra

over simplification and plain wrong analogy. a similar one has been used in elementary science books to explain uncertainty principle.

Vor Monat
Vizeral
Vizeral

I'm 40 and it's incredible how I feel 14 again when I learn to see things differently like this.

Vor 14 Tage
Jake Mustian
Jake Mustian

The two situations feel different because of air resistance. You feel the acceleration of gravity because the felt wind is getting faster

Vor Monat
Pradeep Thomas
Pradeep Thomas

A year after rewatching this multiple times I should say this is really the best explanation out there on gravity. Thank you for making this video and explaining this concept. Relativity had always been beyond the reach of understanding for me, until now.

Vor Monat
bcfc ireland
bcfc ireland

@Bartley Troyan looking like he fails to understand it...if the lack of response is to go by

Vor Tag
Dan Wallen
Dan Wallen

i just watched 3 times in a row, the first i was a little befuddled, the second i thought i grasped the concept, and the third time through was to make sure i actually understood what i am now believing.

Vor 4 Tage
megapunchboy
megapunchboy

I think ser pradeep can be trusted here ser bartley

Vor 24 Tage
Bartley Troyan
Bartley Troyan

OK, explain it to me then. If you can do so, then you do really understand it.

Vor 24 Tage
Benjamin Tollison
Benjamin Tollison

Officer I can't walk in a straight line because we all walk in geodesics.

Vor year
X Zero One Armour
X Zero One Armour

You get Promoted, Private

Vor 6 Monate
Leonardo Krügel
Leonardo Krügel

And then proceds to walk in a straight line through space-time

Vor 11 Monate
sts
sts

@Brett Goldsmith Geodesics aren't straight lines to flat-earthers.

Vor year
nobody important
nobody important

In high school i always imagined the random kinetic energy in an object to be dragging it in every direction equally. Just a thousand vector lines popping off an object like the spines of a sea urchin. But if you smoosh a couple of those directions together, suddenly a lot of those directions are working together to overpower the rest. It just made more sense to me than energy from nowhere

Vor Monat
Randy Martin
Randy Martin

Mind blown, the way that you explained the formula, and explained the interaction between acceleration and spacetime, how science fiction had the idea so long ago that if superman flew around the planet in reverse, he could go back in time

Vor Monat
K F
K F

Thanks for this video! One of your more accessible ones for sure. Just one caution--your spacesuit and helmet didn't fit together to seal you in. f you go for a space walk, this could be dangerous.

Vor Monat
Owen Lu
Owen Lu

If you are in a spaceship in free fall, wouldn't the acceleration of gravity be slightly faster at the end of the spaceship that's closer to the planet? This would differ from a spaceship in an inertial frame without gravity. Could an observer in the spaceship use this to deduce the presence of gravitational force?

Vor 7 Tage
Balddakko_zara
Balddakko_zara

Veritasium: *"gravity is just an illusion"* Flat Earthers: Our Time Has Come.

Vor year
Nowhy
Nowhy

@mmldmm proof in science? Interesting...

Vor 4 Monate
mmldmm
mmldmm

if gravity is just an illusion why are they still looking for proof of the graviton?

Vor 4 Monate
Richard Singer
Richard Singer

@LewisPhillips name one of these multiple PhD holders and I will show you someone who bought multiple fake PhDs.

Vor 5 Monate
Sakis Sakissa
Sakis Sakissa

This guy is a liar "gravity does not exist" omg 🤣👏👏👏👏

Vor 6 Monate
Night Tow
Night Tow

After watching this entire video and paying very close attention, I have more questions now than I ever had before. Due credit to you though, I now have these questions because I have a better understanding.

Vor 22 Stunden
arkine11
arkine11

I could see flat-earthers enjoying this, since a flat earth would easily explain the whole not falling off on one side of the planet thing. The space-time curvature is much more complicated to wrap your head around 😂

Vor Tag
Edwin
Edwin

If gravity on Earth is the result of acceleration, which means increasing in speed every second, what speed has the Earth attained after billions of years worth of acceleration? How does General Relativity account for the results of the Cavendish Experiment? How does General Relativity account for the evenly distributed particles formed after the Big Bang being attracted together to form stars and planets?

Vor 2 Tage
Caroline Joy Barnhart
Caroline Joy Barnhart

There's one very technical issue especially regarding your charged particle. If I'm local with the particle in the same frame there's no EM radiation. But in a more global second frame there is. Also any masses interacting gravitationally will produce gravity waves. The math is far beyond what can be put in a comment, there are major in depth papers on this effect. The actual paper with this quote I've seen the most but there are others. Be warned, this is seriously heavy. ----- Radiation Damping in a Gravitational Field, Bryce S. DeWitt, Robert W. Brehme, Annals of Physics: 9, 220-259 (1960) The charged particle tries to do its best to satisfy the equivalence principle, and on a local basis, in fact, does so. In the absence of an externally applied electromagnetic field the motion of the particle deviates from geodetic motion only because of the unavoidable tail in the propagation function of the electromagnetic field, which enters into the picture nonlocally by appearing in an integral over the past history of the particles.

Vor 3 Tage
1111xyz
1111xyz

O.K. lol. Every particle in motion of all the matter within a body must have an effect. I see how complicated this is!

Vor Tag
Nolan Bie
Nolan Bie

The fact that you can make videos on topics that are so out of the ordinary, and most people would never be able understand it without years of education, into a short video that is free to watch and actually understandable is amazing

Vor year
Max Odgaard
Max Odgaard

@Sky King not even the most famous astrophysicists can explain from where gravity origins, so I am amazed you understand it. Be humble and admit you dont either :)

Vor year
Rishu Mallick
Rishu Mallick

I based on the people watching,if they are interested then they will do what they need to do to understand the video but if they are here just because they just want some of their brain cells to die then they will leave. U am just 14 i will turn 15 in july,i am studying in my last year of junior high, i was completely able to understand the whole video but i am intrested in robotics. All i have left to say now is "everything is knowledge and we should take it". Thanks for reading,have a nice day👍🏻

Vor year
Dushyant M
Dushyant M

You don't need years of education to get the basics of relativity. I read 'ABC of Relativity' by Bertrand Russell. Very beginner friendly book, very interesting and got me a good grasp of the basic concepts.

Vor year
Bruh Broham
Bruh Broham

@Max Odgaard actually, this is my mom's account B)

Vor year
Max Odgaard
Max Odgaard

@Bruh Broham stop using daddys youtube account.... and go do your homework..... yalla yalla

Vor year
עולם הגיקים
עולם הגיקים

Dude, you are amazing! I haven't watched a single video on this channel that didn't leave me completly shocked almost like Christopher Nolan does.

Vor 2 Monate
Matt Morris
Matt Morris

Man I come back to this video every couple months and I understand a little bit more and realize I don't understand a little bit more

Vor Monat
getgene
getgene

Huh. I finally get it. PS re comment below: Newton wasn't finding crazy things. Indeed he was surprisingly accurate for his paradigm, which teaches us about the logic of our ideas. They are conclusions based upon assumptions that have nothing to do with truth, if that exists. A correct answer is a valid conclusion, which is not truth, merely a logical consequence of assumptions. This is a lesson our delusional political thinkers may never learn.

Vor 3 Tage
Lew South
Lew South

Love the spacesuit with unattached helmet! And that "standard bent-sheet analogy for curved spacetime" is not just misleading; it's flat-out *wrong.*

Vor 25 Tage
Colton Smith
Colton Smith

So Newton actually rammed his head into that apple. Rude.

Vor year
Siddhant Kaskar
Siddhant Kaskar

😂😂😂😂😂😂😂😂 legends

Vor 9 Monate
James Kenyon
James Kenyon

@Memerr Thanks, somebody clued me in awhile back and so I'm good. Bottom line is professor Dave couldn't debunk his way out of a wet paper bag.

Vor 10 Monate
Memerr
Memerr

@James Kenyon lol But you don't use + to mention someone you use @

Vor 10 Monate
Artem D
Artem D

Earth is to blame here!

Vor 10 Monate
Huskie Huskerson
Huskie Huskerson

To apple? Are you insane?

Vor 10 Monate
Anish Jog
Anish Jog

1:57 The man in the rocket ship wouldn't detected Gravitational waves (assuming that there is no mass outside his spaceship perfect infinite vaccum) while the one failing of a roof would do. Could this be the experiment by which one can distinguish the two situations?

Vor Monat
Badrinath Gaming
Badrinath Gaming

Man one small doubt, If we were free falling from the top of a building, and our position is an inertial frame, does this imply that entire mass of Earth is bumping towards us? I have some following questions regarding this, and I seek no other person's help except a man with good thoughts.

Vor Stunde
CyberneticOrganism01
CyberneticOrganism01

I've been wondering about this since I first read about general relativity in high school.... for 36 years... thanks ☺️

Vor 9 Tage
Paul Gutches
Paul Gutches

If one could "fall forever" from that roof, would one suffer the same kinds of physical deterioration involving bone mass loss and red blood cell destruction seen in astronauts who experience weightlessness for extended periods?

Vor 2 Monate
Thraxus
Thraxus

@Paul Gutches Because all other factors are identical to what Astronaughts experience. Weightlessness is the only thing that Astronaughts experience regularly that regular humans on Earth do not

Vor Monat
Dave Koch
Dave Koch

Yes, because it would be absolutely no different than an astronaut experiencing weightlessness. They are literally the same thing.

Vor 2 Monate
Dave Koch
Dave Koch

@Kuhluh Ok - just trying to get it straight in my mind. As I understand it, my explanation would be in line with general relativity.

Vor 2 Monate
Kuhluh
Kuhluh

@Dave Koch well, my explanation is for the classic way of thinking about it yours is for the one of the video

Vor 2 Monate
Dave Koch
Dave Koch

@Kuhluh Is this true? Isn't orbit just an object travelling in a straight line through space time? Since the earth is bending space time that straight line is basically a circle (more of a spiral when you factor in time) around the earth?

Vor 2 Monate
*Matthew Noneya*
*Matthew Noneya*

Mom: "son did you fall down?" Son: "No mom, you fell up!"

Vor year
grindupBaker
grindupBaker

Mom: "son did you fall down?" Son: "No mom, the dratted Universe just fell up on me again !"

Vor 2 Monate
J Tyson
J Tyson

Son: "No, I went into my inertial frame"

Vor 3 Monate
save earth
save earth

@Bunsenn that's what i said in the first place

Vor 7 Monate
Bunsenn
Bunsenn

@save earth You didn’t fall down, you fell towards the center of the earth.

Vor 7 Monate
daniel howard
daniel howard

I am standing here looking down I see my feet and the ground. The ground is deff down. And happens to also be exactly where I was when I stopped falling. Unless I am upside down. I dont care what way I fell it freaking hurt

Vor 11 Monate
Jamie Hitt
Jamie Hitt

It’s like being taught that it’s a flashlight… But then finding out that it truly is a darksucker.

Vor 2 Monate
Kim Caspar
Kim Caspar

I can’t decide if this comment is insulting or funny or both.

Vor 2 Tage
Patrik6920
Patrik6920

..if you just knew how true that statement was...

Vor 13 Tage
4-D Man
4-D Man

I watched. I listened. I still don't understand. Gravity still seems like a force pulling down. So I leave the last word to Kurt Vonnegut: "All of us were stuck to the surface of a ball, incidentally. The planet was ball-shaped. No one knew why we didn't fall off, although everybody pretended to kind of understand it. The really smart people understood that one of the best ways to get rich was to own a part of the surface that people had to stick to." [BREAKFAST OF CHAMPIONS, 1973]

Vor 23 Stunden
e. p.
e. p.

WOW !! I am 47 and after watching this, for the first time in my life I comprehend the idea of space time, although being an engineer for 22 years. Thank you SO very much for this !!!!

Vor 19 Stunden
Narf Whals
Narf Whals

I have a question for an experienced engineer about how you guys use the stress tensor, if you're up for it?

Vor 15 Stunden
Shadow CSM
Shadow CSM

Derek, with the stretched sheet experiment, if there was no force being exerted on the object travelling along the geodesic line, what role does acceleration play? For instance, and I realise you said not to think of a "well", but if the object doesn't maintain sufficient countering force (via its engines), its orbit around the planet will decay and it will eventually crash into the planet (hence my simple understanding of the object sliding down the wall of the well). To break from the gravitational attraction of the planet (ie, to maintain its straightline path through space time along the geodesic), or to curve away from the planet, it has to exert a force greater than the gravitational attraction (ie, to climb the wall of the well). Or am I completely off? (This is what happens when you think year 12 physics and pure and applied mathematics is enough to answer all your questions on the nature of all things ...)

Vor 2 Monate
Seth N.
Seth N.

correct...going into those "curved sheet areas" around planets that represent space time dips and taking advantage of their ability to accelerate things is how we slingshot spacecraft in the solar system. If you skim the edge you will accelerate and yet not get caught in it

Vor 2 Monate
IMC00KIES
IMC00KIES

Props for the camera man who went through space to film this video

Vor year
IMC00KIES
IMC00KIES

@The onion from Shrek he's just a kid calm down

Vor 3 Monate
LeWoucheBait
LeWoucheBait

@JC_Boy What do you mean yeah yeah?

Vor year
JC_Boy
JC_Boy

@LeWoucheBait yeah yeah ". "

Vor year
LeWoucheBait
LeWoucheBait

@JC_Boy Yes I can, what are you talking about?

Vor year
Michelle Fitzpatrick
Michelle Fitzpatrick

I truly hope you read this comment in its entirety as I am highly curious about this and have taken a special interest in these concepts recently. I have so many query’s lately and this video although fascinating and informative has only brought up more questions. If you have any tips on books or resources I can explore and absorb I would be eternally grateful! Currently deciding if I want to go back to college for physics/theoretical likely yet I’m old and completely new to these concepts. Sorry for the novella! By your explanation of force both the positive stationary charge and the falling negative charge would give off electricity, no? The positive because it inertia matches that of the earth or possibly it’s slower which is why it stays attached to the object it’s sitting on and the negative or falling ball because it inertia is present only that it is moving at a different rate from that of the earth until it touches the ground when it’s inertia matches that of the other ball and other objects with perceived gravitational pull attached to the earths surface. What I find confusing is how our measured weight is the same regardless of where we are on the earth’s surface. I suppose this could be explained away by a higher dimension in which we can not actually perceive the true shape of the earth or it’s surroundings in outer space but I don’t have enough knowledge yet on these topics so I could just be lacking in understanding. Curious however if you have an explanation for any of this. As far as the earth expanding which honestly makes the most sense in layman’s terms wouldn’t that mean that everything else in space is also expanding at the same rate as earth? If everything in space is moving in an ever expanding manor wouldn’t this be a legitimate explanation? On another note why do we not use the ocean for more research into these concepts? Water has to bend around objects moving through it in addition at the correct depth and mass of an object, things feel weightless or their inertia matches that of the water surrounding them, right? That being said unless a round object is expanding in all directions simultaneously, another object on its surface would have different effects depending upon the part of the surface it’s touching. For example, Some things fall off the back and others are stuck. This would be the same or similar in space as under water, would it not? Water from a faucet can bend as do bullets shot in a long range, airplanes etc… interesting and yet to date none of these theories seem to truly explain well enough for us to fully understand or completely prove/disprove. Knowledge should be ever changing and expanding yet we have been so specifically focused on the already presented concepts that to date no one has expressed any valid, in-depth and provable newness. I suppose there could be some unseen variable/s no one has yet considered. If everything in our lives and perceptions has variable why wouldn’t space/time also. Isn’t time just a perception anyway. A way we as humans explain the way we experience life and history… my mind is spinning 😵‍💫 Slightly off topic but what is the possibility that the golden ratio has the ability to aid us in the understanding of some or all of these concepts? To much to explain this question but I have faith that your level of education and higher thinking can put the pieces together for this inquiry. Thank you for sharing your knowledge and helping to keep me curious and passionate about learning! I truly appreciate you and your work! Off to continue my understanding of these concepts…

Vor Monat
Michelle Fitzpatrick
Michelle Fitzpatrick

@D-man cat good point about buoyancy force! Suppose I didn’t take that into account. Like I said I’m completely new to these concepts and essentially learning from a laymen’s perspective. 🤣 still highly intrigued and apprentice of your comment.

Vor Monat
D-man cat
D-man cat

by his explination i dont think the falling one would give off anything. Im not 100% what you mean but depending on where on earth you are a scale would show slightly different numbers because the earth is not a perfect sphere nor is it uniformly dense. He explained why the earth isnt expending at 9:57 though i guess if everything is expending it wouldnt be noticable. Water also applys a force onto you called the buoyant force so its not the same as being weightless. If you ever try diving you can feel the water pushing you up.

Vor Monat
Mr Entp
Mr Entp

For your last question you can refer to the earth core , although the core is revolving on its axis but the compass you use to check the needle deflection is also on the earch and since earth core create magnetic field i think stationary charge on earth must create magnetic field.

Vor 3 Tage
1111xyz
1111xyz

Which would explain the bending of space/time around a massive object.

Vor Tag
Controlledburst
Controlledburst

I have always thought gravity didn't exist. A 'harmonic' collective synergy of the other three fundamental forces.

Vor 5 Tage
Kevin J
Kevin J

Interesting that we've been unable to test the radiation of particles. I'd be interested in seeing a video on why the particles of Earth itself couldn't be tested. Aren't they accelerating and thus radiating? And if so, any device that measures 0 for their radiation would actually be measuring their radiation with bias, thus subsequently that same device put into space would become an inertial observer, and it would then measure all other particles also in that frame of reference as a negative radiation?

Vor 2 Monate
Patrik6920
Patrik6920

@We Preach Christ ...there is no place in space where there is no movemen, no energy..infinite small yes..but not zero, the enery at such a point would have to be exactly zero kelvin...atm as faar as i know we can barely get to 0.025 kelvin atm, at absolute 0K or below 0.00000000000000000000000000000000001K ther will be Zero gravity

Vor 22 Stunden
We Preach Christ
We Preach Christ

@Patrik6920 I thought point was gravity doesn’t exist?

Vor Tag
Patrik6920
Patrik6920

its actually what is obseved....and its correct for every particle everywhere, unfourtunetly thers no plase anywher with absolute zero gravity...undetectable small yes...but not zero...

Vor 13 Tage
Aaron M. Lambert, Ph.D.
Aaron M. Lambert, Ph.D.

*As a Harvard Neuroscientist, here's another mind-bending gravity-related thought. When you rotate your head, you are NOT in control of the primary directionality of your eye movements under most circumstances.* Try this. Keep your head still and look at your finger while you shake your finger left and right; your finger will look blurry due to motion blur. Now, instead, keep your finger still and look at it while you simultaneously shake your head left and right, which will demonstrate - in this situation - that you are still able to maintain a stable image of your finger. This is because your gravitationally-influenced sense of your head in space - your vestibular system - has a hardwired reflex to move your eyes in the opposite direction of your rotational head movements. This vestibular-ocular reflex (VOR) ensures automatic dynamic stabilization of images during head movements. You are not consciously doing this, and you can not consciously override it. The VOR is truly a reflex and, interestingly, does not depend on vision. During head movements, you will still have a strong VOR if you are in the dark or if you have your eyes closed. Your VOR originates from your vestibular system, which is located in your inner ear right next to your cochlea - your organ of hearing. Your vestibular system for rotational head movements consists of a series of three fluid-filled semicircular canals that have little "hair" cells inside the canals. When your head moves up-down (pitch), left-right (yaw), or shoulder-to-shoulder (roll), fluid inside the corresponding semicircular canal flows. This head motion-induced flow bends the hair cells within the canal to ultimately send electrical impulses to your hindbrain. These electrical impulses - encoding head movement - then talk to parts of your brain controlling eye movements, which connect to your eye muscles to reflexively move your eyes in the opposite direction of your head movement. So be thankful that your sense of your head in space - your vestibular system - takes care of maintaining a stable image of the world even when your head bobs around as you walk. Otherwise, walking would be a blurry journey of craziness. Videos coming soon.

Vor year
W0LF
W0LF

WHAT HAS GRAVITY HAS TO DO WITH IT?

Vor Monat
CykeOk
CykeOk

So to sum it up... we humans have evolved a Steadicam in our heads, because if we hadn't, things would blur every time we move...? Nice.

Vor year
Dmitriy
Dmitriy

Yep, this is exactly why I hate motion blur in games. Cause usually they(devs) make it that everything is getting blurry with every move you take so even walking gives you motion sickness. And of course there is no focus on anything it just all blurs. Which normal people only experience when dead drunk.

Vor year
Throefly
Throefly

Nice. This explains handily why cameras with no image stabilization(either digital or optical) result in such shaky looking video, and by extension also why watching movies that substitute camera shake in for various special effects can be so frustrating to watch.

Vor year
nunya biz
nunya biz

Mind blown

Vor year
Vikramjit Singh
Vikramjit Singh

I always had confusion on this topic before but this video is kind of a masterpiece. Salute Veritasium ...........

Vor 2 Monate
Silentsouls
Silentsouls

The observer would not measure a straight line anymore, he himself would observe his trajectory is changing. Faster and faster the closer he comes to the object, A gyroscope should indicate this. It is so gradual a person would not feel it. but can be measured within his frame of reference. Then there is the discovery of gravitational waves. They must be something else then, but what.

Vor 5 Minuten
Ben Zöchling
Ben Zöchling

Just to test if I understood this correctly: Does that mean that Spacecrafts do a "Flyby" around a moon or planet, because that is actually the straightest line from one point to another through bend space?

Vor 2 Monate
Patrik6920
Patrik6920

@Wyatt Carhart sorry but..Yes and NO again...spacetime will bend 3D space...the craft changes direction and gain speed...even if in spacetime its a straight line, thinkof gravitational lensing...the photons is actually changing direction in 3D space...one reason it takes alot of computational power to calculate the real position of observed objects....the objects we observe is not what the position was at the time the photons was sent from those objets due t gravitational lensing...

Vor 2 Tage
Wyatt Carhart
Wyatt Carhart

I am also wondering whether or not I understood correctly, but this is a super interesting conclusion to draw and from what I understand it sounds right. The comments telling you you’re wrong sound like they’re describing acceleration in a newtonian way When something slingshots around a moon or planet like that, it causes an acceleration when you look at the 3D coordinates. However, since that “acceleration” is due to the moon or planet’s gravity, the spacecraft is still in free fall/moving in a “straight line” through spacetime. So to me it seems like that’s exactly what’s happening: it seems to go faster relative to observers, but it’s actually following the same path through curved spacetime, which means that path would technically be shorter! (If I am wrong I would love to learn; I am not a physicist) Anyways, thanks for the revelation!

Vor 7 Tage
Jeremiah Noar
Jeremiah Noar

Yes that's true. The path around the planet is the shortest straight path through space-time. Same with a ball thrown up in the air. It's crazy to think about. Vsauce did a great video on this a few years ago called "Which way is down". It's great!

Vor 13 Tage
Patrik6920
Patrik6920

YES and NO... think of it like this...the space craft is already moving trought space sitting on the ground (on earth)...its moving with the object(earth) trough space...a geodesic path is the closest path...its ofc also used for acceleration menuvers..

Vor 13 Tage
George Youtube
George Youtube

It wants to travel in a straight line but gets deviated by gravity with a change in velocity. If that was the straight line trough bent space there would be conservation of momentum, no change in velocity, just change direction. The velocity change suggests it clearly does not follow a straight path

Vor Monat
rⓞund::floor(is,lava);
rⓞund::floor(is,lava);

🤔 as this has to apply to earth's surface (and below) as well i could argue that our planet is constantly exploding while space itself is the only thing that's drawn to the center

Vor 9 Tage
Shamsun Islam
Shamsun Islam

my physics teacher: Draw an arrow showing the direction of gravity. me: [draws nothing] my physics teacher: What video did you see this time?

Vor year
Richard Moore
Richard Moore

@James Sutton You are missing the point. Locally the environments are equivalent. Any experiment you do on a sufficiently small scale will produce the same result in each inertial frame. If you expand the volume included in the experiment, then and only then will you see differences (tides and orbital mechanics are examples -- these are non-local phenomena).

Vor 7 Monate
brb
brb

@Frank Krumnow so wrong what you say

Vor 7 Monate
This Guy
This Guy

@Yori Senpai gravity 100% exists lol what do you mean

Vor 9 Monate
Nguyen Nguyen Huy
Nguyen Nguyen Huy

@James Sutton Actually, the analogy doesn't say falling and acceleration looks the same and therefore they are the same. It says that they have the same effect that is certain and stops there, thought of an experiment in acceleration and derive it into a one in gravity, which is affected by the same effect as I said, and then came up with a conclusion. This kind of comparing apples and oranges is valid. You can say that apples and oranges are all trees or dogs or whatever, and all trees and all dogs have supplies of water or have abc ... , therefore there must be a lot of water in apples, and so do oranges or some other conclusion from things in effect of abc.

Vor 10 Monate
FishermanChannel
FishermanChannel

You should draw arrow down. While gravity has no force, it still curves spacetime and arrow represents general direction of curvature in given location.

Vor 11 Monate
Science Over Feelings
Science Over Feelings

OK. I think I got it (maybe). So I have 2 questions. What happens when we are not moving from any frame of reference? And to piggyback on that, since the Universe is expanding, does that mean that nothing in the universe is motionless (no movement from any frame of reference)? That would make my first question moot.

Vor 6 Tage
Angus Uchiha
Angus Uchiha

i know this video is millions of years old. but i think about it pretty regularly. and thinking about it recently i came to a conclusion. namely: this doesn't mean Gravity isn't a force. this just means it's effects can be replicated using acceleration.

Vor Monat
Noob Gamer
Noob Gamer

I have got a question. I would be grateful if someone answers that. I know now that Spacetime is curved around the earth therefore moon which is actually moving in a straight line appears to be moving in circular orbits. But my question is even if Spacetime is curved, what causes the motion of moon in the first place? Gravity is not a force therefore why does the moon bother to move. What doesn't it just stay at one place in the curved Spacetime?

Vor 4 Tage
The0013
The0013

As the video says, staying at the same place in curved space-time requires acceleration (11:01). The moon does not accelerate (it has no engines), it just follows the same straight path since its creation. However, that straight path becomes circular in Earth's curved space-time.

Vor 2 Tage
Lee Trampleasure
Lee Trampleasure

Doesn't the model of gravity as a force still 'work' for most dynamics/kinematics/energy experiments/problems in a physics class (or even discussion)? If we define a force as an interaction between two objects, than isn't the bending of space/time simply a definition of HOW these two object interact, but it's still an interaction.

Vor 2 Monate
Korben Dallas
Korben Dallas

@Patrick Powers that actually does happen. The Earth's rotation speed is affected by many things including giant herds of animals. The migration of large groups of animals slows and speeds up the spinning of the planet. Additionally, if gravity is an illusion, then how does a black hole work? What force is pulling all that material in?

Vor Monat
Patrick Powers
Patrick Powers

The simple comment on this is that if gravity was a force then every time we dropped anything or gravity affected things then the energy used would slow down the earth's rotation on its axis and in its orbit. That we do not see. Therefore gravity is not a force.

Vor 2 Monate
fluentpiffle
fluentpiffle

The problem is that the nature of 'gravity' is linked to the nature of how existence itself operates, so there will always be a 'problem' until our understanding correlates with the actual nature of reality.. Fortunately, we live in times where this understanding is a possibility.. "Gravity is caused by the mass-energy density of space. This mass-energy density of space is determined by the square of the Wave-Amplitude and is always positive (squares are always positive). The  wave-velocity is inversely proportional to the mass-energy density of space, the higher the mass-energy density of space, the slower the Wave-Velocity. As Matter and its resultant mass-energy density of space are always positive, this causes a slowing of In-Waves as they travel through other matter/wave-motions, and it is this property of Space that causes the natural ‘Gravitational’ attraction of all bodies, and explains why Gravity is always attractive." (Geoff Haselhurst) spaceandmotion "Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon.. Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science."

Vor 2 Monate
Kuhluh
Kuhluh

well, we ALWAYS simplify stuff engineers also don't go and calculate how every single particle of a machine interact with each other (even though it would maybe be more accurate) another example: we know a few million decimal places of Pi, but even the Jet Propulsion Laboratory uses less than 50, if I remember correctly

Vor 2 Monate
Sciencerely
Sciencerely

As a stem cell researcher I've recently read about studies investigating why organisms need gravity to develop and would have great difficulties in spaceships. Early attempts of growing plants in spaceships failed since plants need gravity for their root development. However, even single cells need gravity for molecular processes. For example, the cytoskeleton (which help cells to maintain their shapes) and several protein families have been shown to be affected by the absence of gravity (it would actually be funny to make a video about that myself). Great video as always!

Vor year
BD
BD

It's mathematically proven that a large circular object to contain living quarters on a space ship can generate artificial gravity by simply spinning the object, like a spinning donut.

Vor 11 Monate
TechyBen
TechyBen

@AlbertaGeek Better semantics from me would be: The acceleration of particles and molecules in a cell use their accelerating non-rest reverence frame to push off the straight path resistance in a gravity well of curved spacetime. ;) There, no "force" in that example, but the cell is still using gravity to actually function.

Vor year
TechyBen
TechyBen

@AlbertaGeek Oh I totally understand the video. If I bounce some balls on a trampoline, these are not a "force". You can however use those balls to likewise bounce some dice off them. As you say, it's semantics. So "gravity" provides something we can push off of, in the same way acceleration provides something to push against.

Vor year
Gov Corp Watch
Gov Corp Watch

@AlbertaGeek so, you don't grasp how the conceptualization of physics is different, you just compare to the standard model and that's it. really?

Vor year
AlbertaGeek
AlbertaGeek

@Gov Corp Watch _"did you even read the energy wave website?"_ Yes, I did. That's why I said what I did.

Vor year
Corey Bray
Corey Bray

It’s kind of unclear to argue that in GR we are accelerating without a force, because merely saying we are accelerating is not a good explanation for why that acceleration has a specific directional orientation. When you are pushed by a given force, the direction the force pushes you in influences your resultant direction. When there is no force to impose direction on impact with the mass of an object, it doesn’t really tell us why an object should accelerate/fall towards or away from the earth either one.

Vor Monat
REF0202
REF0202

It feels like you could say the "force" of gravity effects space and time.

Vor 4 Tage
Riemann
Riemann

As you explained in an accelerating frame light would deflect, would light still deflect for an observer floating in space far from any gravitational effect. Would a man in space (again far from gravitational effect), still be able to see light bending or deflecting from a very very far away heavenly object like blackhole cause if he is free falling then he is in an inertial frame???

Vor Monat
MobileRDS
MobileRDS

Veritasium, thank you! I find not your presentation, but the fact being right on the spot. Also, making your presentations more accessible to public (not to mention for those not highly math addicted!), you're doing wonderful job of spreading the word of science!

Vor 2 Monate
Patrik6920
Patrik6920

I agree 204% atleast

Vor 13 Tage
Cameron Thomas
Cameron Thomas

I’ve never understood the concept of bending space time around masses until this video. And now it makes sense how light gets trapped in black holes despite having essentially no mass

Vor year
Gamer Dio
Gamer Dio

@RandomThings Interesting idea. May I ask, where's your degree? Facebook doesn't count, of course.

Vor 11 Monate
Gamer Dio
Gamer Dio

@Earl Lozano Photons do not have mass. The full equation is E² = (mc²)² + (pc)². Light has momentum, like all waves, but it doesn't have mass

Vor 11 Monate
Scott Rackley
Scott Rackley

@JWjustJW Incorrect

Vor 11 Monate
Bob
Bob

But its still defined as one of the four fundamental forces. - Could be a force that acts on space/time its so weak its very difficult to answer the question. It could be a force but acting directly on space time. This video ignores that and only looks at curved space time not what causes the curvature and how that interaction works. In the end gravity could be a force just as its currently defined.

Vor 13 Stunden
Wahab .Goldsmith
Wahab .Goldsmith

I’ve always thought of gravity like this but certain things bring to question under this model which I’d love if anyone else can help explain. If gravity is not a force, why is it that in lets say massive planets, you’d feel crushed under your own weight? Or, if you found yourself in a black hole, due to the gravitational “forces” you’d be subjected to ‘spaghettification’ due to the forces?

Vor 24 Tage
Entropie -
Entropie -

@Wahab .Goldsmith Sure, it didn't want to mix the two topics for clarity. Essentially in GRT a planet with more mass would bend spacetime more than a planet with less mass. This leads to more curvature of spacetime which leads to geodesics that want to move you more to the center of mass. Now since the planet is in the way of that movement it will have to apply a bigger force to keep you from following your geodesic. It is vitally important for understanding GRT to always remember that spacetime includes time and that that has some consequences: An object traveling a straight line in spacetime corresponds to an object traveling in a straight line in space WITH a given constant speed. So the geometry of space time not only naturally affects the path you take in space but also the speed with which you are travelling along said path.

Vor 15 Tage
Wahab .Goldsmith
Wahab .Goldsmith

@Entropie - Hey! Thank you for your brilliant response. I’ve had a brief skim over it and I’ll be breaking it down more thoroughly as well. I noticed you didn’t explain the second part of my question, unless I possibly missed it. Can you clarify why “gravitational forces” on different masses of planets will exert different “forces” onto your body if said forces do not exist?

Vor 15 Tage
Entropie -
Entropie -

​@Wahab .Goldsmith spaghettification is an effect due to tidal forces of gravity, as such understanding how the tide due to the moon works on earth already gets you to also understand why falling into the singularity of a black hole will turn you into spaghetti. The benefit of thinking about tides rather than black holes is that the behavior of tides can be explained by Newtonian Physics whereas a black hole can not exist in the frame work of Newtonian Physics. Here would be the Newtonian explanation: Tidal forces are a consequence of gravitational force between two objects declining by the square of the distance. So the water on the side of earth facing the moon will experience more gravity than the center of mass of the earth, leading to a net force bulging it out. The water on the opposite side will experience less gravity than the center of mass, leading to a bulge on the opposite side. When talking GRT gravitational tidal forces are closely linked with the curvature of space time. Technically you could differentiate between a free fall towards a planet and just drifting in outer space by looking at the tidal forces you are experiencing thus measuring the curvature of space time. This does require however, that you are not reducing your observer to a single point. When falling into the singularity of a black hole (notably this is different from falling into the event horizon, which you may as well be able to do unscathed depending on the size oof the hole) the difference of acceleration as a measure of distance from the singularity will become infinitely big so you will do what the ocean on earth does towards the moon, just infinitely much, turning you into spaghetti.

Vor 15 Tage
Wahab .Goldsmith
Wahab .Goldsmith

@BigBadT Likewise!

Vor 21 Tag
BigBadT
BigBadT

@Wahab .Goldsmith as a science geek myself, i must agree. Some things are beyond imagination and are minds are too simple to comprehend them, some experiments are still impossible with current technology. But that's the beautiful part about science, there will always be room for exploration. Things must be disproved/ proved regardless of sentiment, for the truth must be uncovered. Nice talking to you

Vor 21 Tag
bmbdr529
bmbdr529

I'm still having trouble understanding how spaceships' slingshot maneuvers work when they pass close to planets. There should be no noticeable acceleration for the space traveler. Are they just taking a shortcut through space-time? Why are they faster after leaving the planet relative to the earth afterwards or are they not at all?

Vor 2 Monate
Ulaş Aldağ
Ulaş Aldağ

The maneuver of a ship around a planet only changes the trajectory of the velocity relative to the planet, without changing the actual value. Relative to the planet it slingshots around, it has still the same velocity just in another direction, so it actually doesn't accelerate. The magic happens when you look at it relative to the sun after the maneuver. The changed component of the velocity is now partly parallel to the velocity around the sun and therefore increaes the total velocity relative to the sun. Of course this scenario only works for acceleration, you could also use it for a braking maneuver by turning the velocity in the opposite direction.

Vor Monat
John Walsom
John Walsom

Exactly! I can never understand why you don't lose on the way out what you gained on the way in. Maybe it is just being used for the change of direction ie no net gain in velocity, just staying on the right track.

Vor 2 Monate
TacticusPrime
TacticusPrime

The planets are also moving relative to the sun and to the Earth. The spacecraft gets close behind the planets, using the traveling warp of spacetime as a sort of tug to increase their own speed relative to the sun and the Earth. Like Marty McFly on his skateboard behind a truck.

Vor 2 Monate
Ryan Lloyd
Ryan Lloyd

Thank you so much for clarifying the ball on the sheet model of gravity that has been baffling me for a long, long time...

Vor 4 Tage
Neel Bagayatkar
Neel Bagayatkar

Imagine having a physics class where you learn gravitation fields and forces then go on to watch this video right after...

Vor year
Syn
Syn

@Kilo Mintoni stop talking and get a life

Vor year
Gene K
Gene K

@Dagm Bisrat, Please don't; teacher's don't make enough to deal with this.. Newtonian model explains what happens on Earth just fine and it is way easier to understand. That's why it is still taught in school. And Einstein model is not complete - it will also be proven "wrong" in some future :)

Vor year
Rogue CHlNCHlLLA
Rogue CHlNCHlLLA

@Ryan Rich Have you never taken a high school physics class?

Vor year
Diogo Manteu
Diogo Manteu

@Priyanshu Kumar because its not compatible with quantum physics, its incomplete, but it hasnt failed at what it wants to do and does far better than Newtonian physics at larger scales

Vor year
Elias
Elias

Oof that would hurt

Vor year
ToastyMemes
ToastyMemes

My brain just did a backflip into a pool of lava.

Vor Monat
Adrian Gheorghe
Adrian Gheorghe

Devierea luminii in campul gravific al astrilor, nu s-a observat si la radiatiile ics si gama. Radiatii care avand energie mult mai mare, ar trebui sa fie deviate mai puternic. The deflection of light in the gravitational field of the stars has not been seen to occur on ics and gamma radiation. Radiation that has much higher energy should be deflected more strongly.

Vor 21 Tag
account old
account old

Oh yeah, the Sagnac effect - used specifically on ring laser gyroscopes. Acceleration of the gyroscope induces a small phase shift on the laser, which is detected by an interferometer.

Vor 2 Monate
SupremeOwnage
SupremeOwnage

The real mystery is time dilation. Why do we all continue to percieve the passage of time as constant, whereas from a different reference frame we're moving slower? I've often wondered if all the galaxys of the universe are running at different speeds because of all of the differences between their velocities....

Vor 4 Tage
Arturo Eugster
Arturo Eugster

That is the subject of special relativity and the Lorentz transformation .

Vor 3 Tage
TheFantasticFreak
TheFantasticFreak

You would certainly see the difference if you were travelling very fast while having a video call with your friend

Vor 4 Tage
Diego Solis
Diego Solis

What I find the most amazing about Newtonian physics, is that Newton was able to come up with so many simplifications for phenomena that are incredibly complex and plainly "crazy". That man made science possible for so many minds which then lead us into a world in which we have a deeper understanding of the universe and still his simplifications work beautifully in most cases. He came with approximations that measure the effect of the complexity, rather than the complexity itself. Ain't physics and math a couple of beautiful things? Sure they are!

Vor 2 Monate
Henry Knight
Henry Knight

Without Newton's three laws and infinitesimal calculus is hard to imagine The First Industrial Revolution ever taking place.

Vor 4 Tage
james deroc
james deroc

there can still be discoveries in the future that change or make invalid the scientific assumptions we hold as basic and immutable. he was wrong then and so are we just less so. the history of mankind is the history of misapprehension. we will never achieve perfect understanding of the universe. its amazing the understanding we have achieved given this faculty for abstract conception evolved for the purpose of finding food and getting laid. . . . boy did we run with it.

Vor 5 Tage
Sriharsha C V
Sriharsha C V

He didn't think in terms of curved space time. He simply noted that point masses follow inverse square law and created a neat model of gravity which people so far failed to do. It is not that he understood it and then dumbed it down for the masses.

Vor 6 Tage
craig craig
craig craig

@Diego Solis the apple thing was made by voltaire i beleive

Vor 6 Tage
Diego Solis
Diego Solis

@cmalc8 Right!? For practical uses, they are as precise as needed. Our whole modern world was built under these approximations and we now are learning how more complex the universe actually is, and how crazy some rules we thought simple are in truth. It's amazing. That's what science is for! The thrill of discovery!

Vor 13 Tage
bifimi
bifimi

If it is really a relevant aspect, what a person feels and that the person feels inertia, then this theory is disproved. The person falling from the roof feels not only inertia but also the same kind of butterflies in the stomach like in an extremely fast accelerating car. So completely different than the experience of the astronaut.

Vor 17 Stunden
dwtttttttttt
dwtttttttttt

Accelerating in a spaceship, might be distinguishable from a gravitational field, as two things falling besides each other on the earth should not move in parallel but come slightly together, the further down they fall.

Vor 5 Tage
Ryali Sai Anudeep
Ryali Sai Anudeep

"Matter tells space-time how to curve Space-time tells matter how to move" I don't know about others but that sounded so cool!

Vor 20 Tage
Swizard101 Genius
Swizard101 Genius

That claim, straight path through curved space time needs to be explained as to how a ball thrown straight up will eventually fall straight down. What made space time curve like a hair pin at the top of the ball's ascent?

Vor 2 Monate
Kaappo Raivio
Kaappo Raivio

This stuff is very hard to present well. However, you presented it in a way that me, a high school student, could understand it. You, sir, are a living legend.

Vor year
saad aijaz
saad aijaz

ahhh trust me as a undergraduate studying physics general relativity ia quite fuckin hardXD

Vor year
slicedpage
slicedpage

sometimes the most complex conundrums are really just common sense. Thank you

Vor 2 Monate
Michał Opiński
Michał Opiński

It all comes down really to how we "exist" on the surface of planet earth. Similar as with standing in a bus as it accelerates and slows down, if you don't hold on or resist with your legs to stand still, you will "stay in place" so to speak, while the whole bus just goes off. When you stand on the ground, the acceleration works constantly on your legs, so if your legs give in (due to exercion, sickness or whatever), you fall down. We learn from the young years how to fight this acceleration, how to learn to steady ourselves while the acceleration keeps pushing us against the ground. Truly fascinating.

Vor 7 Tage
Nebula_Wolf
Nebula_Wolf

so do electric fields exert a force? or are they defined differently to gravitational acceleration? would a charged particle being accelerated by another be in an inertial reference frame?

Vor 4 Tage

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