Why No One Has Measured The Speed Of Light

  • Am Vor 8 Monate

    VeritasiumVeritasium

    Physics students learn the speed of light, c, is the same for all inertial observers but no one has ever actually measured it in one direction. Thanks to Kiwico for sponsoring this video. For 50% off your first month of any crate, go to kiwico.com/veritasium50

    Huge thanks to Destin from Smarter Every Day for always being open and willing to engage in new ideas. If you haven't subscribed already, what are you waiting for: ve42.co/SED

    For an overview of the one-way speed of light check out the wiki page: ve42.co/wiki1way

    The script was written in consultation with subject matter experts:
    Prof. Geraint Lewis, University of Sydney ve42.co/gfl
    Prof. Emeritus Allen Janis, University of Pittsburgh
    Prof. Clifford M. Will, University of Florida ve42.co/cmw
    The stuff that's correct is theirs. Any errors are mine.

    References:
    Einstein, A. (1905). On the electrodynamics of moving bodies. Annalen der physik, 17(10), 891-921.
    (English) ve42.co/E1905 (German) ve42.co/G1905

    Greaves, E. D., Rodríguez, A. M., \u0026 Ruiz-Camacho, J. (2009). A one-way speed of light experiment. American Journal of Physics, 77(10), 894-896. ve42.co/Greaves09

    Response to Greaves et al. paper - arxiv.org/abs/0911.3616
    Finkelstein, J. (2009). One-way speed of light?. arXiv, arXiv-0911.

    The Philosophy of Space and Time - Reichenbach, H. (2012). Courier Corporation.

    Anderson, R., Vetharaniam, I., \u0026 Stedman, G. E. (1998). Conventionality of synchronisation, gauge dependence and test theories of relativity. Physics reports, 295(3-4), 93-180. ve42.co/Anderson98

    A review article about simultaneity - Janis, Allen, "Conventionality of Simultaneity", The Stanford Encyclopedia of Philosophy (Fall 2018 Edition), Edward N. Zalta (ed.) ve42.co/janis

    Will, C. M. (1992). Clock synchronization and isotropy of the one-way speed of light. Physical Review D, 45(2), 403. ve42.co/Will92

    Zhang, Y. Z. (1995). Test theories of special relativity. General Relativity and Gravitation, 27(5), 475-493. ve42.co/Zhang95

    Mansouri, R., \u0026 Sexl, R. U. (1977). A test theory of special relativity: I. Simultaneity and clock synchronization. General relativity and Gravitation, 8(7), 497-513. ve42.co/Sexl

    Research and writing by Derek Muller and Petr Lebedev
    Animations by Ivàn Tello
    VFX, music, and space animations by Jonny Hyman
    Filmed by Raquel Nuno

    Special thanks for reviewing earlier drafts of this video to:
    Dominic Walliman, Domain of Science: ve42.co/DoS
    Henry Reich, Minutephysics: ve42.co/MP
    My Patreon supporters

    Additional music from epidemicsound.com "Observations 2"

Gaming!
Gaming!

This doesn’t make sense it is impossible for something to go faster than the expansion of the universe.

Vor 7 Minuten
Artur Paiva
Artur Paiva

I'm not a physicist, I don't actually know what I'm doing but i want to understand why this idea I had would be wrong: You put a clock and sync them with a wire which sync with a signal that travels at the speed of light, right? Now we have a round trip speed of light right? So when we measure the speed of light we actually need to dive by two assuming that the way forward is the same as the backwards. What if we use that value to define the speed of light on the timer? If we sync the time taking into account our current understanding of the speed of light and the speed of light is equal both forward and backward on the round trip when we try to measure the time using the displacement that we think is the speed of light both clocks at the end, considering the speed of light should sync exactly. Like B - c = A. Assuming A is the timer on the first clock, B is the timer on the second clock and c is the current understanding of the speed of light. If that expression evaluates true, it would mean that the speed of light is actually equal? And if it's not we would know the ratio between the round trip of the speed of light. It's not much like discovering the one way speed of light as much as checking if the speed of light is what we think it is based on Einstein convention. And if not, by how much is different, and using the difference to discover the actual speed of light. Again, not a physicist, just a curious person.

Vor 25 Minuten
Jacob Koehler
Jacob Koehler

I figured it out. A long af POLE!! Have a pole reaching from the end point BACK to the start point. Have a laser measure when the pole moves. Make the pole move and start the clock at the end AND the laser shot from the beginning at that exact moment. EASY.

Vor 57 Minuten
Corex
Corex

Wouldn't it be quiet "simple" to measure that? For my measurement you'd need two people in 2 different places in space. Prior to the experiment we give every person one particle of a set of 2 entangled particles. According to physics entangled particles share their information immediately (not just speed of light fast but IMMEDIATELY). Person A now sends a light signal to Person B. If we now measure the difference between the light arriving Person B and the time the entangled particle of Person B got his "update", then we can measure the speed of light. (Do that process for all 6 directions and we can be sure of the speed of light and if it changes depending on the direction.) I may have oversimplified a bit too much. If so, it'd be really appreciated if you could explain the mistake(s) I made in this approach.

Vor Stunde
Counsel & Might - Dr. George Antonios
Counsel & Might - Dr. George Antonios

Help me out someone. What about the reverse scenario: Could the speed of light be instantaneous on the out-going trip and c/2 on the return trip? Isn't that the scenario implied when he says we might be seeing the stars as they are now?

Vor Stunde
mike craven
mike craven

Why is it always coming from earth first. If Mars was instant, if Mars sends their time and it's instant, then they would be able to know the difference in clocks.

Vor Stunde
Muz Lee
Muz Lee

And how do you know what time is at mars?

Vor Stunde
Mister Whalrus
Mister Whalrus

this seems that the speed of light is similar to the speed of sound. sound travels differently in other particles. Maybe it is similar to that?

Vor 2 Stunden
Muz Lee
Muz Lee

We know that the speed of light if different in different substances. The question here is the direction.

Vor Stunde
UK Mike
UK Mike

The slow mo guys recorded the speed of light on film as shown on their channel 2 yrs ago

Vor 2 Stunden
Muz Lee
Muz Lee

He talked about it in the video and explained why it doesn't mean anything.

Vor Stunde
Anders Sorenson
Anders Sorenson

how does this not be affected by massive objects warping spacetime?

Vor 2 Stunden
Robert Dr. Frank
Robert Dr. Frank

How about bending the light around a black hole? From the Photons perspective it went in a straight line without changing directions at all. So if the round trip takes the right amount of time for c to be the right speed we can assume that direction doesn‘t matter.

Vor 2 Stunden
Muz Lee
Muz Lee

How do you create and controll a black hole?

Vor Stunde
StandBone
StandBone

If speed of light was c/2 in one direction and infinite in the other, then, as already pointed out in the video, we would look into the past in one direction and look at the present in the other direction. But the universe looks the same in all directions, there is no "special" direction. So we can say this question isn't just a case for Occam's razor. The differences of c in different directions is statistically insignificant (compared to the size and age of the universe).

Vor 4 Stunden
Ashu
Ashu

Damn.

Vor 4 Stunden
Daft Studios
Daft Studios

Not sure if this is possible, but if we hypothesise the one way speed of light to be 299 792 458 m/s surely there's ways to measure the accuracy of this. 1) we can predict where the photon will be 0.001s about 300km away in a vacuum, so you set up the experiment as normal, but with the mirror 300km away in space, probably in space. Then on the return to the sensor, about 150km away from the mirror an object would be timed to perfectly block the light after 0.0014s or so. So if the light reached the clocks sensor again before the object blocked it, we could determine it traveled faster than expected on the return than the initial journey! I think. I had another way I was gonna type out but honestly I'm tired and gonna get back to my pizza 🥱✌🏾 thank me later physics, with food or summin 🍕

Vor 5 Stunden
caleb wiggins
caleb wiggins

OK so here's a better one for you, what is the speed of dark?

Vor 6 Stunden
yanksrule4me
yanksrule4me

Is it possible/has it been done to attempt using 2 mirrors reflecting the light in the shape of an equilateral triangle to see what the speed of light x3 would be. Then determine if it matches the round trip numbers? I’d love to know the answer to this. My first assumption is the act of refracting light to change direction might slow it down but it might also be possible to take that into consideration when done.

Vor 6 Stunden
Luc squame
Luc squame

ah. did you really think that time exist?

Vor 6 Stunden
Ryszard Muchowiecki
Ryszard Muchowiecki

The same says Szostek PL in his work.

Vor 6 Stunden
KChannel
KChannel

What if we shine a laser at a mirror and then we put a clock at the end point of the laser and then we send a signal to the starting point but use a long stick to send a signal to the clock on the starting point, and because we know the speed of sound, we could subtract the delay, and measure the one way backwards speed of light? Also, what if we put an observer in the middle of mars and earth and we send a signal 10 minutes later to the observer after sending it to the clock on mars, if the speed of light is unequal in different directions, the observer received the two signals at the same time, if it was the same, the observer would receive the first signal 10 minutes earlyer Also, if my second thought is not right, i don't think it would matter at all if the speed of light is the same or unequal of the round trip or the one way trip, as we or anything in the universe wouldn't be able to observe it/react to it or anything really

Vor 7 Stunden
Norbert Grzeda
Norbert Grzeda

Doesn't CMBR disprove possibility of different speeds of light? Could it look so homogeneous if that speed wasn't constant in every direction?

Vor 7 Stunden
why do i have 31 subs
why do i have 31 subs

why move the clocks kilometers away? Just make them close to each other and shine a laser into it. And we can just math our time to one mile right? Basically just add up our time we got from the test until we reach one mile. No time dilation or anything

Vor 8 Stunden
TopGoose
TopGoose

You will be measure the 2 way measure of C as the laser would run at the Speed of light how would know if light is instant 1 way.

Vor 7 Stunden
Pritty Anonymous
Pritty Anonymous

Ok so i think to measure the speed of light with two clocks you Need to start the 2 clocks at the same time than move Both clock 500 meter different ways than when the first clock with the laser shoots it stoppes the first clock and when the light reaches the 2e clock stoppes so that and then you simply subtract the time. in this way the time dilation is the same so the time dilation is not a problem anymore

Vor 10 Stunden
TopGoose
TopGoose

This still has the issue as time changes correlated with the speed of light you will still have the same problem with a 2 way speed of light.

Vor 7 Stunden
Jerrome Lappin
Jerrome Lappin

The capricious ring pivotally skip because daisy meteorologically allow mid a nervous doctor. obnoxious, alert path

Vor 10 Stunden
Larkangsa Boro
Larkangsa Boro

Bangke jadi kepikiran, hahaha Selama ini gw terima aja,

Vor 10 Stunden
Sars2 Pen
Sars2 Pen

This arguments are FOOLISHNESS... Todays light speed is almost perfect at maybe error of 1part per trillion. . .if today's light speed calc is very much erroneous... Computers and quantum computing is pinis . . .butt due to the fact that much computers are very less erroneous todays proves correct on our current understanding.

Vor 14 Stunden
Aaron Cooke
Aaron Cooke

I have a theory on how to measure the speed of light one way. You have a laser, a vacuum and two clocks. You put the two clocks in the centre of a kilometre and synchronise them, you move both clocks to the start and end of the kilometre at the same speed so they have the exact same delay and then shoot the laser from the first clock to the second and then subtract the time from the second clock with the time from the first.

Vor 14 Stunden
Muz Lee
Muz Lee

@Aaron Cooke At the end of the day they would travel the same distance in a single direction.

Vor 57 Minuten
Aaron Cooke
Aaron Cooke

@Muz Lee maybe u could spiral the two clocks outwards so they they are travelling in all directions?

Vor Stunde
Muz Lee
Muz Lee

@Aaron Cooke Time dilation is based on the speed of light, if it's not equal in all dierction then the dilation wouldn't be either.

Vor Stunde
Aaron Cooke
Aaron Cooke

@Muz Lee he’s moving one clock I’m saying if u move both of them then they will be the same

Vor Stunde
Muz Lee
Muz Lee

You really did just ignore liek 70% of the video? You can't move the clocks. And you can't sync them if they are far away.

Vor Stunde
vleesevlons
vleesevlons

Why don't we just measure it with light lol

Vor 18 Stunden
NC TTS
NC TTS

what if you just put a third time measurement in between the light and the mirror. if all four measurements are equal its consistent

Vor 19 Stunden
Yash Shah
Yash Shah

Thought: Just like this, can we not think that the nobody has measured an instantaneous velocity of light or even anything at this point? From the Riemann sum (I think) we assume every quantity in their instantaneous form, and thus this.

Vor 19 Stunden
Anon Surfer
Anon Surfer

Cop: Do you know how fast you were going? Werner Heisenberg: No, but I know where I am.

Vor 20 Stunden
Anon Surfer
Anon Surfer

So, the one way speed of light being different has no implications whatsoever on the age of the universe?

Vor 20 Stunden
William Howard
William Howard

I have a question for you actually, if the experiment of measuring the speed of light is done multiple times in multiple directions or ways (sorry for the limited physics jargon) and still produces the same result, not yielding different values for the speed of light over its 2 way trip, wouldn’t that be sufficient to conclude that it is in fact a constant speed? Because if the speed of light changes based on its direction, I believe you would find that that it wouldn’t always average out to C, but in fact should yield a variety of numbers around there. the assumption in the proposed question of the video is that if the speed is slow one way that it must be equally faster the other and thus equals C when divided by 2 (I believe). So my question being this, if the speed of light is not a proven constant, are there experiments that prove it could travel fast both ways, or travel slow both ways? If not I believe that would conclude it travels at a constant rate both ways (in a vacuum of course) I would love a reply and any help in understanding if I’m missing something. Much love.-will

Vor 20 Stunden
Anon Surfer
Anon Surfer

Isn't all the matter balanced out by equal amounts of anti-matter? It's just that we (ordinary matter) are not interacting with that anti-matter and so there must be another force preventing such an interaction.

Vor 20 Stunden
Cole Child-phillips
Cole Child-phillips

Could you build a mirror circle with a receiver on one end and a transmitter on the other side. I was also wondering I don’t really know anything about physics but is it possibility that if you have a constant light source such as the sun is it easier for photon to pass the same route they came from? I guess what I’m asking does energy create a path through space and time and is it easier to travel along predetermined photon path or new ones I don’t know if that even make sense LOL

Vor 23 Stunden
Paulius Vaitekūnas
Paulius Vaitekūnas

If we have one mirror and say light travels 2 sec back and forward, then use second mirror placed at shape of triangle, if light gonna come back in 3 sec, speed is the same, i light travels we say one way in 0.5s and 1.5 back using one mirror, with two mirrors you will get 0.5+(2x1.5)=3.5sec or 1.5+(2x0.5)=2.5 sec depends on speed changing.

Vor Tag
Nobody Cares
Nobody Cares

have the clocks sync with fiber optics and then just do some ping test and get an average ping time

Vor Tag
Elijah Martinez
Elijah Martinez

Interestingly I believe the initial experiment mentioned in the video by Fizeau could be modified to measure the one way speed of light, or at the very least give a very good idea of whether directionality matters as mentioned in the video. You have already bounded measures of the speed of light already from experiment and physical laws. As mentioned even if directionality matters it can vary only between c/2 and infinity, and these extremes would be very easy to determine as below: Experimental setup: If you had a source of light (like a laser) pointed towards a light sensor over a great distance, and then in front of the sensor you placed a very large but gapped rotating non-reflective object of known thickness (in the original experiment it was a cog but here it might be a cylinder with a tunnel), you could rotate the item up to speeds to determine at what point the light sensor no longer was receiving any light signal. The light beam would need to travel across the distance of the tunnel before the object rotated enough to block the light beam from exiting. Even if this causes some experimental error with modern instrumentality it would be reasonably precise (the original 1800s experiment came within 5%), enough to determine when repeated in multiple directions if there were any measurable difference.

Vor Tag
LaserGD
LaserGD

When the two clocks are syncronyzed toghether and then because of the relativity they get unsyncronyzed, is there anyway for us to know the time delay on the moving object and then substract It right when its the whole kilometer away?

Vor Tag
Antwon Tidwell
Antwon Tidwell

I'm not scientist but what if we can't measure the one way speed of light because light doesn't just travel one way 🤷🏾‍♂️

Vor Tag
Keith Wood
Keith Wood

I just saw an invention where someone created a film camera that can record at over a trillion frames per second. Wouldn't that be able to deduce the actual speed of light? Actually you can lookup -- "FILMING THE SPEED OF LIGHT AT OVER 10 TRILLION FRAMES PER SECOND". --On YouTube

Vor Tag
Muz Lee
Muz Lee

Or you can watch this video again. He explained why that doesn't help.

Vor Stunde
Keith Wood
Keith Wood

Lookup "Filming the speed of light at over 10 trillion frames per second"' on YouTube.

Vor Tag
Aaron Austin
Aaron Austin

If the speed of light is instant in one direction wouldn't that mess with redshift and the way the universe looks in different directions?

Vor Tag
STABZ
STABZ

So if the speed of light has never been accurately measured, and a light year is the distance light travels in a year, then we have actually never measured the distance or size of anything in our universe, and all that shiz is just conjecture? 🤔

Vor Tag
Big Meaty Rod
Big Meaty Rod

I believe you did a video on synchronization what if both the clocks a kilometer apart were attached to the same hanging object and we let them synchronize naturally. could you not then find the speed of light in one direction with connectively synchronized clocks

Vor Tag
Big Meaty Rod
Big Meaty Rod

also for your example at 9:52 could you not send a pulse to start the clocks and then send a pulse to stop them (instead of the laser starting and stopping) and then compare the times and observe the difference, you wouldn't be observing a 2 way trip because they are 2 separate trips in the same direction (edit: to clarify this would be an expariment to see if there is a different speed of light in different directions)

Vor Tag
Christopher Heath
Christopher Heath

Could you entangle two atomic clocks to measure the one-way speed of light?

Vor Tag
Matthew Schneider
Matthew Schneider

Hmmm. This is really fascinating. Could you build an entire sphere of cameras to measure the light passing through a bottle and compare them for discrepancies in time of the OPPOSITE camera. Wouldn't that inform you if it is somehow directional based? It wouldn't tell you if you the act of impact before returning the light to the camera has some kind of transitive property, but it does seem to answer one of the big questions this video poses? Please, poke holes in this thought.

Vor Tag
Edson Vinícius Santos Vaz Ronque
Edson Vinícius Santos Vaz Ronque

well, if we mesure with a single central clock in various directions at same time? if there is a difference, it should be presented, different times will be mesure.

Vor Tag
Epic Man
Epic Man

Send a message containing the exact time to point B then, send a message back to A with the exact time received

Vor Tag
James Timmons
James Timmons

As neither physicist nor mathematician, I would assume this problem is better approached like most mathematical proofs: assuming the speed of light is different in two directions and showing that this leads to a contradiction. The assumption that the speed of light is infinite in one direction seems clearly wrong (again as non-physicist), since looking in one direction you would instantaneously see the big bang occurring. But if the difference is small, it could possibly explain the cases where symmetry is broken. To investigate this, I think you would need to calculate expected asymmetries in something like the cosmic background radiation and see which assumption best fits the data. It also seems (again as a non-physicist) that different speeds in different directions requires a field effect and a field effect requires a new particle, just as gravity requires the Higgs particle and field. Unless you can identify such a particle, it would seem unreasonable to assume different speeds in different directions. Thoughts? Am I completely off base here?

Vor Tag
Strahil Valkov
Strahil Valkov

why don`t you use Quantum teleportation to sync the clocks

Vor Tag
Redstone Engineering
Redstone Engineering

@16:30 is an illusion cast as if a frame of reference exists in which absolute simultaneity can be determined? Is what precedes predicated on this assumption? In chapter 9 of Einstein's paper (relativity) he clearly states "Every reference-body (co-ordinate system) has its own particular time; unless we are told the reference-body to which the statement of time refers, there is no meaning in a statement of the time of an event." I enjoy the excellent visualizations in the video illustrating what we know about how the laws of physics play out, but several convey the notion as though a frame of reference exists from which the time dilation of clocks can be observed that will be invariant to all observers, regardless of their frame of reference. And from the perspective of that (mythical) frame of reference, it can be posited that anisotropy in the directional speed of light cannot be ruled out. I thought Einstein clearly demonstrated the incorrectness of the notion of absolute simultaneity. Unless I misunderstand, it is this that undermines the methods portrayed in the video. Others have interestingly raised the possibility of employing quantum entanglement for a different approach. That might be a more viable approach here on the surface of earth, but here's one for theoretical consideration. If we could observe the surface of the event horizon around a black hole, if that surface is concentric with the location of the singularity, would that not all but eradicate any supposed anisotropy in the directional speed of light? Issues related to a lack of absolute simultaneity would not be relevant. In case it isn't obvious, the curvature of space-time around the black hole, and the path of moving masses in it, unambiguously reveals the location of the singularity. But an anisotropy in the speed of light would cause the event horizon to not be concentric about the singularity. So, I would posit that it is theoretically possible to definitively answer whether the speed of light is invariant with respect to direction (isotropic, not anisotropic) or not. In fact, in light (no pun intended) of the work of the EHT team (first pictures of black holes), with the images and data they have right now on the black hole in Sagittarius A*, they could probably calculate values (with error bars) on anisotropy with respect to the directional speed of light. At least in the neighborhood of Sagittarius A*. ;-) That is real science that could be done right now (if somebody isn't working on it already). And, that result would be an effective measurement of the one way speed of light.

Vor Tag
Ruslan Yakushev
Ruslan Yakushev

Why not sent a few messages from one planet to the other which themselves would contain times. Doesn't matter if the time is synced. Based on that you cloud calculate a delay on both sides

Vor Tag
Lavinia Sousa Rodrigues
Lavinia Sousa Rodrigues

What about a quantum clock?

Vor Tag
Pratham Jain
Pratham Jain

' KiwiCo at the end of the show ' Rhyming words.

Vor Tag
Jasraj Singh
Jasraj Singh

"As long as the round trip works out to be c, none of physics breaks" I don't understand how that's true. Why would laws concerning one way travel not be affected?

Vor Tag
Dillon Walker
Dillon Walker

This is just an illusion caused by the intuition that synchronicity is fundamental, rather than relative, no? I mean, relativity tells us that whether two events happen at the same time or different times can vary depending on your reference frame, which is very freaky and counterintuitive to our human brains. So all this "one-way" speed of light stuff is just taking advantage of that fact, and pointing out that there are also differing *mathematical* reference frames (if you will), which also give an adequate, self-consistent accounting of the passage of time in the universe.

Vor Tag
Garrett Melton
Garrett Melton

If I have a board 1 light year in length and I push on side does the other side move instantly or 1 light year? Lol

Vor Tag
Gert Jan Van der Gugten
Gert Jan Van der Gugten

Vsauce has a video on this if I'm not mistaken

Vor 51 Minute
james14294
james14294

Could you use quantum entanglement for clock synchronization? In fact, how does relativity affect quantum entanglement?

Vor Tag
Guilherme Bustos
Guilherme Bustos

IF The speed of light is faster than almost every tihng how can the dark get there first

Vor Tag
psedog
psedog

I was expecting you to talk about the loss of speed when it reflects and had to change direction. Also, how gravity plays a role.

Vor Tag
lazy lasagna
lazy lasagna

gravity only affects time dilation and for the experiments proposed it wouldn't change anything with the results or at least not in a way that we couldn't account for

Vor 3 Stunden
kerry mackey
kerry mackey

The aboard element possibly appreciate because harbor emphatically receive anenst a versed pocket. military, actually jogging

Vor Tag
Brian Hughes
Brian Hughes

There are two thoughts that occur to me.... both unachievable as far as I know, but one perhaps slightly less so! 1) Utterly theoretical - find a path of space time so curved as to return the light back to the point of origin - one way trip, but probably need to be so close to the edge of a black hole neither the observer or measuring instruments would survive to relay the data. You would also have to know it was a vacuum as any medium would alter the speed and have other effects. 2) if measuring speed of light between, say, a station on the Moon and one above the atmosphere on Earth - both Earth and Moon stations would need to find a distant object to reference against that gave off unique and specific emanations that were observable from both stations, with a pattern that made it possible to synchronise both stations with a degree of certainty. The distance of the other object would have to be far enough so that it would minimise any uncertainty in the patterns observed by both stations. It would also never be exact, but it might provide a more accurate approximation.....? I'm sure there are effects I haven't taken into account so please feel free to point them out! :)

Vor Tag
John DeF
John DeF

Why would light suddenly slow? This reminds me of the casually disconnected parts of the universe. If they came from same origin why wouldn't they be the same?

Vor Tag
Zeno Lord
Zeno Lord

Ok here is 2 ideas I had, 1 what if you had that satelite that would sent the time, now lets say one person is 100km west, and the other 100km east and they are both in the same time zone, both people have a internet synced time on their device, then they both receive the time saying 12:00:00, the person in the east could say, oh its 12:00:00 aswell so it got here instantly, then the person in the west said oh it's 12:01:00 so it took 1 minute to get here. In that scenario isn't it measured in a one way direction? Okay scenario 2, you are in a ship to mars, and you have been trained to count exactly in real time, so you count that it takes 20 minutes to get there despite how it's said that it only takes 10 minutes, then on your way back it's instant. Thanks for reading and feel free to debunk this.

Vor Tag
Aishwinder Singh
Aishwinder Singh

If the backward speed of light is instant then “aliens” looking light years away are looking in real time if Einstein’s convention is true aliens still see dinosaurs

Vor Tag
Gar Harris
Gar Harris

use a third clock equidistant from the first two to sync them with each other by exchanging lasers with them. it may end up different than the 1st 2, but they should end up the same.

Vor Tag
fleetadmiralj
fleetadmiralj

Okay, let's say we had a person on Mars, and we said we were sending a signal at precisely X time. Sure, our clocks might be out of sync due to the travel, but they wouldn't be the time it takes light to theoretically travel to Mars out of sync. Wouldn't the person on Mars be able to tell by the time it takes the signal to get to them vs. the *expected* time for the signal to get to them whether the speed of light going one way is faster? In other words, this seems like a testable problem. You just need to be far enough apart so that the de-syncing of any clocks is an order of magnitude or two from a detectable error in the speed of light. I suppose it wouldn't definitively prove that light traveled exactly the same speed, as the desync would always present some margin of error, but it seems like it could eliminate any *major* difference in the speed of light going different directions.

Vor Tag
Mintu Saren
Mintu Saren

Hypothesis.

Vor Tag
Robert Hund
Robert Hund

The Mars 20 minute round trip is interesting, because if we know the distance between the two stations when the message is sent, and you can measure, using C, exactly how long the message should take, you can synchronize the clocks pretty accurately. And let's say they are both atomic clocks, so that they will stay really really close to synchronization. Using the convention in the video of light being consistently faster in a single direction, like it's "windblown", once Mars and Earth are back together on the opposite side of the sun, you just do another synchronization test, and if there is any significant difference in the speed of light in that direction, then when Earth sent the "it's noon" measurement, it wouldn't get to Mars at 12:10 as expected, as it would be traveling "downwind", where earlier it was travelling "upwind". Now, if the issue is that gravity is acting on the speed of light, then "upwind" would always be from Earth to Mars (going away from the sun), so you would also have to do a test when the planets are close to opposition, so sun effects would be mostly cancelled out. To be honest, I think this argument is a bit crazy. Light isn't bidirectional like is being presented in this video, it travels in 360 degrees, or more accurately 41,253 square degrees, and if the speed of light went faster in one direction, there would be some varying kind of effects in every other possible direction, wouldn't there?

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Robert Hund
Robert Hund

Maybe this is just simple, but what about a simultaneous two way and three way speed of light test? Put two clocks at opposite sides with mirrors, send one beam of light that bounces once and measures the two way speed of light, but the returning light also bounces back to a clock on the other side, and do this in both directions, so that you get both a two way and a three way measurement off the same beam. The two way measurements can be used to synch up the two clocks, leaving the measurement of the third leg as the one way speed of light, unless there is still a relativism issue when looking at the two clocks. If I were a physicist I might know that, but I'm just a guy with two clocks and a flashlight.

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TheChillBison
TheChillBison

What if you could sit say on the point of an equilateral triangle with two synchronized clocks at the other two points, and imagine you have a controller connected to both clocks. You could test their synchronicity by pushing a button on the controller that would pause the clocks. If they're stopped on the same time, you would know they're in sync, right? And then once you have that established, you set both clocks to start and the laser to fire at the same time, say 8am. Both clocks stop when the light passes them. Wouldn't that give you a one-way time between the clocks?

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Elan Wan
Elan Wan

Couldn’t you definitively prove or disprove the idea that light travels in different speeds in multiple directions by just having a clock between two clocks fire a pulse to both clocks and then just observing whether each clock is in sync? (Similar to the one at 9:45)

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S M Shah Riyadh
S M Shah Riyadh

How about we use quantum entanglement for triggering the clocks? We will be able to communicate faster than light and measure the speed in one direction!?! Maybe i am wrong.. lets discuss.

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GC PH
GC PH

Great are the works of the Lord, studied by all who delight in them. Psalm 111:2 ESV

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la absenceofcol
la absenceofcol

In the end it's all relative I this constructed reality of the dual realm. You are light. Light observing light. The dreamer observing the dream.

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you can use a large amount of mirrors put at certain angles so that the light will make a full circle and go back to the first clock. of course we cannot be 100% sure that every little change in the direction of the light will affect its speed too.

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JumpingTomato
JumpingTomato

Although this pure theoratical, maybe this might work to truely measure the one-way speed of light. It's clear we can only use one clock, and lighe need to go one way. The only way to accomplish this, in my opinion, is to let light go in orbitm There is one place in the universe where this actually happens: in the photon spheres of black holes. If you could somehow place a clock there somehow, which could only pick up on your own beam on light, might that work?

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hetspook666
hetspook666

If this is correct than in theory its possible to go faster than light and still not go faster than the speed of light..

Vor 2 Tage
Yawar
Yawar

dude I was having a normal life before watching this video :/

Vor 2 Tage
Nathan Hebbrecht
Nathan Hebbrecht

Can’t you sync both clocks with entanglement?

Vor 2 Tage
Anders Söfting
Anders Söfting

I guess this is already thought about, but why not send something else at the same time, something measurable, and compare the time delays between light and the other "thing" on the recieving end. Then send them back and compare results. Since there is a reference you can tell whether light changes it's speed or not.

Vor 2 Tage
MADLUCYtheQUEEN
MADLUCYtheQUEEN

You cannot measure the speed of light with time as time bends when travels at the speed of light 💡

Vor 2 Tage
MADLUCYtheQUEEN
MADLUCYtheQUEEN

Think of stars n from when a star is born to how long it takes to see the star from earth as we don’t see it straight away .. I guess that’s another way maybe to measure from light coming towards us .. I ain’t no scientist this just thought experiments and bless your page I just found your vids yesterday been watching ever since 🙏

Vor 2 Tage
李辉林
李辉林

用我的“客观真理理论”解释这些所谓人类一个世纪来创建的“人类现代伪基础科学理论体系及那些最高伪科学难题”,不是如讲解违反了客观、普遍、永恒存在地科学常识一样地轻易的被推翻否定? 据报道:【科学家发现最遥远的星系,在宇宙中旅行了134亿年的星球被科学界捕获。】 评论:此报道带给人类的真的是惊喜?还是更多更大地疑惑? 首先、说宇宙是无中生有、由“能量变物质”大爆炸地产生了138亿年,人类已经看到了134亿年前的情况。这么说、人类就应该能够看到的是134亿年以来宇宙地连续不断地变化情况?除非宇宙发展是片段、而非连续的,起码应该能够拿出局部连续变化的宇宙时空证据吧? 其次、说宇宙从大爆炸以来都是呈膨胀发展的,这符合爆炸的现象。但是一个大爆炸持续膨胀了138亿年,其所产生的物质就算是有先后,总不会都是瞬间由能量变物质、又由物质还原成什么都找不着的能量地吧?起码人类所生存的地球就不是瞬间那样变化的。那么宇宙中所有物质的运动变化轨迹,就应该是呈放射性的,不管是线性的、还是非线性地几何变化规律,人类看到的就都应该是一条条数以亿万年呈放射性、连续地星光,所有的光线都应该统一地指向宇宙爆炸的核心。 再次、人们所看到天空中的繁星点点,既然是若干亿年地连续暴光,这就说明:那些星球的光体是实体地若干倍,而且那些星球从来都只是在那个光体中运动、变化的。宇宙的真实时空并不是人们靠一种常人无法看到的超级“仪器”、才能“看到”认为的那个样子,没有宇宙大爆炸的痕迹、是被人类膨胀的。更不可能是由那些“智慧人类”自创一个“量子”将:能量与物质相互转化,“无中生有、有中生无”地魔术出一个宇宙! 仅此三条评论,足以提供人类对宇宙观地重新思考。 据某科学报道:发现了宇宙中有两块星云发生了相碰撞?那么其星云中拥有上亿的星球怎么都没有发生碰撞?这也证明了我的“宇宙客观真理理论”:组成这些星球的同样是由原子三基本物质组成放大的物理层级及其万有引力与万有斥力结构关系,所以在星云发生碰撞(交会)时,两块星云的星球彼此都是在其万有引力与万有斥力同时作用下,保持着相互地距离而安全地通过,却没有发生碰撞爆炸的。 近半个世纪,一个全身残疾,却头脑绝顶聪明的人,让全人类四支健全的科学家们一个个都头脑残缺(面对我对:光速只是电及所反应出的光、磁物质结构运动的专利,人体不可能乘上“电、光、磁去做光速飞行。“光速飞行器”及“宇宙大爆炸”都是违反自然科学地反证,他能够承认他的主观猜想不科学,并宣布自己的生命结束。而那些靠猜想欺骗人类获得了一切的精英们却仍然还是念念不舍,仍然想依靠杨振宁等用伪科学骗取获得的“人类最文明代表头衔”,投靠与政权邪恶统治相互勾兑继续伪科学、伪政治制度共同欺骗人类。)?我用宇宙(完全是由不可消灭也不可创造出,有限的量及具有无限地排列组合变化。)的三基本物质:电子、中子、质子永恒地存在普遍性,特性,运动,相互关系解释了所组成地原子、分子、、、直至整个宇宙。你伟大科学家丁肇中认为这只是些过时的“基本物质”概念?取而代之的是“量子”“夸克”和“胶子”(据说是半个多世纪来,已经又创造、发现了两百来个更基本的“粒子”。甚至“发明”出篡改自然规律的“暗物质”“暗能量”“反物质”“反能量”?是将他们用睛眼怎么都看不明白的事物,就智慧地指导人类用屁眼去观察,只要有权有势一切不就想怎么解释就能怎么解释了?要永远地用若干个猜想去“证明”那个提出的原始猜想!)。那么你能够将其消灭或创造出吗?用你的“物质”来解释其在宇宙中的普遍存在及共同作用组成了宇宙地物理关系吗?就像劳动者用一些基本材料组织修建成了紫禁城,你们中国文化传人却一口咬定:那只是没有文化的人地低级作为。你们自己在紫禁城里随手弄来一些粉尘,就有文化地宣布:这才是组成紫禁城最基本的东西!想将人类对客观世界的认识引向中国式的炼丹术?想再让全人类比你们更脑残?有没有“量子”“夸克”和“胶子”都已经能够解释客观大自然(靠分子、原子都不能解释整个大自然的存在,只有组成他们的基本物质与结构原理才能解释宇宙的存在地共同法则。),有了只是更进一步深入了解,并不是要颠覆·推翻。中国文人的存在意识,都是皇权强盗意识。所以中国的统治历史文化才是颠覆轮回地周期律。 知青大叔二 +李辉林 对科技东西。我真是看不懂 李辉林 +知青大叔二 其实最科学的就是最客观普遍存在的。 1、汽车运动理论,是在固定动力能量范围内,靠调整其驱动力与驱动速度地相互转换关系、来适应客观环境条件地行驶。可中国伪动力科学理论却是:靠增加动力(如同更换不同的发动机)的能量大小(倍量差),去完成实现比别人高百分之几的“国际领先”地速度。 2、不要被“宇宙物质结构动力能量学”(演变论)的无穷大理论给搞蒙了,宇宙中所有的物质都是由正(质子、中子)负(电子)物质及能量、结构、运动、变化所组成的(就像电子计算机仅仅只是地球人依靠利用了自然界中,最微小一部分的电子地得失:“1”与“0”这宇宙最简单普遍的物质关系及变化规律,就可以计算、记录、模仿、设计出最为复杂的事物与客观自然世界现象。)。现实科学理论认为:物质具有“万有引力”,所以电子围绕质子中子转、月亮围绕地球转、地球围绕太阳转动、、、、、、!那么物质如果只存在万有引力,电子就会被原子核吸引在一起、月亮就会被地球吸引在引起、地球当然也要被太阳吸引在一起,整个宇宙中所有的物质不都会被吸引成一个没有任何空间运动的奇点?所以这个“万有引力理论”是不客观完善的,必须存在一个与之抗衡、互补、共存的“万有斥力”,才会将宇宙物质激活、运动、展开成现实的样子。 我的创新动力学理论就是这样从发现、现实的应用动力学理论的“力不平衡”现象中,发现了人类基础物理理论的不足之处,而提出了可以包罗整个宇宙更为客观、普遍、可证地理论基础。是不论有无所谓专业科学知识的都能了解认识的,就像当年人们了解认识牛顿提出的“苹果落地”一样,只是在他的认识上更客观完善了。当然对于搞更专业深入的分枝,是必须要有专业知识才能进行的,就像轮船、飞机、火箭同属于动力学分枝,需要不同的专业人员,但是他们一定是在同一个共同地动力学理论基础上展开发展的。即使《相对论》提出了“不同参照系”的认识论,但是在对动力物理的认识上,是继续了其“物质运动能量不平衡”地不足的。 希望能够像“苹果落地”样能够被认识接受。只是苹果落地时、怎么没有出现“万有斥力”(与两物体的质量成正比,与两物体间的距离成反比,方向相反、呈离心力。)?那是因为与地球的万有引力比,苹果的万有斥力太小太弱,它不是月亮,完全被忽略不计。同理、如果在月亮的位置上只是一只苹果,因为其质量太小、与地球的距离又太远,地球对它地“万有引力”(与两物体的质量成正比,与两物体间的距离成反比,方向相同、呈向心力。)也就弱小得忽略不计,只能认其在太空自由中翱游。(2016年2月26日)

Vor 2 Tage
TheFisheyfishey
TheFisheyfishey

Question: If there is so much uncertainty regarding the actual speed of light, shouldnt we be focusing on find the possible differences in the speed of light ? if A to B and B to A are arbitrary yet proportional, is it the same in all directions ? Are those directions following conventional NESW directions? is it a matter of "going" light and "returning" light ? Arent these the kind of questions that should be asked about lightspeed ? We know that c is a convention, but if we assume that its wrong, what would we observe, and can we verify those observations according to scientific reasoning ? Great videos, got me racking my brain pretty hard tbh.

Vor 2 Tage
Valeska
Valeska

And what if we build a really long clock to measure it? XD

Vor 2 Tage
Rob Timberlake
Rob Timberlake

Once we can transfer Qbits of info from Earth to Mars and vice versa and compare to our then outdated light transfer methods, we should know. Quantum teleportation would get us there would it not?

Vor 2 Tage
notoriousSKP
notoriousSKP

Now I feel like I'm going to let my ignorance show but if we were to quantumly entangle a couple particles and moved them a distance apart, then measure the time it takes light to go from one particle and hit the other and back the other way with a separate beam wouldn't that work? I mean one particle should show the effect of the light on the other particle instantaneously.

Vor 2 Tage
John Millican
John Millican

What would be the outcome if we started with three synchronized clocks, then move two clocks in the same direction from the center clock at the same rate of speed stop moving the first clock when it has traveled exactly 1 kilometer and stop the second clock when it has circumnavigated the globe up to the point where it is exactly one kilometer from the center clock. Could we not then fire the laser in both directions simultaneously and measure the time it takes the light to reach the two clocks. Could we calculate the proper time differential caused by the second clock moving at the same rate as the first clock but for a longer period of time? Or, even use a fourth clock that continues at the same speed as the other 2 moving clocks all the back to the stationary clock giving us a reference for the time dilation. Obviously I am NOT well educated in this subject but I thought why not ask.

Vor 2 Tage
dark shadow
dark shadow

When you see the clock the light reflect from the clock then you can see it means we really cant calculate the speed of light 😂

Vor 2 Tage
milesying
milesying

Couldn't we test to see if the speed of light changes becouse of directions just by moving two clocks away from each other at the same speed and time. Then you just check if the clocks change time.

Vor 2 Tage
Nandakumar Menon
Nandakumar Menon

Note also that the clocks start ticking only when there is no relative motion between them, i.e when they have physically stopped moving.

Vor 2 Tage
Nandakumar Menon
Nandakumar Menon

How about this? A device with a clock (set to zero) is set up at point A. This device can fire identical lasers in opposite directions simultaneously. We get two more identical clocks set them to zero, and keep them switched off. They are mounted on top of on two identical cars which travel in opposite directions at the same slow speed like 1 cm /sec (maybe light has different speeds in opposite directions, but we can ensure that cars have the same speed.). When the cars start, the clock at A is started. At 1 km from A on either side, say at B and C, are structures into which the clocks will snugly fit as the cars pass below them. As soon as they are deposited, the clocks start ticking and are in sync ( but we have not used light to sync them). When the cars reach B and C, the time at A will be 1000 /0.01or 100000 sec. Let us wait for another 1000 sec, and then fire the lasers simultaneously towards B and C. The clocks at B and C are configured to stop when the laser beam hits them. If the speeds of light in directions AB and AC are different, the readings on the clocks will be different. The defense (or should that be the prosecution?) rests. Note that we did not have the cars travel back to ward off arguments that their speed is different in different directions, and the clock at A is only to wait long enough to ensure that the clocks at B and C have started ticking and already show some time. Like I mentioned in a previous post, we could always argue that length, speed and time are different in different directions, but we will never know as the devices will align accordingly. The argument that we can never find if speed of light is different in different directions was based on the assumption that the clocks had to be synchronized using light which we have sidestepped.

Vor 2 Tage
Will Hastings
Will Hastings

How does this interpretation effect the concepts of light cones and Minkowski space? Sure I can understand we can't directly measure the one way speed, but how does there being a directionality to the speed of light impact our other models and causality, time dilation, etc...? If we think of the speed of light as the speed that all objects move through space-time only in the dimension of space, then doesn't a directionality of the speed of light imply the directionality of the speed of anything through space? How would that effect gravity and other forces?

Vor 2 Tage
Pradeep R
Pradeep R

How about a 3 way reflection and remove two and get one?

Vor 2 Tage
Aadithyan Raju
Aadithyan Raju

Can't you start clock "A" when light is at distance 0KM. Then start the Clock "B" when light is at distance 1KM. Then at a point take the time difference to find the time taken for light travel for 1 KM.

Vor 2 Tage
Aadithyan Raju
Aadithyan Raju

@Kyle G. why don't you set up a mechanism with only mechanical means so that the time dilation won't happen, like a long rode with applying pressure to stop the clock.

Vor 21 Stunde
Kyle G.
Kyle G.

How do you record the difference? Stopping both clocks simultaneously is impossible next of the distance, observing them both from any point incurs a delay, and bringing them together makes them experience time dilation. Unless I'm wrong this is the same problem as trying to start both clocks simultaneously.

Vor Tag
steve tapping
steve tapping

ok, hear me out. how abouuuuuut... the original experiment, but with an 8 mile long axle, (obviously this is a thought experiment, but should still be experimentally possible with a shorter distance/enough money) and an identical cog setup just before the mirror. if the speed was slower than we thought in one direction, it should impact the visibility of the beam, no? someone explain why this doesn't work, as I'm sure this is not an original idea :P

Vor 2 Tage
EpochRazael
EpochRazael

OK, so what if we put a probe out in deep space say like a light hour away, and sent a command to it to immediately change course as much needed to make a measurable adjustment, and then measured its trajectory to see if it had made the maneuver at the expected hour, or two hours later. Surely this could be possible? Please someone call me out where I'm wrong.

Vor 2 Tage
Xexorian
Xexorian

What you're trying to measure is the acceleration of local spacetime in a vector pointing outside of it. What about measuring light travelling in different geodesics such that we can attempt to figure out the shape of spacetime? Could we measure these changes by testing different 2 way vectors using the positions of our changing path around the sun or galaxy?

Vor 2 Tage
Antoine
Antoine

this guy better be careful, using his logic, he just might make a case for Gods existence lol

Vor 2 Tage
Cedric Story
Cedric Story

Exactly! He said a mouthful when he said that some things in the universe mankind can't figure out!

Vor Tag
Qchns Garage DIY
Qchns Garage DIY

We need Wormholes...

Vor 2 Tage
Samaila Abdullahi
Samaila Abdullahi

I am forever grateful to Dr IGUDIA on YouTube who cured me from herpes with his herbal medication, you are so real and trusted.

Vor 2 Tage
karga makes
karga makes

Isn't this easy to measure using mirrors? Just an idea. You're talking about round trip of light going from A to B and back to A. So what if you use mirrors and go A to B to C and back to A. Distance is different so you can calculate the difference and have the light speed for each section A-B, B-C and C-A. How would photon "know" that C-A is the trip back for it to have infinite speed? If it had infinite speed, it would have infinite energy since energy of the photon is speed of light times momentum. So it would just create infinite energy from nothing? Doesn't make sense. If anything photons lose energy when they bounce back to the source because their momentum is smaller. How much energy they lose depends on what they interacted with, so this also could be used to measure how much energy is lost in a photon. Or maybe at the time of the photon bouncing at point B, send another photon from B to A and see whichever comes first.

Vor 2 Tage

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