Mars does have its own time zones. Some people working on Nasa rovers have to live in the martian time zone, so over the course of a month the day shifts.
The other guy Veritasium is talking to is SmarterEveryDay. He has a lot of really good videos you can react to but I guess if I may suggest one of my favorites of his called "'How did NASA Steer the Saturn V?- Smarter Every Day 223".
Engineering is his trade. There should be lots of videos where a lot of engineering comments could be made. Did he do anything related to power generation or plumbing? Those would be good fits.
The speed of light does not slow in water or any other medium, it can only travel at the speed of light, when it passes through water the photo gets ping ponged off water particles and just makes the travel distance longer so it takes more time.
I don't like the pingpong ball analogy because it implies that the light can escape the water in any direction, so outgoing light doesn't need to be parallel to incoming light. 3b1b's explanation is much better, so each layer of water kicks back the phase of the light a little bit.
Multiple triangular measurments would make it theoretically possible. Two sides have the light zones, on has the syncro cable. Clocks at the points connected by the syncro and a mirror on the third. Cycling the positions of the setup would allow for a little bit rough, but more acurate number. At least I think that would work, and would give you three relative angles. I do not have the equations needed, nor the equipment.
it would, once again, average out to the same value c. its unintuitive to think about, but its literally impossible to measure cause of the nature of light, the VERY thing we rely on to measure ANYTHING
The guy he was talking to is Destin from Smarter Every Day. He does a lot of science/tech type things. One they demoed a custome see through carberator, others are canons, talks, etc. One kind of significant for me he debunked a claim by Neil Degrasse Tyson that a hilicopter engine fails they fall like a brick, had one of my ralitives say same thing too. I had a chance to go up in one but long line and fear of that I decided not to, found that video but waited too long to go back and event was over then covid came and i regreted it. A few coworkers kept trying to get me to try horse riding but was rather scared of them, I decided i needed to reconsider what i thought about them and try it, wound up loving it and doing lessons going on 4 years evened joined the local horseman club.
Any apparatus can be described by any definition of simultaneity between the light cones, and also by any soeed of light adding up to c over a loop. So if you think you finally synced the clocks you can prove that the physics is identical for another respesentation where they are not, even without considering the physical setup at all, the fact that there is a causally identical respesentation in any convention for c and in any reference fram with respect to the convention means that no physical configuration could do that. What you absolutely need to tell the difference is some piece of physics that simply breaks the lorentz symmetry.
We actually do know at least it cannot be *INSTANT* in any direction because that would mean that the direction it is instant in would not experience red-shift, and I think we would notice if half the sky wasn't red-shifted lol
good call but the speed of light actually has nothing to do with the doppler effect, and our formulas like C=λ×V is already derived from the one way assumption
An important possible implication if the speed of light is different in different directions is when trying to study the early universe with telescopes our calculations of how long ago did what we are observing happen would be wrong; and when our telescopes are facing different directions what we are seeing happened a different amount of time ago when viewing objects of the same distance away.
If light travelled at c/2 in one direction and infinite in the opposite direction, when you're looking at a nuclear reactor in the water, wouldn't you observe Cherenkov radiation only in the direction that light travels at c/2? Because no particles would be capable of traveling faster than light in the infinite direction? In addition, the refractive index of any medium would also depend on the direction the light was traveling through it, which would have measurable optical effects.
correct. Veritasium is fundamentally wrong here. If his postulate held true, the refractive index of vacuum would not be a constant but depend on the direction of travel, and that the refractive index of vacuum can be smaller than 1. This would in turn make travel faster than light possible, which would invalidate pretty much the entire framework of the laws of physics, destroying his further postulate that it'd change nothing about the way physics is understood.
@@Yora21 His hypothesis was that the one way speed of light in vacuum is infinite. Therefore there's no "slowing down" in other mediums in that direction.
for the second one no because your eye sees light after it is reflected off of something similar to the camera idea in the veritasium video. For the first part I'm not sure but my guess would be no or else someone would have raised this question already. There have been thousands of people before us that are way smarter than us and have pondered this, and there are even people now that still think about this. While it's not impossible for one of us to have some idea that no one else has thought about like this I highly doubt it.
@@jwenting The refractive index of a vacuum would still be 1, and the refractive index of any material would still be the same. If you say the speed of light in one direction is c1 and in the other c2, then n=c1(vacuum)/c1(material)=c2(vacuum)/c2(material). Refractive index causes a proportional change, not an absolute one, so the speed of light being different in different directions wouldn't change anything.
Two thoughts: 1. If the speed of light were inconsistent, wouldn’t that make GPS readings incorrect by an amount of distance relative to the satellite’s viewing angle? 2. In order to measure the one-way speed of light, maybe try filling the test chamber with water, but syncing the clocks through a electric pulse in a vacuum. If the amount of extra path the measured light has to go through the water can be calculated, then the one-way speed of light in a vacuum can be found using that
Veritasium is kind of a hack because he is sometimes paid by corporations to put out dishonest propaganda videos that misrepresent the science of a particular subject.
I was wondering why moving the two clocks away from each other wouldn't work, so I'm glad he addressed that. Isn't this something Quantum Computing will be able to solve, since it involves entangled particles though? Entanglement isn't affected by the speed of light, so we should be able to perfectly sync two clocks with it, right?
To my understanding no, though I am certainly not expert, quantum entanglement doesn't allow you to transmit data from one to the other, only to know the state of the other based on one of them. A bit like say you have 2 closed boxes, and a told from someone you know wouldn't lie, that the content of these 2 boxes are the same. You then take one box, move to the other side of the earth, or somewhere where you only can see the one box you took with you. Now you open the box for the first time and find a sweater. You know know that there is a sweater in the box you left behind, even though you never saw it. However putting a t-shirt in the box you have with you, will not mean that will all of a sudden be a t-shirt in the other box, you left behind too. I am sure this is a massive simplification, and again I am no expert, but that is at least my understanding of it
Okay, honest question though: Let's say light were to travel faster in one direction than another, maybe even instantanious. Wouldn't the shape and looks of the observable universe change? Can't we just statistically measure the amount of stars on one patch of the sky and compare them to the amount of stars on another? Wouldn't we expect statistically equal numbers with a constant speed of light or better said: If light were to be going instataneously in one direction, wouldn't we be able to see the edge of the universe that way?
well, i suppose that the assymetry between matter and antimatter is caused by the fact that neutrons don't annihilate that much since they're neutral and then those decay into protons, electrons and antineutrinos
The instantaneous version however also has the consequences from cosmology that you should see the cmb only from one direction and infinitely far in the other direction and to restore the symmetry you should be moving away from the direction you get infinformation from at c, bringing us right back to the scenario where earth sees mars andnmars sees earth at the same "age" so to speak. This is a good argument for why it can't be instantaneous in one direction, but that argument doesn't bit for local directionality of the speed of light, that would correspond to a foliated background and motion with respect to it, it turns out that when you allow this background to flow then the flows and equivalently the speeds at which stuff is moving with respect to the "medium" can only be the ones you get from the prediction of general relativity, which is amazing.
They way you would do it is to give up, but the best try for sycing the clocks is to have the clock be adjusted by an accelerometer on board and its clock tics along the way. The problem is ofc that the physics you are using for all these tests are themselves lorentz symmetric and so you will never win.
No twisting the metric not embedding in higher minesions, all it requires is a topologically identical space, think about for exaple what would happen to a rope if all its atoms got smaller, or even just lenght contracted innthe direction of the rope, when the end points are at a fixed distans, ofc the tension would build until in broke, if the sizes of atoms change directionally and that change changes in space, then the path at which a rope would be stretched across somenpiece of space would not be the shortest path for the rope, evem if it is the geodesic in the euclidian geometric sense, the geodesics would be different for the embedding space andnthe intrinsic space, even when they are the same space and there are no extra dimensions to be found anywhere.
The biggest thing is that every calculation will be always diferent, or should we say wrong. That is the problem with not only this but everything and that is why, for sake of simplicity and easier calculations, everyone is using constants in/for "perfect case" scenarios for given asumptions. What if the diference between clocks is exact (or the time) but the diference ocurs due to the one particle/molecule of the clocls equipment (from electric side of physics)? Nothing will be meassured or calculated precisely because of way tto many variations involved. This only shows that nothing is perfect yet everything/everyone is unique and perfect in their own way and it works just fine and as intended. Science overall is just one huge what if world we found ouselves in and that is pushing us forward in new explorations, adventures, etc. And for me this is the biggest charm and beauty of our lives, our world and our universe.
The CMB and distant stars are the answer to this. He's technically right that we can't measure the speed of light in one direction, but we can verify that it is the same in both directions because expansion causes redshift. You could try to balance out redshift by integrating the speed of light into expansion rate, but that would skew parallax. You can't adjust both expansion and parallax to make the speed of light different in different directions. Granted, that's to within the limits of current measurement, but those limits make the range of difference trivially small.
Well how do you know two galaxies are of equal distance to us? If we observe two galaxies that appear to be redshifted to the same degree, we assume they are both the same distance because we assume the rate at which the objects are moving away from us due to the space between us expanding would be the same. However, if light traveled faster in one direction, the same redshift from both galaxies could be achieved from one being closer to us than the other. The light traveling from the farther galaxy would still reach us at the same time as the closer one, so the redshift effect would be the same.
@@Anonymous4045 The "equal" part is irrelevant. You don't need the distance or redshift to be the same in both directions. Two non-equal distant objects with different redshifts are just a math problem. The point is that you need a factor that allows reshift to change with the speed of causality (ie. do the math to show what you assumed). But you also need to account for parallax - how distant objects appear to move relative to one another based on your change in position. And while you can explain one by linking the speed of causality to it, doing so to one skews the other.
The possibility of instantaneous return trip sounds interesting 🤔 Chat GPT sure likes to go off on this topic. Try ask it some questions on the topic perhaps. I was trying to inquire with GPT if deja vu could somehow be the result of instantaneous information transfer and if it could be used similar to the cog mountain experiment to measure distance to the causing event. While ridiculous, GPT has an interesting ability to explore such topics. Anyway, nice videos!
Then, when we look to the sky we would see stars just as they are in that instant on one direction and billions of years old on the other direction and we wouldn't be able to tell the difference? I don't buy it.
@@martinstubs6203 It's not a question of me buying it. It's just that when we look everywhere in the universe we see stars with the exact same age relative to us. To think that light speed has a directionally specifically to the planet earth is the same as believing in héliocentrism before we had evidence of the contrary. Yes it can be true, but you would be claiming that we are special to the universe somehow.
we see this in light frequency, red and blue shift, but its the same in every direction, we can use light to measure the distance to the moon, close enough to calculate from earth, how much fuel we would need, yes we mesured it.using lazars and radio sygnals.all matches up.
Could we use our astronomical measurements, such as by the JWST (webb telescope), and theorized knowledge about when could the first black holes or solar systems exist, etc. And look in opposite ways away from our solar system and look for evidence which side looks "younger" or "older"?
Could you rely on the momentum of a photon? (they do have a momentum, right?). If I know the mass of a ball, I throw it on something that measures the energy in the impact I would know its speed, at the time of the impact. That's different from the methods for measuring speed proposed by Veritasium because it would be a "one way" measurement. (Anyway, please be kind, I know nothing about physics, I am just a dumb finance guy...)
Hold on... you're a science RU-vidr and don't know Destin from SmarterEveryDay? haha! He's WONDERFUL. Makes so many very fun and very cool videos, but also seems like a genuinely great guy. Highly recommend literally any video he's made. :)
It feels like, at least for the extreme examples like c/2 and infinity, that there would be obvious differences in the apparent structure of the universe if this were true. Like if c was infinity when coming from some part of the sky, we ought to be able to see things that are infinitely far away in that direction, but in the other we'd only see half as far as expected. Unless I'm missing something this should constrain the effect of this asymmetry, if it were real, to something that still allows the universe to look roughly the same in all directions.
it should be kinda possible, all we need is another object traveling though vacuum at known speed. speed up a rocket to 30km/h (or any other object that we can speed up to very precise speed) in space. set up a clock at both ends, start light right as object passes start point. do the same at end point, start timer as light arrives. difference between those speeds is speed of light, subtracting speed of the other object. and its one directional. repeat backwards for other direction. Not that hard to set up in space, all you need is like 6 objects with known distance away in space.
Curiosity, would this suffer the same problem if you set a top of the line slow motion camera on the ground pointing up and, at a predetermined hight way above, used a laser from one side then the other side and see how far it travels in one frame, if this could work would it need to be done in space to prevent atmosphere from interfering with results?
Point light source at super high speed camera at a specified distance. Turn camera on. Time how long it takes the light to reach the camera. I'm average now Joe and have no idea if that would work, but that's my idea.
13:34 for the middle clock synchronizing the two other clocks, instead of sending out simultaneous electric pulses that travel at the speed of light to sync up the other two clocks, can't you use something else that doesn't travel at the speed of light to sync up the two clocks so that these two clocks are actually in sync? Therefore making measuring the one way speed of light possible?
Oh there are many solutions, but this is just a philosophical type of question rather than scientific. Veritasium may be correct in the fact that we haven't measured it without bouncing it off, but you could just replicate the experiment, which I'm sure has already happened before, with the light pointing at different ways, so the question should be if light is faster when reflected, but that's easily disproven, so you have to go for a philosophical pondering rather than using actual science to define it.
@@selascothe information of the rope being tugged would travel at the speed of light. If you have a light year long rope and tug on it, it would take 1 year for that affect to be felt at the other end of the rope
The thing that is traveling experiences time dilation or length contraction depending on the frame of reference you're looking at. This length contraction depends on the speed of light.
I said it in original video and I say it here- at least huge difference is not possible, because we would see a huge difference in astronomy. Like with cosmic microwave background- looking in one direction you would see completely different image than looking in opposite direction. You would get completely different age of universe looking in those directions, CMB would not be redshifted in one direction (or at least you would see a big difference in redshift).
I guess the point is, that it doesn't really matter. Because we can't tell the difference, even if it there is a difference, it all looks and works the same.
if Veritasium makes the assumption that the speed of light in vacuum is not a constant (which he effectively claims), he also has to assume that the index of refraction of vacuum is not constant, but depends on the direction you're measuring it in. Which just makes no sense whatsoever. c = nv, after all. And by definition n is always >= 1, as v must always be smaller than c unless we postulate that the travel faster than light is possible. Veritasium is wrong here. He's especially wrong in his assertion that a variable speed of light in vacuum would not change the basic rules of the universe. It would change everything we know! And yes, I do have a degree in physics :) Consider this too: If the speed of light depended on the direction of travel, a beam of light from Mars to earth would take 20 minutes and the return trip 0 minutes BUT a beam of light from earth to Mars would take 20 minutes and the return trip 0 minutes. Now explain that.
After you said that with the timezone I thought about what if the speed of light depends on the zone you are in. Or if c depends on the direction of light if it is in the direction of one of those zones. If we truly can not measure it we can be very played be the laws of physics xD.
I wonder if we could use the starlink laser communication to conduct an experiment like this to measure one-way speed of light. @Spacex might want to look into that
C is a variable in other equations, like E =mc^2. Can we ever measure the difference in mass before and after fission/fusion elements, along with total energy produced, then derive C?
Logically speaking the best way to compare the speed of light isn't a direct measurement. Rather it is to compare the age of stars at say 10 billion light years away and their spectral composition. If light is equal or nearly equal in all directions then the relative average spectral composition will be the same. However if there is a significant and drastic difference between spectral composition you can in theory use that to roughly estimate the difference in the Vector Velocity Limits of C based on the relative difference in stellar age. This should in theory work because the early expansion of the universe was super luminal (there by short circuiting the relativity problem of moving objects to measure C) and stellar bodies should have the same relative ages in all directions if the vector velocity of C is equal in all directions.
I think it's the same in all directions. There are other phenomena which use the speed of light as a proportion, such as E=mc^2. If the speed of light changed based on direction, the output of nuclear reactors world change based on time of year, and time of day.
The only way I thought it would be possible (in theory) is by shooting a clock at the speed of light. Basically, the clock makes the trip. Once shot, the clock starts instantly. Once received, the clock stops. But this also depends on our perception of time, and that matter can withstand traveling at the speed of light, which so far we think is impossible.... This is giving me a headache 💀
What's the problem with this experiment: At 11:04 it shows that moving train. Just do that and measure where the light hits the mirror. It will give you an absolute position from which you can calculate the angle. Then let the train move in different directions. You probably could do that on the ISS instead on a train because it moves way faster and therefore probably shows more difference.
If light in one direction would go faster then in the other direction like where Veritasum tell one way you see it with delay and the other direction its instant. If that would be the case wouldnt that mean that galaxies and stars in one direction would look different then galaxies and stars towards the other direction? Then you would have red shift in one direction and no red shift in the other. Since that is not the case (As far as i know) i would say light goes in both direction at the same speed.
What if you connected two clocks with string, start them at the same location, then move them in opposite directions at the same speed, stop the clocks when the string is tight and compare time dilation
What I find amazing is that you can picture time dilation as an car driving on a highway. The faster the car moves, the more air resistance it faces. In a similar way, the faster an object moves through the universe, the more time dilation affects the clock of that object. If God would have a clock for every atom in the universe, every time an atom would change its speed, the speed with which its clock moves its gears would change as well.
The reason it is confusing is because we think of speed in terms of "0", IE the speed at rest with respect to a reference. For example, standing still on the surface of earth is "0" of whatever speed unit you want. But the reality is that there is no "0" point, from every other reference point it doesn't work. Light is the convergence point, its speed is the same in all contexts. And since there is no "0" point, it messes with our understanding, because the convergence point has energy, unlike 0 mass or 0 electric force. It's not a speed limit per-se, it's a reference point at which all other reference points of a lower relative speed could be evaluated equally, if our math and understanding was good enough. An experiment that would work is if you fired a beam and then split it to either side of a black hole to enter an orbit, and have the light orbit one time before returning. Then have two sensors at a distance the same diameter as the hole, so that the return beams are parallel, synchronized by shooting two beams, then doing the same but shooting the splitter at the opposite sides of the hole the second time (right to left and left to right). The beams should arrive at the same time back on the sensors either way, but if there is any drift we'd see it because there is exactly one beam going "left" and one "right" around the gravity well, while the return paths cancel each other out. Good luck doing that tho lol, and it doesn't rule out a universal gravitional "direction" for faster light. Also, light doesn't go "slower" in mediums other than a vacuum. The reason it appears so is due to the constructive and destructive interference from the matter in the substance interacting with the light. Feynman's lectures on QED show this plainly and intuitively.
Well, all i understood that even if speed of light is assumptious total time difference between two points is constant no matter how much faster message travels one way than the other (but its still important to measure real thing to use it to our advantage). Time is distance. Also not sure but experiment with highspeed camera measuring speed of light will still be valid even if all the camera captures is reflected ligth, no?. Also to synch clocks we can use quantum pairs, i heard we (i mean i remember only about Chinese scientists but by 'we' i refer to humanity) had some experiments with helium(?) creating those (pairs)?
From our perspective as a stationary observer in the foliation, the light traveling at half c in their frame never reaches mars, because from our perspective mars and earth are pancakes traveling at c arbitrarily close tl each other to male the distance in their point of view finite. You see the infinite case is absurdly unphysical, but any finite versiom works fine ^^ the trouble with the infinite version comes from the lenght contraction and time dilation being singular for motion at c relative to the background, and infact every possible choice of background that isn't this infinitely thic cone of everything moving at c, which can be defined for itself but then everything traveling at a slower speed has the analogous problem for them. This stuff is amazing isn't it :-)
The key to starting out at an elementary level is to start with a difinition of mass and inetria, just take a a little box of light as a test mass, and then make the box hanve tension such that if the light slows down the box contracts, then you look at the conformally symmetric side of lightcones and contractions and stretching of the lightcones, and let the medium flow like a fluid and consider moving lightcones as equivalent to tilted lightcones. If you start with simple examples and you cinsider the number of bounces of the photons inside the box as a kind of clock defining intrinsic time you are good to go. If you decrease the speed of light in empty space in a single direction linear and such that the derrivative is a constant in space you get to 0 at some point and then the rest of the space is just a uniform gravitational field with no curvature conformally speaking, when you introduce the mass it will change scale and times depending on where it is and you have a curved space in its simplest case, equivalent to a sort of gravitational capacitor plate, because of the curvature of the space being uniform a single mass will not see any curvature so to speak. If you build something in the space or move you will find curvature but the mass doesn't know without some other reference object, because when you go one meter up in the field one meter to the right, one meter down and then one meter down you dont return to the same point, but it isn't knowable without some other references mass that stayed where you where for example. It is fun, give it a try, gravity is always relawto the derrivatives ^^
In the future can you make one new comment, and then reply to that comment with the follow up information. At the moment you have made 15+ individual comments that are all over the place and it is very difficult to follow them, once this video gains more comments then someone may have to spend an hour just finding all of your comments hidden with everyone elses. Even if you did find them all, they will be out of order. For you, your comments may appear near the top and are all joined together, but for everyone else they are hidden among hundreds of other comments. For the average viewer this is just too much work. Even for the uploader of the video who can filter out comments and just find your submissions, the comments will still be out of order.
So, I think that the speed of light is constant in both directions for a simple reason; instantaneous speed means infinite speed, as instantaneous would apply over an indefinite distance, and thus it would also mean infinite energy, which should not be possible. Specifically, the light would need to travel at the speed of infinity at the acceleration rate of infinity, as it needs to reach the speed of infinity in a theoretically infinitely small and infinitely large distance at the same time, which would make a black hole's ability to capture light impossible, as it would need to be able to exert a gravitational pull with a force greater than infinity in the direction in which light travels instantaneously, which is simply impossible as greater or less than infinity is still infinity. Furthermore, assuming that a singularity could, in fact, produce a gravitational field with the properties needed to capture and contain this infinitely fast light with infinitely growing infinite momentum, it would also drastically change the physical structure of the universe as anything in the direction in which the singularity exerts infinite gravitation pull would end up being pulled into said singularity, as infinite gravitational pull would exert itself as an infinite acceleration rate towards the singularity over an infinite distance.
Btw, as it is impossible to disprove the instantaneous light theory, it is still better to accept that the speed of light in a vacuum is universally constant.
could you not look to space to figure out if light is faster or slower in certain directions? because if light traveled faster in a certain direction you could see more distant stars in that directions
It's not just an academic curiosity. If we were to somehow answer this question and empirically determine that there _is_ a preferred direction of light, that might open the door to radically new physics.
It is possible to formulating relativity with an asymmetry in the speed of light, the equations just get more complicated. Just take normal special relativity in a single reference frame, with time dilation and lenght co traction for moving things. Then you simply apply the Galilean transform to the coordinate system and equations of motion :). After calculating what that looks lile you will see a picture where the speed of light is not the same in all directions, but always the same over a loop, this problem was the original motivation for lorentz for accounting for the Michaelson Morley experiment. You can easily see that doing what i just described leaves causality preserved, we are still viewing the same theory, the same physics if you will ^^ all we did is apply coordinate transformations to a foliated version of special relativity. The case of infinite speeds of light in one direction is not so easy to see, it seems like you need to put in an infinite velocity for the galiean transformation of the coordinates, but this isn't the case, if we start with this background and we then apply a galiean transformation and motion of the earth and mars such that what we put in, the earth, mars and so on are all travelling at c in the opposite direction from the desired direction we want c to be infinite, we get infinite lengt contraction and infinite time dilation, if we then look at what the earth and mars should see in their coordinates so to speak it turns out that from their perspective signals should travel infinitely fast in the direction opposite to their motion through the background. If you are observant you would also see that the distance between them in that boosted state is infinite according to them, but that is a detail, the case of infinite speed is not physical so to speak it is an irrelevancy because boosting to c relative to the background takes an infinite amount of energy and momentum anyway. But i hope you get the picture, for finite differences it doesn't look as strange :)
You should look at the Kyle hill video the worst software error. About the theriac machine malfunction and eradiating people with lethal doeses instead of treating the cancer.
quantum entanglement is real….. could we not synchronize the clocks using quantum entanglement? another thing is , i assume that quantum entanglement also transfers information at light speed otherwise that would mean that we have a method of communication faster than light speed. So could we not just get 2 clocks that are quantum entanglemed to eachother and their time difference on stopping/starting would be the time that it takes for the information to transmit using “quantum entanglement” which i assume is C due to my previous point.
I think if the speed of light was different then you'd see older universe looking one direction than the opposite one, so the universe would not look uniform.
well, so far we have goten along just fine not thinking light tricks us, and speeds up when our back is turned, but if you want to start taking this consept into acount, how big is the solar system with this in mind, or dose it just afect things we cant observe or test? is this just a thought experiment, if so, get back to me when you have some numbers, and explanations.
two ways of disproving veritasium, ask the people while on the moon about the communication delay or get a really really high speed camera like some of the 1 billion fps and 70 trillion fps experimental cameras that we have to measure the speed of light in one direction.
I think speed of light depends on the atomic mass and space pressure (of its traveling space), the bigger of either = the slower the light, and the opposite, light never travels in a single direction it always waves, depends on how it waves in that space where it travels. Just like people we move slower through water than we do through air, but in both cases we must move our body to travel, move by move. If the space was 100% vacuum and the clocks were 100% synced then it would travel with the same speed in both directions, but in reality I think it never travels at the same speed, some materials absorb light, some repell it and some ignore it, and some even emit their own, so in its terms the original light does not have infinite path, it transforms by constructive or destructive interference. To measure only one direction of travel for light seems kinda pointless to me, because we are always one of many observers, it must return back unless we're observing a black hole, then it makes sense to measure only one way but still pointless. Besides that, we know "2c" which is enough if we need just "c", and there are more factors for a very very very small speed offsets in which I don't know why those very small offsets would matter due to its extremely high speed.
Best answer, spread the light in all directions and view from above. If we see it get there sooner one side than the other, we would know. Impossible to get wrong.with double 2 way, the 1 way is still able to be accurately derived. And also the sensors at each point would clearly show as they did with the bottle that moving through and objects we see the change in light paths. The same bad logic says we can’t see where an object is going if we look at where it is. Yes we can. Echos and 2 locations are needed for speed anyway and trajectory
The other thing that I know full well that people have been able to document is something called ping. Computers have to send signals and the delay is similar in relative to how light works because we're sending signals satellites which are sending signals back. Also Electronics move similar to a speed of light. Multiple sensors make it easy to measure the general local speed of light and if that's similar measurement is enough that it is seen everywhere with similar conditions or variable conditions and then you calculate what happened to it in those other situations then you still understand what's happening to light and the concept of it moving instantaneously in any direction is thrown out the window entirely because no one's going to assume a Time Warp what is that massively effective. That crazy assumption needs extreme proof. The micro changes in the possible times can always be adjusted for. We would need to be near a black hole to start noticing issues with light. It's the lack of scientific rigor and proper scientific method that makes this veritasium video actually disgusting to me. Semi curious but not enough to uproot the entire functions of the world. Ask special case questions in reference of special case scenarios not in general case scenarios where we already have a completed understanding
@@cliptracer8980you can't do that because your timing is still based on the assumption that it's equal. The video literally directly went through your example.
OK, so you can't prove the one way but you could disprove the different direction speed of light variance pretty easily, sync up 4 clocks, send them off in 4 directions at the same speed from the central point, ignite a light and have the 4 clocks measure, if they detect the light all with the same time offset then it's constant in the medium it's in, if it varies then you prove a variable speed of light potentially based off direction.
Sorry for a 3 page essay ^^ but the sunject is fun, i actually told Derek about this one in a comment, and he made a video about it, and no wonder, these things are amazing, and not intuetive, nature is a genius without equal.
The core problem is that the speed of light isn't about light. It's about information. You can't get information from A to B any faster than c. Light, having no mass, in accordance with E=mc², is in effect, "pure information" because it is pure energy. Note it also isn't a "limit"... it's described as *the* speed. It not only goes "the speed of light", it *has* to. This applies to all electromagnetic radiation, which would be the only way to measure and communicate data about it. Since nothing can exceed this, there's no way to get information from an experiment itself to provide a frame of reference. Without a reference, you potentially have the situation described in the video. It could be doing all kinds of weird things, we can only interpret based on what we are capable of observing. We see the average, if it isn't the same in every direction, and call it "c", because we can't tell the difference. Personally I don't buy the instantaneous (or even just assymetry) but there is merit to the argument... We don't actually *know* and never can, because there's no way to make that happen.
I thought light speed is constant and spacetime is the variable that changes how we measure the constant, but I don't really know. I've only recently settled on the notion of gravity being an effect and not a force. the nature of time still escapes me. the nature of distance is strange to me as well, because there is more than one way for information to go from one point to another and sometimes time isn't a factor when it seems it should be. this is irritating I don't want to keep thinking about this.
If you want to be a big boy and understand the emergence of gravity this point of view is thw most useful one, because the energy momentum tensor gives you forces and not geodesic motion, so you can extend relativity to superluminal physics without making it extremely tedious to use conventional geometric languages. In this language infact the geodesics are not geodesics of space but light bends because of the Scalar speed of light changing and space flowing(which is the same as tilting lightcones) it is not a force, but an effect of the derrivatives of the speed of light and the flow of space. This fixes a lot of the problems with gr for uniting it with quantum mechanical phenomenon. And we already have a suggestive mechanism for the change in characteristic scale of matters, physical lenght contraction for directional and hawking evaporation, hawking evaporation for masses as tiny as particles would be huge and short lived, pop and no more electron, but this sounds familiar i thought one day, this is just like the hydrogen atom, it should also go pop and disappear, and some days lated i figured out how to make the tiny radiating mass non go pop and stick around, one of the effects is that when such a tiny mass gets very close to another mass it shrinks, because the interaction between the two masses and the vacuum is such that the equilibrium with the vacuum and the hawling radiation is altered, yielding a different characteristic scale, but also a different local speed of light, which is also slower, the combination yield a characteristic scale for time and space near masses in am intrinsic sense and that is how to build a universe.
And what i said about general relativity is true, but to get general relatively you also need a scalar speed of light to change, but this scalar change in the speed of light os also unobservable, physics is invariant to a change of speed of light except for the time it takes fornstuff to happen. Just imagine a change in the scalar speed of light as taking a lightcone and stretching or squishing in innthe time direction, making it steeper or more shallow, and changing the directional speed of light as tilting it and squishing and stretching it in the time or spatial direction to adjust the scalar. If you stretch and squish or tilt in the same way across all of soace and time so the derrivatives of the stretching andnsquishing are zero then you habe not changed causality, if you tilt, stretch and squish in different ways for different places then you have a non zero derrivative and that has physical effects, namely the effects of general relativity.
When verit... whatevers video came out i damn near lost my mind on them. If the speed of light was immeasurable then we wouldnt be able to communicate with things like spacecraft and know what kind of delay to expect at a given distance. And their fan boys gave me no end of "you dont know what your talking about ". As a lowly mechanical engineer im glad somebody higher on that food chain decided to explain how stupid this idea is.
A day on Mars is very similar to Earth, but still 37 minutes longer. So no matter what time zone on Earth you choose to set your clock to on Mars, sunrise will be 37 minutes earlier every day. For the computers on Mars probes it doesn't matter. The probes don't care if the sun is up or not to run their systems. But people on Mars would have to have clocks with 24 hours 37 minutes per day to keep a day and night rythm.
I believe that the speed of light is ever so slightly different in each direction, as we are flying thought space at unimaginable speeds. I it is like shining a flashlight in a train car moving at near lightspeed. For our frame of reference however this difference in lightspeed is negligible, because our velocity through cosmos and everything is just a tiny fraction of lightspeed. I do believe that we did calculate the speed of light fairly accurately and any directional effects wouldn't affect the accuracy. You could also perform the test in multiple 3D orientations and compare.
There is a video on RU-vid where a high speed camera traces the path of light travelling through a medium. There is the third detector watching the emission and tracing the path of the light to the destination. This negates the problem of knowing the speed of light leaving you and not knowing it’s return velocity. Light travels the same speed in all directions. Also, relying on laws of physics, if the light returned instantly that would mean the return beam would be infinitely blue shifted requiring infinite energy. Conclusion: the veritasium is indeed clickbait relying on dubious illogic to make a fake case. Upside: he made money out of that video. Congratulations again youtube.
It's entirely an academic yerkoff. When you spend at least 3 minutes studying astrophysics you'll know that the earth doesn't actually have a nearly perfectly circular orbit around sol: It's a bit more like a helical orbit as sol orbits the Milky Way. If the speed of light had a directional preference then the universe would have flashed its bitties at us periodiucally.
Just measure the time it takes for a star to disappear when a planet passes in front of it. We know the orbits and can calculate C from multiple directions. *someone has already done this experiment and discovered light has a speed.
No when you habe light traveling in some dielectric medium ina convention lile this, as you can see for my argument, works the same way only it happens at a different speed in different directions. You basically to the same calculation to see the slowing down of most of the light in the stationary frame like normal, but then the rest is just coordinate manipulations, which isn't really a physical change so to speak :). What you should do is understand the phenomenon with respect to the stationary frame, and then see what it looks like in a different frame. When you go back to standard relativity it works the same, the physics ks identical between different frames, but when you perform a lorentz transformation certain phenomenon look like they have slightly different explaination in terms of out intuitions like charge densities vs magnetic field due to length contraction in different directions and so on. But if you think really hard about it, you realise that both transformations, the Galilean picture for foliations and lorentz transformations in more of a standard way are always only transformations of a picture of the same causality, points that are connected in one point of view are connected in all points of view, the øightcome structure doesn't change in either way of thinking about relativistic physics, only the equations after applying a coordinate transform changes. When you are talking about the ambiguity in what has changed in standard special relativity for example from one pointnof view at a given time and location a proton and an electron in a wire can be almost touching, but from some guy driving a fast car right next to you they can be far apart without anything about causality changing, but that is because you are not at the same location as those two particles and if you and the guy with the fast car were there when the two particles met you would agree when they met even when you argue about simultaneity, the two particles meeting up is a special unchanged moment for all observers, it is just that when that unchanged bit happened is being argued about. So what interacts with what when is never in question, and so even if the world looks to be doing different things at the moment depending on your point of view, everyone always agrees on everything that ever happens and every location of everything for all of time andnspace, the coordinate transformations are entierly unphysical, it is just that the order of when a certain particle was there with respect to some event here looks different from different points of view, but that doesn't habe any causal implications. Even phd or nobel prize winners get this wrong sometimes. And it is the origin of why people are confused about superluminal motion for example and time travel, because just learning how to use special or general relativity doesn't save you from mistaking playing around with coordinates from physical effects, what happens where and when, like all the trajectories a soesific trajectory intersects is not something that has aky coordinate dependence, the interactions can only be changed to the same thing during a coordinate transformation because they are infact ofc the same point in spacetime, so whether or not something is moving has nothing to do with what time you can move to if you could teleport of jump to a speed faster than light, once you introduce that you have a choice of allowing travel into the past in the past lightcone or not, and allowing if for all reference frames at all time and locations simply means you allow for time travel as a phhsical possibility, if you disallow time travel as a possibility then you either say everthing traveling backwards with respect to one foliation is actually something like anti particles traveling forward, or you have to say that only one foliation or reference fram gives the right boundry for what instantaneous travel is like, aka you have to be more clear about simultaneity means, when you are talking about superluminal travel. When you have no superluminal travel, you don't get any consequences from assuming all the notions of simultaneity are simultaneously true, and you don't for superluminal travel either, but if you assume all the trajectories that can be considered forward in time from some perspective can be travelled then yoj are assuming the whole space like region outside the øightcone is traversible and not only half of it. The difference between time travel being possible or not possible is this question of whether you can populate half the cone with trajectories away from the origin or the whole, this is a physical question not a coordinate question. The difference is whether or not a certain trajectory can be populated, which is coordinate independent as a statement, if you assume that only one definition of simultaneity is true, and you define sub instantaneous trajectories given that, then independently of which definition you start with it is still impossible to get into your own past lightcone given you have the ability to travel anywhere you want instantaneously. A version of this argument is as robust in general relativity, and hasn't been recognised as such in any very clear way. Which is why some people say things like " well if you could travel faster than light, you have worry about killing your grandpa and so on, therefore superluminal travel could never be possible" but that is just wrong to say, because half (in a technical sense, meanig half the span of the angle when the instantinaety cone is symmetric) the trajectories are perfectly fine at a time, meaning according to a single definition of simultaneity, no matter which you can travel instantly anywhere without breaking causality. Just a fun tangent, but i think it is wise for us to slow down a bit and learn the basics really well as a scientific community, when these theories where first discovered, the community was in an age of absurdity and discovery, where suddenly everything seemed to be flipping on its head, and i think the basic ideas of 1870-1915 never really got worked out in a basic way such that is possible to understand what you are talking about. Most people i observe talk about these subjects in kind of an incoherent way, where the lessons are sharp and easy mathematical models adjoined to no quite sensible statements about them, and then they move on to øore advanced stuff, ofc because the mathematics is actually precise in the domain it is applied, it doesn't really muck up the more advanced consequences for other subjects, but now when we go to blend together gr and qm, or try ti tackle dark energy and early time cosmology and so on, thennit really pays off to understand the basics in all the possible ways it can be looked at, in my humble opinion ^^. You can know how to derive all the consequences of special relativity and have no idea what so ever of the iceberg of nuance and wonderful perspectives that lurk beneath the surface level of conventions.
Wouldn't light from distant stars correct for this, at least to some degree? If the same distance observed in different directions has a similar composition of stars, but different distances have different compositions, then light is at least taking a similar amount of time to travel in any direction. You wouldn't be able to say it's the exact same in every direction, but you would be able to narrow down the range of possibilities. Unless a different speed of light also messes with those distance calculations enough to make it indistinguishable again.
tl;dr: C isn't defined via measurement of light waves, it's defined by universal constants. His examples don't give any reason why light should be different in different directions, and they constantly mention "round trip" speeds when referring to single direction light waves, or different waves; he also ignores the effects of changing directions between objects. Other physicists I've spoken to don't have a very high opinion of Veritassium; sometimes he doesn't seem to really understand the topics he's talking about. I'm pausing this video early, so I might need to edit this later, but for what it's worth, we covered the synchronization of clocks to measure light in one of my early undergraduate physics classes. In the higher level classes we derive C from some Electromagnetic principles, and show that it is defined by 2 universal constants. This means that we don't "measure" the speed of light to determine C. I'll avoid being mean, and simply say I'm not a fan of many of the things Veritassium says; when I still worked at a university I spoke with physicists there, and they had the same sentiment. One of the core tenants of physics is that the same phenomena and "rules" should occur without a dependence on location. If you're in North America, and you drop an apple, it will fall to the ground; this will happen (and be governed by the same principles) if you drop the apple in Australia or China. Now, let's say you drop an apple, it falls to the ground, then you pick the apple back up, take 2 steps left and drop it again. If the apple flies into the sky instead of falling, we would start by trying to see what else in the environment is different (maybe you were holding it over a strong air stream) before saying "Welp, guess our idea of gravity is wrong". So to assume things are different purely for the sake of wanting things to be different is a bit asinine. He's also not being consistent with his "light is faster in 'this' direction. For example, he says "Mark on Mars receives a one way signal", then he talks about the "round trip", but it is a different light wave, and it contains different information (light isn't bouncing off a mirror on Mars and coming back). So the "round trip being different" doesn't apply, and similarly, the distance and "direction" between Mars and Earth will change with time, so Earth won't always be in the "instantaneous light speed direction".
"So to assume things are different purely for the sake of wanting things to be different is a bit asinine" I think you're missing the point. He isn't assuming anything, he is pointing out that *you* are the one that is making the assumption that its the same in all directions, when you can't really prove that.
if the speed of light was instantaneous in one direction, wouldnt we see a bunch of very old galaxies way further than we should be able to to one side of earth?
BUT all bodies are in high speed motion through space all the time. If there is a direction-dependent speed of light it should show up through repeated 2-way measurement anomalies, as every time the experiment is repeated, the entire experiment has spun farther around the sun, which is rotating through the Milky Way, which is moving through the universe and so forth. It's not a mathematical certainty, but doesn't make sense that direction-dependent light speed would be somehow relative to Earth, or position in our solar system. My two cents...
So what if you have a (1), (2) and (3)clock all starting at 0 then you start (clock 3) send a light let’s say (light 1) from (clock 3) through (clock 1) starting the first clock and then have it go and hit (clock 2) starting the second clock; which sends another (light 1) back to (clock 1) stopping (clock 1) which then sends another (light 1) back to (clock 2) stopping (clock 2), then you can look at all clocks. Note the light used for both trips must be the same wavelength of light or the reading will be wrong for just the speed of (light 1) And the clock set up would be like: (Clock 3)-(Clock 1)---->(Clock 2) (Clock 3) (Clock 1)(Clock 2) Stopping (Clock 3) and (Clock 2) at the same time. In the end (light 1) will have traveled one direction two times and the other direction once so you can then see the difference between the directions.
So I just thought a better way of checking if we are right about light speed. So if we know what the round trip of light is then divide that number by 2 then set a delay from (Clock 1) to (Clock 3) telling it to stop if (Clock 3) and (Clock 2) stop at the same time then we know we are right but if there is a difference between the two then we know we were wrong.
The problem with Veritassium’s claims is that there are ways to measure the speed of light other than “time of flight” experiments. You can also measure speed as wavelength*frequency. You can examine this in the context of microwaves, which operate based on standing waves. Standing waves are composed of two waves traveling at the same speeds in opposite directions. Basically if the speed of light were anisotropic, microwaves wouldn’t work.
@@martinstubs6203 The claim “It is impossible to measure the one way speed of light” is incomplete. All of the suggested methods, including the ones SED gave were “time of flight” experiments, where you have light travel some distance, then see how long it takes. The synchronization conventions don’t really deal with light as a wave and electromagnetic boundary conditions.
Calibrate the 2 clocks using a practically infinite number of entangled particles. Set the far clock to 12:00 but don't have the timer on it start, when time starts approaching 12:00 have it check the entangled particles once every Planck second. As soon as the first clock hits 12:00 have it observe all entangled particles, as soon as the far clock detects this has happened have it start the timer. Assuming both the clocks are properly timed they'll be calibrated to each other within one Planck second and will be able to accurately measure the speed of light one way to within one Planck distance of potential error over the entire test duration. Practical? Absolutely not. Possible? Most likely not. Definitive? Yes.
Not all the way through but couldn't you hypothetically use a radio signal with a known time delay and also a known electrical delay for the light to trigger and have a light shown back at you from far away and subtract the known times. Edit: also just a really long electrical wire would likely work since I'm sure people have a number for the speed of that.
The guys on earth send messages to Mark to wave 👋 and if he waved at the same moment we will know the speed if he delayed we will count the delay then we will know the speed 😂😂
you can simply send out another signal with a known speed at the same time as the light pulse, then the detector end can use this information to calculate when the light pulse was fired using the known speed of the second signal over the known distance both signals had to travel. there is no need for synchronized clocks, in fact the start of the signal doesn't even need a clock for this to work.
