Why No One Has Measured The Speed Of Light

Birt 31 okt 2020
Áhorf 6 494 402
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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., & 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., & 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., & 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"

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  • Truth BeTold

    Truth BeTold

    2 mínútum síðan

    What If we shot out an astronaut in every direction and told them to return at a specific point in their journey. They would all get back at different points in time... Right? Somehow use this to discover times speed?

  • Bowen Creer

    Bowen Creer

    29 mínútum síðan

    What if you had two beams of light going in opposite directions triggering two clocks?

  • Babak Vaezi

    Babak Vaezi

    Klukkustund síðan

    Always felt like there is more to the speed of light.
    Awesome thinking and looking in new directions.
    “How about light speed from a moving source ?”
    “Maybe there is a positive and negative light “
    Like magnets.
    Black holes are maybe negative speed of light, and opposites attract.
    Maybe I know too little 😁
    But you are a great mind

  • †РаБоТяГа_ ek_FaStbik†

    †РаБоТяГа_ ek_FaStbik†

    2 klukkustundum síðan

    And what if you take one timer, move it away from the other, look at the error, take a third timer on which the error of the second is increased by 2 and move it in the same direction at the same speed, and at the time of connection, these timers are synchronized with 1😊

  • The_Animal

    The_Animal

    2 klukkustundum síðan

    one of those videos that you get it but you still dont know crap

  • Vincent Trotot

    Vincent Trotot

    2 klukkustundum síðan

    What if Marc and an observer on earth had some very powerful telescopes 🔭 ? If the speed of light is different depending the way light is travelling, wouldn’t they see that their watches are out of sync?

  • wefinishthis now

    wefinishthis now

    2 klukkustundum síðan

    Our inability to measure the one-way speed of light sounds eerily similar to our inability to properly observe whether light is a particle or a wave, so my thoughts are that the two problems are probably related. Since light's round-trip time is not actually about the speed of light, but the speed of causality, perhaps there's a way we can cheat by measuring other mass-less particles (which also travel at the speed of causality) to measure the one-way speed of light?

  • Rishi Achaibersing

    Rishi Achaibersing

    3 klukkustundum síðan

    Could gravitational forces be influencing the one way speed of light?

  • praharshitha josyula

    praharshitha josyula

    3 klukkustundum síðan

    wouldn't light travel through the path which takes the minimum time ?

  • ARUNBAL VICKY

    ARUNBAL VICKY

    4 klukkustundum síðan

    Out of the box thinking ❤️

  • Ronnie

    Ronnie

    4 klukkustundum síðan

    Could it also be, that light is less than 1/2 c in one direction and more than infinite c in the other direction, so ist travels back in time?

  • Hirnriss Lp

    Hirnriss Lp

    5 klukkustundum síðan

    Dumb question: What if you then wait, until Mars is at the other side of the earth and send the signal again. Let's say Mars is 10 Minutes back and the signal is infinitely fast in one way. It's 12:50 at earth and 12:40 on Mars. They send the signal, "hey, it's 12:50", and this signal instantly reaches Mark, then he would recognize the error.
    Only thing I'm not sure about: He travelled faster than the earth to reach the other side of our solar system. But doesn't that mean, his time went even slower than the earths?

  • Sg ///

    Sg ///

    6 klukkustundum síðan

    We should do multiple calibration of time from earth-mars. You calibrate once and then verify your theory...send a message from earth to mars, calibrate and respond from mars, then immediately send a second mesaage with the time when the message was received .. We should know if einstein was right or wrong

  • johnny hart

    johnny hart

    7 klukkustundum síðan

    this is why I will always trust and have faith in Jesus Christ

  • Elliot Lin

    Elliot Lin

    7 klukkustundum síðan

    The problem with your argument is simple: If light isn't consistent in both directions, then it violates the principle of relativity. The speed of light HAS to be constant in any direction in order for special relativity to work.

  • Nick Smith

    Nick Smith

    7 klukkustundum síðan

    Question... Is there not a way to use a T layout with a neutral clock? Lets call the top left of the T (A), and the top right (B). While the bottom will be N for neutral. Break the line from A to B exactly in the middle and put your mirrors to reflect to N and sync both clocks for A and B to N. A and B's one way trip to N and or vise versa should be identical. From that point just continue the experiment, Removing N and only going from A to B and B to A. I really have no idea here... but that popped up into my head.

  • Mario Portillo

    Mario Portillo

    8 klukkustundum síðan

    Tell me if this is dumb but it's just an idea get a really long plank of wood or whatever can stay straight for a long time and put one small square of glass at the start of the plank and one at the end then then shine a laser through one end and line it up with the other piece of glass and put some sort of sensor in the glass then goes off when I senses light you could measure the amount of time that it takes between One sensor to go off and the other and determine how fast it's going

  • Kara0ki

    Kara0ki

    8 klukkustundum síðan

    This is all nonsense. c = c. (regardless of the direction of travel) If c changed depending on direction, you would have blue-shift in one direction, and red-shift in the opposite direction. It could be measured and quantified.

  • Stephen Paul

    Stephen Paul

    10 klukkustundum síðan

    I think that while in theory you could have an infinite number of models for how light moves in the universe, it is more useful to use a simpler and more consistent model, so long as it remains consistent with all our observations of the universe. Most things that we recognize as proven fact could in theory be completely fade perceptions, but so long as they are consistent with all observations of reality, it remains practical to assume that we’ve proven them true.

  • radiodurans

    radiodurans

    10 klukkustundum síðan

    So those that think that light might be traveling instantaneously on its return path, do they think this is due to some quantum entanglement principle at work?

  • Ivan Sushkov

    Ivan Sushkov

    11 klukkustundum síðan

    why not put in a third mirror? and let the light in turn from different sides.

  • Isaiah Cutshall

    Isaiah Cutshall

    12 klukkustundum síðan

    Couldn't you connect the switches mechanicly to start both timers at the same time?

  • I Love Pizza

    I Love Pizza

    12 klukkustundum síðan

    I can think of two ways:
    1) Two stop watches are set to start with a delay after x amount of time. Once they are in place then shoot the light beam with perfect synchrony.
    2) Two stop watches are started at the same time/same place. We move one watch at a time at a constant velocity. Once the odometer reads a certain value the watch is stopped. Then this process is repeated in the opposite direction. Both times their face times are matched. If C is constant in both direction then both these watches should have the same difference in time. This method would require extremely high precision in distance and time measurement.

  • Del Scoville

    Del Scoville

    12 klukkustundum síðan

    The fact that earth is moving through space actually makes it impossible if we're measuring a reflected signal. It just won't be travelling at the same speed in both directions. We'd have to find a way to stand still in space.

  • Void X

    Void X

    12 klukkustundum síðan

    At 10:15 he talks about having a center clock to send the pulses out. What if you sent 1 pulse to start and a 2nd to stop it and record the difference. If light travels the same speed both directions then they would be the same when brought back together

  • Hastor

    Hastor

    13 klukkustundum síðan

    If you have two clocks in the first scenario, you could send a light pulse to the second clock, then use like something premeasured like electricity speed to send a signal back. Subtract the time it took for the electricity, and you get the one way speed of light, at least in that direction. Right? The electricity isn't affected by the speed of light, so it should work? I'm probably wrong though

  • I don't know any good names

    I don't know any good names

    13 klukkustundum síðan

    What if you set off an explosion really far away and measure the difference between when you see it and hear it, then do it again on the other side... surely that would work?

  • AVINASH G

    AVINASH G

    14 klukkustundum síðan

    I was so much interested in science, but after watching video multiple times.
    Me: why should I care about speed of light😁

  • AVINASH G

    AVINASH G

    14 klukkustundum síðan

    round way trip speed = 299792 km/s, then
    One way speed= could be
    599584km/s🤣🤣🤣

  • Nick Fox

    Nick Fox

    15 klukkustundum síðan

    Two clocks. They start in the center, centered on the equator with the 1km path running perpendicular to the equator. Then use mechanical linkages to move them BOTH from the center to the ends of the 1km at a fixed, matching speed. Have a light source at both ends. Fire them off, bring clocks back to center, times should match.

  • Alvaro Navarro

    Alvaro Navarro

    15 klukkustundum síðan

    What if we put a atomic clock on the moon? It would look like the clock slows down and then speed up...

  • Dominic Gindoff

    Dominic Gindoff

    15 klukkustundum síðan

    I love the mark watney reference amazing movie

  • Champa Power

    Champa Power

    15 klukkustundum síðan

    I duno, use Sundials instead of digital clocks? lol

  • Siddharth Reddy

    Siddharth Reddy

    15 klukkustundum síðan

    I have a thought, in order to find out the speed of light in one direction. A to B,
    Try measuring from B? To A and C?
    Distance B to A and B to C = B as centre
    For example:
    Like you said if we have a satillite in centre of earth and mars shoots a signal to both sides
    Time taken to earth is different to mars then it proves light travels same speed in all directions?

  • lynn rathbun

    lynn rathbun

    15 klukkustundum síðan

    Can;t be measured , because it is defined, and it defines length.

  • Drift Simulator

    Drift Simulator

    15 klukkustundum síðan

    even if u find way to measure u cant say speed of light is this or this, because it depends on light, not every light are same not every light go so far and so fast , battery light cant move fsater than light from sun :D so all it depends on some power of light, use so low energy to a small light and there u can get slowest speed of light

  • TRONCO0013

    TRONCO0013

    15 klukkustundum síðan

    Si ponemos 3 lásers que disparen al mismo tiempo, y para asegurarnos ponemos un medidor por cada láser a una distancia conocida, el láser A activará un segundo medidor a distancia de x, el láser B activará el medidor de inicio mediante rebote en un espejo y el láser c activará un medidor a 3x. Si c=3a b=2a indicaría que no existe diferencia entre una dirección y otra.

  • abdul_wasay 06

    abdul_wasay 06

    16 klukkustundum síðan

    Put a light source in between a circle of clocks if the clocks show different times for when light hits them we could know if the speed of light is different depending on direction if they all show the same time this means the speed of light is constant no matter the direction

  • Kelton Campos

    Kelton Campos

    16 klukkustundum síðan

    Wow so we could theoretically be seeing everything In the present rather than the past? The agreed upon speed of light could be wrong?

  • Filip Hoggen

    Filip Hoggen

    16 klukkustundum síðan

    What if you use 2 syncron clocks in the middle and send them to opposit sides with the same speed. The clocks have agreed tgat the light will be sendt on a spesifik time like 10s. So the clocks will count the time between

  • J B

    J B

    17 klukkustundum síðan

    what if people on earth have really strong telescope and can watch the person on mars from earth? if light takes 10 minutes to get to mars, the people on earth would see the person on mars write down the time at 12:10, but if light takes 20 minutes to get to mars, wouldn't the people on earth see the person on mars mark the time 12:10 when the time on earth is 12:20 and know to correct it? or does that fall into the same problem? idk my brain feels like mush right now

  • Russian Bot

    Russian Bot

    17 klukkustundum síðan

    That's just visable light though right? The rest of the spectrums travel at different wave lengths this different speeds I would presume.

  • Banks Kaye

    Banks Kaye

    18 klukkustundum síðan

    Does anyone know if measuring two quantum entangled particles that changed polarity when a light beam hit them would work? Since the one at the end would instantaneously trigger the one on earth and let them know when the beam had hit Mars in real time?

  • jackson schmitt

    jackson schmitt

    18 klukkustundum síðan

    "how do u know FORSURE that the earth is round"

  • joel rogers

    joel rogers

    18 klukkustundum síðan

    What about an experiment where you are in a vacuum have an observer in the middle and two people on either side both equally far away with lights. Both of the light bearers have come to an agreement on 2 oclock for when they turn on the lights and the observer records the difference. Please tell me if this is an unreliable experiment or what doesn't work.

  • Zealot

    Zealot

    19 klukkustundum síðan

    When the astronaut comes back to Earth, wouldn't they notice the time isn't in sync? Following that logic: there should be a 10 minutes difference between Houston time and the synchronized time?

  • kevin ncube

    kevin ncube

    19 klukkustundum síðan

    A mirror may suffer some latency

  • Yuriy Kryvoruchko

    Yuriy Kryvoruchko

    19 klukkustundum síðan

    I cant even imagine what the conversation would be like between Einstein (if he would be alive today) and Veritasium 😂

  • WolferDub Jazz

    WolferDub Jazz

    19 klukkustundum síðan

    i might have misunderstood the WHOLE video altogether but could this mean...
    1. Events that happen in Earth and in space eg an eclipse or the celestial alignment of planets could have happened before we perceived them because if light doesnt travel at the same speed in different directions, this means that our perception of events might be totally different than our estimated or 'accurate' times.
    2. If we technologically advance, we can measure the speed of light by trapping it in a black hole and building mirrors that have sensors built in around it, and, from the point of light entering the BH(black hole), record the time it takes for a ray to hit the sensor mirror
    3. Since our very eyes rely on two way light or that for us to see, light has to go on an object and return to the eyes, we are unfortunately uncapable of coming up with a way to measure the speed of light and thus base future experiments on possible animals' eyes or machine life...though i must admit this is quite dark

  • Roger Phelps

    Roger Phelps

    19 klukkustundum síðan

    I have news for you. The speed of light has indeed been determined using one way measurements. In fact the first estimates of the speed of light were made using one way measurements. The moons of Jupiter are often eclipsed by the planet. If the distance between the Earth and Jupiter was constant the intervals between successive eclipses should be fixed but, since the Earth and Jupiter are in different orbits around the sun, the distance between the planets is constantly changing. This means that eclipse times, as measured on Earth, are sometimes early and sometimes late. The orbit of Jupiter can be determined using Newtonian dynamics together with parallax measurements of objects such as asteroids that pass close to the Earth. Given the orbits of Jupiter and the Earth the distance between Jupiter and the Earth can be determined. The speed of light can then be determined from the eclipse timing data. Note that different eclipse times are measured for different Earth to Jupiter directions, but the different directions no bearing on the results so this is a demonstration that space is isotropic.
    This was the way in which the speed of light was first estimated. The accuracy of this method will be limited and certainly a lot worse than modern methods. It is, however, a very strong pointer to the speed of sound being the same irrespective of whether a one way or two way path is used and also to the isotropy of space.

  • Himanshu Agrawal

    Himanshu Agrawal

    19 klukkustundum síðan

    I have an thought ( in laymen term) the light move faster towards the object have higher mass, resulting in high gravitational force ( exp. Black holes) so when we sent the signals to mark at mars the time required was high due to lower mass of mars but when her replay back it will come faster due to Earth's mass, also if we add the sun gravitational force the message will receive faster , this just an idea i can wrong

  • Robert Gruener

    Robert Gruener

    19 klukkustundum síðan

    This is probably stupid, but couldn't you have a set up like that at 2:14, so 2 clocks a distance apart but both start when hit by the laser? Then the difference between the clocks would be the time it takes for the laser to travel the distance. The clocks would continually count up, but at any time you could still take the difference (using cameras, etc). Or program the clocks to stop via a sound wave that starts at the middle or I'm sure many other clever ways to get them to stop without light being involved so that you could get directly at the time the light took.

  • AdamGa92

    AdamGa92

    20 klukkustundum síðan

    @veritasium if c in one direction was c/2 we would see half of night sky shining becouse of all of those stars which light didnt come to us yet.

  • Andrej Celko

    Andrej Celko

    20 klukkustundum síðan

    I am wondering, you mentioned to sync the 2 clock in the middle [kind of end of video], but I am pretty sure you could try to sync them lets say 3/4 vs 1/4 way [so not in the middle] and do a measurement, if what you measure using the syncing in middle and what you measure when syncing not in middle gives different results, it is a proof that the speed there and back is different, if you measure the same result it is a proof the speed is the same, I think.

  • Dawid Kaminski

    Dawid Kaminski

    20 klukkustundum síðan

    Use fibre create big loop you can measure one way

  • Rani

    Rani

    21 klukkustund síðan

    cant we use the problem of time dialation itself to solve the problem?
    okay i was gonna propose another solution when i wrote the first sentence, but now i thought of something else,
    when we start two clocks at the same place at the same time like at 2:43.
    cant we start moving clock B, and since B is moving towards the other side at a constant speed, (or that we just know how much time its going to take to get there)
    lets say for example 1 minute. and we stop both clocks.
    so we sync them up
    start moving clock B to the right knowing that its going to stop after 1 minute, (each clock with relative to itself, since one minute is one minute (right?) even if clock A still sees clock B as moving it stops after 1 minute anyways (because of time dialation).
    stop both after 1 minute (when B finishes traveling)
    and we get the clocks back together to see how different is the time, and using that we can tell what is the speed of light in that direction.
    the only thing that im not sure of is that both of them have to stop after 1 minute of being separated, which im trying to say is "absolute time" when each of them counts it in their own local time,
    and without relation to its perspective.
    as in from a 3rd perspective, looking at both clocks from far away, would they stop at the same time? idk

    • Rani

      Rani

      21 klukkustund síðan

      okay nvm i remembered that then they would both have the same time on them because the minute itself would run differently in such a way that at the end they end up with the same time

  • Anubis __117

    Anubis __117

    21 klukkustund síðan

    What if we synchronize the clocks using (when it finally becomes possible) quantum entanglement?

  • Fred Nimzowi

    Fred Nimzowi

    21 klukkustund síðan

    you're overthinking this, really. Make any of your tests with the 2 clocks more or less syncronised, then make it in the reverse direction. And you'll see the difference, if any. And if you have not your answer right there, you at least have a basis to move on from there.

  • Creaters Refrigmenting & enjoy

    Creaters Refrigmenting & enjoy

    21 klukkustund síðan

    Well in the situation of the three clock we can measure the light speed through every angle (between line joining the two detectors and the line joining the detector and the clock) and can see if light speed is all the same.

  • Creaters Refrigmenting & enjoy

    Creaters Refrigmenting & enjoy

    22 klukkustundum síðan

    Well we can use three clocks instead in order to synchronize the the clock seperated by some distance we can place a third clock at the middle point and perpendicular to the line joining the two detectors those are connected to the clock and may be at some time it sends a signal to the two detectors now as the distance between the clock and the detectors are equal the signal recieved by both are recieved at same time and so the two clocks are synchronised now we can do our experiment and can find the one way speed of light

  • Electrify Productions

    Electrify Productions

    22 klukkustundum síðan

    What if you curved the path that the light travels on so that the light starts and stops at the same place?

  • PRANAV

    PRANAV

    22 klukkustundum síðan

    if u suppose that speed of time isnt always the same then time dilalation doent even work

  • Ariea Ilezion

    Ariea Ilezion

    23 klukkustundum síðan

    what if we bounce the light off of multiple different mirrors back to the point? it wouldnt measure one way speed but if c is different it proves that c isnt the speed of 1 way light speed? not sure tho

  • Nivyan

    Nivyan

    Degi Síðan síðan

    Something clicked. Here's a weird theory:
    1) We, and everything in the universe are in orbit of something at the centre
    2) The difference of the pull is so small, that we don't have the tools to detect it within the furtherest reaches we've ever gone.
    3) If this is the case, we wouldn't know if going in one direction is vastly faster than going in the other. From our perspective, we've never experienced everything else.
    3 Tangent) We're so rare in the universe, because not only is our planet ideal - but moving much closer or further from the orbit, has effects that render life unable to sustain itself. In other words, we're in a tiny, tiny pocket of the universe where (our type of) life is possible.
    4) Furthermore, if 1 and 2 are correct, information could travel exactly like described: Very slow if directly opposite the centre, then essentially instant if fired directly at the centre.

  • Philip Soares

    Philip Soares

    Degi Síðan síðan

    What If you start with 3 perfectly sincronized clocks, 1 in the middle, 1 in the right and 1 in the left, the clock in the middle sends two laser in the same moment in both ways, when the laser hits the clock(left/right) it stops. Maybe that can measure the speed If light in one way around

  • _

    _

    Degi Síðan síðan

    So if the speed of light were infinite in one direction, would that affect how fast our space ships could travel in that direction? After all, isn’t the speed of light the only limit to the speed of massive objects?

  • Srishti das

    Srishti das

    Degi Síðan síðan

    5:06 wowww🙏🏻👍🏻

  • Saberus Terras

    Saberus Terras

    Degi Síðan síðan

    I've thought about this, and I have an idea on how to get a definitive answer... please break my logic:
    Synchronize two atomic clocks, and then send them both out on probes in opposite directions at the same speed. Program both probes to transmit their time to each other and the base station after they reach a proscribed distance. Both then transmit the other's message and the time it was received to the base station. Repeat to cover the 3 axes of normal space. Any discrepancy should become apparent pretty quickly?

  • EnchantedGamer9

    EnchantedGamer9

    Degi Síðan síðan

    Thought Experiment here, feel free to debunk it.
    There may be a way to determine not the one way speed of light, but if light is faster going one way or another.
    Imagine you are a 10 lightyears away from earth, and looking at a clock with a telescope. You are stationary relative to the clock, so you see exactly what happened 10 years ago by the second (assuming that the light speed c constant from earth to the telescope.) 10 lightyears can be versatile in the scenario and the speed of light does not have to be C for the experiment to work, but I will use these values for the thought process.
    Now imagine that you start to move towards the direction of the clock, your hypothesis could be that the time on the clock will start to speed up relative the speed at which you travel towards the clock and the value of the constant c. If it does not, it proves that the one way direction is not the constant c.
    I'm not too keen on the idea of time relativity and if/how it would affect this excitement.

    • EnchantedGamer9

      EnchantedGamer9

      Degi Síðan síðan

      I also want to ask why would the speed of light be different in certain directions in the first place. Assuming that light is still a piece of matter, some force would have to be working on it to cause this discrepancy, which I think makes perfect sense. The force of gravity is infinite, and other forces for that matter, and I'm sure the universe ends at somepoint, so gravitational force should be stronger in one direction depending on where you are relative to the rest of the universe. Fundamentally, the speed of light has to be different in one direction, however, my hypothesis is that the difference is negligible.

  • Jimmy C13

    Jimmy C13

    Degi Síðan síðan

    🤔💭🧠💭😠💭🧠💭🤨💭🧠💭🧐

  • Paul Snow

    Paul Snow

    Degi Síðan síðan

    What about Roemer's experiment? He measured the speed of light in one direction.

  • Andrew Beavis

    Andrew Beavis

    Degi Síðan síðan

    To quote the great DR Emmet Brown, "Marty Marty you are not thinking 4 dimensionally !" The starting assumption is that the speed of light IN A VACUUM is "c" and there is nothing to slow it down, physically so thats it. If you place the light beam in any medium thats not a perfect vacuum, even interstellar space, then the wave slow down minutely as its absorbed and reradiated. Furthermore, the purpose of the Michelson-Morely experiment was to show that space has no preferred direction because there is no "luminiferous aether" present to propagate the wave, indeed it travels fastest in a perfect vacuum. (although I suspect you may take issue with MM - have a go :)) ANOTHER, more relevant source of experimental error is the damn mirror ! Light does not INSTANTANEOUSLY reflect off the mirror , there would be a small time delay while the surface electrons absorbed and re-radiated the energy ! Ole Roemer's experiment gets around this....

  • Saibal Sinha

    Saibal Sinha

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    Measuring anything in universal are assumptions from observations of patterns and repeatable results which are made references by us. This vast universe of infinite energy, our eyes captures an infinitely small band of spectrum of energy called light.
    It is like you are asking a plankton to measure the quantity of water of a pond from which it borns, lives and dies in it🙏🙏
    Its all inside within us.

  • Agnovelli

    Agnovelli

    Degi Síðan síðan

    Maybe I missed something but why assume the way back is instantaneous?

  • Juzoh

    Juzoh

    Degi Síðan síðan

    What if the light takes time to travel one way and instantly get back, because the light has to render textures going the way we are looking at, and 0 time to get back because it was already rendered. Would further support the theory that we are in a simulation.

  • Syl De Vos

    Syl De Vos

    Degi Síðan síðan

    I dont know a way of measuring the exact speed. But coudnt you find out if the speed is different in some directions. You could sync 2 clocks and then move them in different directions. after moving both for the same distance and same speed you write down the times. This way you could compare the dialation and this could comfirm or debunk wether the speed is the same in all directions. Or am I missing something? And then you could possibly account in your clocks for this dialation? idk

  • hd the wise

    hd the wise

    Degi Síðan síðan

    has anyone checked if the makeup of the mirror changes the speed is light slower with different types of glass or reflective surfaces

  • rabbitskywalk3r

    rabbitskywalk3r

    Degi Síðan síðan

    After spending all the time to synchronize the the clock, mark then realized he actually had forgotten to take care of the potatoes he had planted in the greenhouse and eventually died, still not knowing what the single way speed of light was

  • FelonWind

    FelonWind

    Degi Síðan síðan

    Sometimes I feel like these mysteries were purposely crafted just to make us scratch our heads and make a bemused smile

  • Ramon Leon

    Ramon Leon

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    Einstein already dismantled the notion of "now", there is no global time; it's not an open question if it makes sense to talk about "now", we already know it doesn't make sense.

  • Man Kind

    Man Kind

    Degi Síðan síðan

    Is it possible that the speed of light is simply instant without any other variables?

  • Ninj aPigeon

    Ninj aPigeon

    Degi Síðan síðan

    Would the measurement issue still be flawed by time dilation (or something else), if the two clocks were synced using quantum entangled atomic clocks?

  • RAGHAV GAUR

    RAGHAV GAUR

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    Use an other observer at the centre of earth and Mars now you can know the difference between speeds of light in different directions.

  • Rajasekharan Vichattu

    Rajasekharan Vichattu

    Degi Síðan síðan

    All these talks about speed of light and what not ..... When you cant even Pause Time for a second , let alone time travel.
    I wonder if anything good comes from knowing the speed of light.

  • John Powell

    John Powell

    Degi Síðan síðan

    The C is not necessarily constant than traveling faster than the number we associate with is C is possible as it's is not the fastest possible speed of C.

  • Zel matrix

    Zel matrix

    Degi Síðan síðan

    It's nice you did a video on the speed of light and how that might create a nice case example on photos that some how are breaking the speed limit of light. I would recommend you do a bit more investigation into the speed of light and quantum mechanics to make sure your observation and results have merit. None the less, Keep up the good work. :)

  • abba dejo kim

    abba dejo kim

    Degi Síðan síðan

    have satellite between mars n earth n the satellite sending time to mars n earth at the same time so if light travels in one direction this would solve this problem but we all know it takes light to travel to ur eyes or detector if instant means light does not travel but instant in all direction.

  • Fisher St. Amour

    Fisher St. Amour

    Degi Síðan síðan

    If the speed of light was slightly different in one direction the observable universe would be bigger in one direction, no?

  • Character by Integrity Act Honest_Irish

    Character by Integrity Act Honest_Irish

    Degi Síðan síðan

    So you say that the speed of light is not proven and is convection. Yet you claim dark matter exists without the same proven science to make it an object proof. Either be consistent across the board or don’t speak on objective truth.

  • Eldiezzz G

    Eldiezzz G

    Degi Síðan síðan

    Dustins virginass

  • Nithaël Giroux

    Nithaël Giroux

    Degi Síðan síðan

    Light cannot move at an infinite speed because it would require infinite energy to have light moving at infinite speed. E=MC2

  • debblez

    debblez

    Degi Síðan síðan

    The question doesn’t even make sense.
    For light to go slower would mandate everything else go slower, making the slower light indistinguishable from the faster light! Hell, I could call c 1m/s as long as I scale everything accordingly! The main problem with asymmetrical light speed isnt the asymmetry aspect, it’s the variable c!

  • Cheryl Best

    Cheryl Best

    Degi Síðan síðan

    What about the slow mo guys and that camera that actually can film light ? Can you not measure time between 2 points? They actually have cameras that have a high enough frame rate you can see light traveling.

  • debblez

    debblez

    Degi Síðan síðan

    Okay but how would that work? From somebody who is laughably unqualified to talk about this, I will now talk about this.
    Around gravity fields straight lines don’t follow what might look like a straight line to somebody else... point is, if light suddenly starts going slower as it travels in a straight line, there would be some way to know if you were near such a gravitational disturbance, which violates Einstein’s equivalence principle. More importantly, in our curved, four dimensional fabric of space time, there isn’t even a way to continuously define “direction” for every point in space. It’s topologically impossible. It’s like that theorem that says you can’t continuously define direction on the surface of a sphere. There will always be some point where right discontinuously jumps to left.
    Also if light travels slower in one direction, then everything else must as well, else they would suddenly gain kinetic energy. I might be crazy but I SWEAR that would muck up some known scientific observations.
    And what about doppler shifting? Imagine a glowing sphere rocking back and forth. On one side the slower light should be more noticeably shifted, but since it isn’t in practice, must be rocking slower to compensate, which means the sphere must be getting squished! This implies all object should feel a tidal force squishing them every time they move in some direction, which is ridiculous (assuming I haven’t made any mistakes in my logic, which i probably have)
    This also follows from the conservation of energy point I mentioned before this one.
    The biggest reason why I don’t believe this is possible is because I genuinely don’t believe that the beautiful symmetry we see in our universe around us, in not just three dimensions could ever arise from such a fundamental asymmetry. If at the largest scales we see symmetry, and at the lowest there could be some asymmetry, there must be some point at which there is a jump. I, with my limited wisdom and intelligence, can’t fathom what ever could translate one into the other, but that’s just me, I guess.
    I will admit, you were very compelling, but my human stubbornness won’t allow me to believe something so... disgusting? It just can’t be.

  • travis moore

    travis moore

    Degi Síðan síðan

    So I guess you can't have a timer and start said timer as soon as the laser is on and use a cds cell to stop the timer by cutting power to the timer as soon as light hits it?

  • Marcus Cornwall

    Marcus Cornwall

    Degi Síðan síðan

    What if we could teleport instantaneously and send a light in one direction and and teleport to its destination at the same time and measure how long it takes to get therem

    • Marcus Cornwall

      Marcus Cornwall

      Degi Síðan síðan

      @debblez Its hypothetical.

    • debblez

      debblez

      Degi Síðan síðan

      And how exactly do you plan on teleporting?

  • Timothy Short

    Timothy Short

    Degi Síðan síðan

    It is knowable. I can create a experiment to see if there is a difference in directions.

  • EtherealToxin

    EtherealToxin

    Degi Síðan síðan

    16:53 If E=mC^2 is has no constant-variables, then that would imply that the sub-system-investments made into a Photonic-Psion would then define the speed-maximum of the particle-waves of Light, but if we are dealing with Pre-{Forgon/Matter} then there is no mass, especially if relating to a [pre-Gravity-Object Psion], in which case it would translate more akin to E/0, unless the mass of a Photon itself can be measured greater than 0 by way of the nature of how it creates Collision-Phenomenon, but it should not possess mass until the Gravity-Object Aspect is added, which is a higher-development than a mere Photon, even in regards to the same Soul-Tier, so unless you can solve [Divide by 0]:: the dynamic [speed of light] based on how much Sub-souls have been invested into the Pre-Photon substructure, at least while using that equation anyway, would not work.
    To my understanding {[Divide by Zero] == [Divide by Infinity]}, since Oblivion & Everything are tantamount to one and the same, so it would result in an infinitely-near-zero parameter for the value of C when trying to calculate it directly like that; however, it is also to my understanding that [Mathematics is Exclusively that of an Engineering-Field for Finite-Systems], when referred to from within The Theory of Everything, so involving itself with Infinity can be done Abstract-ually, but once applied literally:: its Field of Use is no longer valid.
    Saying it cannot be known is not exactly accurate, but rather just that there is no Universal-Value, as it depends on which Cosmic-Divine soul-stream, relative to its own internal-parameters, is generating it at the time. Relative to each localized-soul-stream:: there would be a constant-value in some context but it would constantly be changing if it is determined by Power-Input into the subsystems, since Soul-Tiers below the Photon's establishment Tier include factors for meditations that increase the sub-soul-capacity within all systems within one's soul-stream. Furthermore, applying Movement to a Photon is not the Base-minimum form of a Photon. The sub-systems of the Photon are in a circuit of constant-motion, you could say, but the photon itself does not require its own movement merely to be stable. So it would be referring to the speed-maximum relative to a uniform Gravity-Well-Flux, but as maneuvering through a flat Gravity-Fabric is effectively impossible, and all fluctuations on the Warp-Fabric would slightly disrupt Time-Dilation based on the Fabric-waves it passes through ... but... why would Gravity-Well-Flux matter to a thing without Mass? Hm~
    Well, the Warp-Fabric itself is not really Gravity-Object generated, but rather Gravity-Objects are just exploiting the pre-existing Fabric, and the Fabric is just an [Illusion-of-Reality's Displacement], so it would imply that the Fabric is pseudo-consisting of Spirit-Fuel, but more literally consisting on Pre-Spirit Meta-Data.
    Such that alterations in Light-Speed through different Fabric-Zones through different so called Gravity-Waves, would either be caused by Sub-souls invested if the Sub-souls contained within are directly correlated to Penetration-Force or Speed of the Phenomenon in the application-design of the Photon itself, or it is based on Illusion-Parameters for the respective Divinity:Reality-Zones in which how they may alter Exotic-Phenomenon whom pass through their Auras; which some Tainting, of the Souls in transit, would at least happen through Equilibrium-Phenomenon relative to the
    power of the Exotic-Divine-Auras in which they pass through on their journey, but whether or not that would effect the speed of the Photon when passing through it would depend on how those particular Photons are constructed; as The Theory of Everything is basically just elaborating that there is no universal Law of Physics, more/less.
    Photons consist of the circuitry-matrix of a Grabbing-Phenomenon and a Localized-Resonance-Phenomenon being interwoven, so to create a Collision-Medium, which is really all that a Photon is.
    As for determining its Raw-Parameters beyond Collision, though:: it would either be through (un)intentional copycat-engineering for similar-synergy amongst Divinity when Ascending, or it would be based on Raw-Engineering specifics of what happens as a direct result of combining those phenomenon; the first-case scenario would have just been what was natively synthesized when collision was formed though, so perhaps differentiating the two is moot. Concentration would increase Amplitude for bulk Destructive-Force, but surgical Penetration-Power may very well be the sub-souls invested into the substructure but since I have yet to ascend, personally, I have not verified that yet, but ... if the speed increases relative to the subsystem-investments then it would also imply that it would become more dangerous from more advanced Psionic-Phenomenon; as in higher-divinity would emit more dangerous Background-Radiation; which does seem to more/less apply in most cases, but it does not apply in all cases, but then again:: not all higher-divinity by Development-Tier are actually as equally empowered in their Foundations, so it does not need to be a constantly universally observed reality to be an actualization, when in regards to spanning multiple Divine-Soul-streams.
    However, the higher sub-souls in the substructure seems to increase the wavelength, where the increases of local-Tier applications increases the amplitude, so the alterations in speed would not appear to be caused by the native soul-components, unless it is related to the complexity of the immediate Polar-Circuitry that forms each Photon from the Sub-Aspects:{ Resonance & Grab }, which ... may make sense, in regards to how the higher the complexity of the alternating-currents through souls seems to increase the size of the soul-aura, and a larger aura would allow for greater reality-interaction at any one time, and thus greater reality-influence at any one time, but that also causes greater ranges of being influenced by others as well, so it is hard to say whether or not a larger aura would be a positive or a negative to the Influence-Factors whatever they may be, but that would be because it would also directly relate to the Equilibrium-Phenomenon when doing so relative to what it is interacting with at any particular time. With a higher-wavelength with a larger-aura:: it is less likely to be Influenced and more likely to be the one doing the Influencing, but whether or not that has any effect on the Maximum-Speed or the Influence-Factor is something else in particular:: I do not know.
    Relative to the Topic-Conclusion:: I would have to argue, based on the Soul-Science Scientific-Paradigm that I am more familiar with:: the answer is more likely that there is no universal-speed, but I am not sure what causes the speed when it does exist though, but rather:: knowing the speed is not overly important; as it is just a Technology to serve a function, and so long as you can figure out how to harness it as a tool to be harnessed:: knowing 100% of its factors is not important; albeit that is partly just because there are no Universal-Constants when it comes to Physics, so:: it is better to focus on what is relevant to your affairs while merely being aware of other options also existing. Which is the absolute-truth is not relevant because the absolute truth is that displacement does not even exist and time is also an illusion; working within reality is not the same thing as working with actualizations, and working within actualizations is not the same as working within meta-truth.
    It is an interesting topic and I like the video, and it helped me think on some details so more for my own philosophy, further.

    • debblez

      debblez

      Degi Síðan síðan

      How high are you rn

  • FreezeFire

    FreezeFire

    Degi Síðan síðan

    After thinking for a while I am sure the only way to know is being next to a blackhole, where you can shoot light straight and it will travel one direction and reach the back of you head.

  • FreezeFire

    FreezeFire

    Degi Síðan síðan

    Wouldn't we see specific stars in one side of the sky different from the other side of the sky? For really far stars one way we would get star made of mostly hydrogen while on the other side we would get mixed elements stars.