Physicist Carlo Rovelli has a nice short book called "Order of Time" where he explains this quite vividly. Basically "now" is only applicable to "here" and we intuitively extend it to things around, and that kind of works while discrepancies remain too small to notice. But on a larger scale "now" doesn't mean what we're used to, it loses its meaning. All the region of spacetime outside our past and future light cones is "extended present" with no fixed order "before or after or now" relative to us, and it's not directly observable anyway. He offers some casual metaphors from real life to get accustomed to such thinking.
@@Mahesh_Shenoy How do you know that we don't see Andromeda galaxy as it is right now? Relativity of simultaneity means you cannot agree on what is right now outside your reference frame therefore you cannot claim that light takes time to travel towards you because that is only under the assumption that light travel at speed of light in every direction. The truth is two way speed of light is constant but the light could travel one way at any speed between c/2 and infinity.
@@classicalmechanic8914that's why Einstein already mentioned in his original 1905 paper about light Speed. He said that "all the theory is made under the speculation about TWO WAY LIGHT SPEED is 'c'. We never know one way light speed. So one way light speed can be even infinite, but there is no way to test it. So we kind of belive it that it is c/2. Because we can't even test it or prove it nor disprove it.
And nobody knows what the spacelike 'extended present' outside of our light cone means. It is interesting, as this is where inflation and all cosmic theories come in, considering the cosmic background radiation is within our (past) light cone. We have no idea or even an inklinkg what this spacelike extended present could even mean. Now that I mention this, I wonder what the implications for black holes are, where apparently time and space kind of switch, this means there is a phase transition in what it means to be an spacelike extended present. Wonder what it could tell us about it, the black hole dynamics. Considering our current universe would be the spacelike extended present for the black hole at the event horizon where time and space switch roles and flip!
@@classicalmechanic8914It should be possible to see Andromeda (thougj may not be probable) at it is in the present or by a margin of a few seconds (also taking into account delay in our consciousness of reality). That is, thru a wormhole. But if there are naturally more wormholes in the universe, well, we could have been seeing things that are much farther away than they really are, and we are there seeing a mixed of observation of the past in the present.
That was the smoothest segue of introducing a sponsor into a RU-vid video that I have ever seen. Einstein was asked if a femtosecond is the shortest measurement of time. He answered no. The shortest measurement of time is the time between when a traffic light in New York City turns green and when the driver of the car behind you beeps his horn.
Mahesh, all the hard work in the animations and the smooth delivery of explanations are revolutionary and all, but deep down you know you've turned pro when you've seamlessly segue into the sponsor spot without any transition. Achievement unlocked! Einstein says he is proud. It's ok if you didn't hear it, he was in another frame 😉
Andromeda is not just separated from us in space but also equally in time. Just as we can not reach Andromeda in space, we can not reach it in time. We're essentially de-synced in time by 2.5 million years. If we were to travel to Andromeda, that desync in time would shrink as the distance between us shrank. So when we arrive somewhere we don't just arrive there in space, but also in time. Hence the term, spacetime. With that in mind, the "present" is only local to you, and the further something is from you the more in the past it is from you as well.
It is astounding how you've managed to clear up EVERY single follow up question i had after watching your earlier videos (coming in from the triplet paradox video). In three videos you have cleared up questions I've had unanswered for years. You should be required viewing in every science class in every school, anywhere. This is a level of teaching excellence that I've not only never seen before, but never even thought possible.
If the universe is moving forward and you move forward with the universe, did you really move forward yourself? If I were on Mars at 9 o:clock what time would it be here on Earth? It wouldn't relate. The orbit of Mars is not equal to the orbit of Earth so the hours in the day would not even be close. If 1 day of Earth was 3 months of Mars how much older would I be when I get to mars and do I age the same as if I were on Earth? I would age the exact same on either planet of Galaxy. We are moving forward with the universe.
This is why it's good to play with simulators that use a speed of light much slower than normal, so one can develop a better feel for how "now" is relative.
Speed has nothing to do with forward motion. You can go forward at 1 mph. Everything inside of you is only going 1 mph. Nothing inside of you will go faster or slower than you are.
This is the first video that's convinced me that faster-than-light travel is impossible, as it would create causal paradoxes: Lets say we have three FTL communicators, two nearby (B & C), and one in Andromeda (A). Lets say B and C are nearby, but C is jogging. B says to A "tell C to tell me to say 42", then A tells C that, but C will hear that message days before B sent it, so can tell B not to send any message at all, creating a paradox.
That’s not how it works, C will hear the message days before they would be able to observe B sending it but C’s observation of B sending it is irrelevant to affecting wether or not B did send it I swear these misunderstandings are only possible because we’re taught a very self centred version of time. Going faster than the speed of light is not time travel otherwise we already have that with sound you can just go further away faster than the speed of sound and hear what happened earlier than your previous observation but if you were going slower than the speed of light you won’t be seeing before your previous observation. Only difference in your example is now light is the one coming in second place. Edit: I said the same thing twice
I never understood why people believe that faster than light is impossible because otherwise you could get a message before you observe someone sending it... Or that you could meet an alien before you saw them leave their home planet or whatever else. Like none of that means FTL is impossible and isnt at all odd to think about even, nor is it timetravel. Just because you travel say 2c doesnt mean you can affect the past by sending a message somewhere and them being able to send a response before you sent your message. Theyd only be able to send a response before they observed you sending a message, but your message was already sent and received. All this would mean is that you could receive a response at the same time as they observed you sending your original message through light but it wouldnt break anything. Thinking it would break anything is like thinking the fact that you can see someone yell something at a long distance before you can hear them is time travel or breaks the rules of nature. Obviously FTL could well still be impossible no matter how advanced we get, but assuming that its impossible because you could receive information before you observed it being sent is ridiculous. It doesnt break any laws to be able to speak and interact with someone infront of you at the same time as you observe them approaching you from far away, because that person approaching from far away isnt a person, its just photons they gave off arriving after they arrived. If youre going to assume its impossible at least assume it for a sensible reason such as believing we wont ever find a method to go faster than light because it takes too much energy to accelerate mass that much, rather than falsely thinking its some kind of paradox.
@@Borg-mb8qv It's a paradox whether you assume free will or not. The entities at ABC could all be simple transistor circuits, and it would still result in a causal paradox.
If FTL is possible, then it would mean that c is not the speed of light but the speed of whatever travels FTL. We just update that and relativity stays put 😅
6:36 If you are wondering, even a very small speed like 1 meter per second (2.24mph), the time difference would be 3 days if my calculations are correct
Woah hold your horses, the future *does* have a meaning in relativity. It's a mirror of the past: everything that can affect us is in our past, everything we can affect is in our future. It is just that these terms are smaller than in our intuition: at a distance, the past does not touch the future, instead there is a huge timeframe of causally disconnected events where you can't agree whether they are in the past, present or future based on your reference frame (we might as well call all of that "quasipresent" or just "present" if we want, baring in mind it is not a moment in time but a huge region in spacetime).
Oh, I love this. And the topic of the future is really timely. I have been studying the remaining portions of the writings of the pre-socratic philosopher Parmenides of Elea. Really odd stuff. He was of the belief that time was an illusion and that all past, present, and future exist simultaniously. His student was Zeno famous for Zeno's Paradoxes. It has gotten me very interested in the philisophical idea of Eternalism. The fact that even at non-relativistic speeds, different reference frames have different ordering of distant events seems to support this position. But because what is happening distantly can't actually be measured and its information sent to us any faster than light anyway, it ends up leaving the world of science and entering the world of philosophy. Thank you for this video. So good.
Imagine if you will going to Mars for three Earth years and when you get back to Earth you are three years older. Both Earth and Mars moved from day 1 to day 2 at the exact same moment in space. That would be forward motion, not time. Day 1 day 2 day 3 into Tomorrow, the future.
This channel is amazing. You good sir, do an amazing job explaining to people who are not experts. Also love the vibes od the channel, super upbeat and keeps it entertaining.
To address the very last question in the video You explain it very well and ill put it in different words: Someone once explained it to me in a very simple way - each observer: me, the jogger and the aliens in Andromeda have their own time. Imagine it like a track, and the word "now" is a point on that track. Since every one has their own track, the word "now" is personal. Ie each person's now will refer to a point along his own tracks - there is no necessity to be able to map each point on your tracks to some point on another's (arbitrary) tracks. They are simply just different tracks, and each observer has chosen a different path through spacetime. You dont have to be able to link these tracks together, why would you?
In the beginning, when we were at rest and the girl was jogging, she saw that the second clock was slightly "older" (for a lack of a better term). But what happens when she stops as soon as she reaches our position, after the signal was sent? Prior to stopping, she saw the first clock delay because from her FoR everything was moving towards her and the light velocity remained constant, as you said. But when she stops, what does she see? Should the clocks "correct" themselves and become in sync again?
I learned all this from books in the 90’s. Now it is so easy to get this information. I still think it’s worth reading, but using videos like this to supplement is an amazing gift to young scientists or just anyone.
That whole explanation fell apart when 2.5 million years passed. If the runner had been running for 2.5 million years, they wouldn't still be next to you.
Right. If she would be traveling straight into direction of aliens, the light traveling from aliens would have a shorter distance. Therefore guy sitting on a bench would see monday while she sees friday. While all those events happened long time ago and alies are extincted by now.
This one of the greatest physics channels of all time and all reference frames ❤ . Btw mahesh you need to do some videos about quantum mechanics especially the string theory pls 🙏🙏🙏🙏🙏
Dear science educators: PLEASE stop using the idiom “to X, it looks like” to mean “according to X’s mental model”, since X built up that model by *actually looking* at things in some sequence. Looking is a relativistic event with its own spacetime coordinates! Saying “look” confuses us all. It doesn’t “look like” the radio wave hit the far clock first. Instead the jogger *witnesses* photons from the ticking clock after some delay and some motion and some doppler effects and some relativistic dilation effects have also all happened. Without mentioning those you are committing the Newtonian fallacy of assuming an absolute objective universe. (Yes Mahesh eventually gets there. But the damage is done. And this whole problem just an error of word choice, not a paradox.)
What a great video! Loved it! When I first learnt relativity I was very puzzled by the Lorentz transformation for time, t'=gamma(t-vx/c^2). It seemed odd that it contained x. Apparently it implied the change in time depends not only on relative speed but also how far away you are. You can get a big change in time by either having a high speed or a big spatial separation. It literally took me years to realize "so what". If only I'd seen your video back in the day! There is a relativity joke in there somewhere but I can't quite grasp it :D. I wonder if I could persuade you to do a video on spacelike intervals where for some observers the effect comes before the cause?
Watching your videos always allow me to discover something amazing about our world. We are fortunate to have amazing researchers like you to provide us with these hard to grasp knowledges. Thank you
This is a great video on the "relativity of simultaneity." I think a deeper issue really is what is sometimes called the "conventionality of simultaneity," which asks, how do you even define simultaneity to begin with? And yes it is related to the one-way speed of light dilemma as well. I think understanding "conventionality of simultaneity" is helpful to understanding "relativity of simultaneity."
Wow great presentation Mahesh sir 👍🙏, actually "today is tomorrow's yesterday" 😅😅 similarly "present is future's past" and hence as per vedanta everything is relative and predetermined.
Not _exactly_ on topic, but legendary comedian Steven Wright, on a recent Late Show appearance, quoted a line from his new book: "The present is a past factory."
Since I was a little boy, it always made sense to me that free will is an illusion, that the nature of the Universe is deterministic. I stand by it to this day. We are nothing more than just a bunch of particles interacting with each other and all the others around us, no matter how sophisticatedly arranged, we (a bunch of particles) still have to exist and behave by the rules. Things evolve in time with an order, the math and all the unmeasurable amount of variables are just infinitely complicated for our small brains to understand them, much less predict them. Nonetheless, the illusion feels real to us and we should enjoy it and just live our daily lives not caring about it, because in the end it doesn't really matter. Be happy and just enjoy this fascinating, unforgiving and beautiful Universe.
Why can "we( a bunch of particles)" choose to walk up a hill, while all the particles by themselves would follow their world line and universal law of motion and roll down it? Don't we all behave by the same physical rules? Why the contradiction?
The idea that “now” far away has no meaning is partly why I get twitchy when people say the observable universe is something like 90 billion light years across, instead of around 27 billion.
This is crazy as a physics problem. Surely it's one of the only issues in science that challenges something as foundational as time, and the answer is simply that it doesn't matter because humans just aren't capable of understanding what any of the results mean.
@@wesjohnson6833I guess in some ways it's both. It is a universal thing, but at the same time is relative. Regardless, we as humans cannot physically grasp what it means for time to not exist in the way we experience it. So it being both, at the same time, even though it's a paradox, doesn't affect anything.
@@THICCTHICCTHICC Time just has too big a basket to hold all the ways we use it at different levels. Once they dragged entropy into the basket and never let it out on it's own again. And it's still going on. Time truly does persist.
you dr mahesh were my finally stepping stone into "truly" understand advanced physics like relativity and qft, truly is a big word so what i emant what understand it as much as i think is adequate because i dont think we can get those 100% down just yet
If anyone is old enough to remember the days when we had to write letters to communicate, it’s the same idea. If we think of the speed of the letter as the speed of light, then everything is equivalent. I can only read what the other person has written days ago. What they’re doing at my frame of reference’s “now” is unknowable, until days later when I get their letter. Furthermore, if I’m sitting at home and my brother is running out of the house to meet the mailman, my brother is going to get his letter earlier, so working backwards, in his frame of reference, the letter must has been closer to completion when we were both sitting in the house.
My mind hadn't been this blown by physics since learning what neutron stars were a few years ago, and I'd been missing the feeling. Thanks for bringing me back into it.
Noodle Baker here again! In Non-Expanding / Non- Contracting Space: If Stationary Clocks (Stationary in Free Space - Yes, It Matters) - Left Clock and Right Clock both emit a Wave when they are reset to Zero (perfectly synchronized) and then at 1 tick Intervals (set you tick length to however long or short as you like, for greater precision. Lets say 1/10 of a sec), then the waves emanating from each clock will be Perfectly Concentric, Perfectly 1/10 sec Spaced, Perfectly Spherical Shells centered on the Position in Free Space of the Stationary Emitting Clock radiating out at c. Maxwell and Michelson and Morley ALL say so. The perception of any observer located anywhere in space, will depend on their location when the next Perfectly Spherical Shell Wave intersects with the Observer's Instantaneous Location at that time. Maxwell and Michelson and Morley all say so. If the Observer is Stationary (Stationary in Free Space - Yes, It Matters), then the interval between Waves will be Constant (1/10 sec), at the Delay equal to the Propagation Latency from the Position in Free Space of the Stationary Emitting Clock to the Position in Free Space of the Stationary Observer, but at equal Wave Spacing, so the ticks of both clocks will not necessarily be in sync, but will each tick at a constant 1/10 sec interval/frequency, with the further clock delayed by the further propagation delay (the difference between the Propagation Time from the Position in Free Space of the Stationary Further Clock minus the Propagation Time from the Position in Free Space of the Stationary Nearer Clock). An Observer equidistant to Both Clocks, will observer both clocks at the Same Propagation Delay (the difference between the Propagation Time from the Position in Free Space of the Stationary Further Clock minus the Propagation Time from the Position in Free Space of the Stationary Nearer Clock is Zero), so the ticks of both clocks will be perfectly in sync, each ticking at a constant 1/10 sec interval/frequency, but at the same Propagation Delay. If the Observer is moving, it DOES NOT MATTER if the Observer moves in one step in the interval between the arrival of two sequential Waves and stops, or is constantly moving, and if constantly moving, is moving at constant speed in any direction (positive or negative velocity), or accelerating or decelerating, or accelerating and decelerating, or any other mode of movement imaginable, the Observer will perceive the Next Tick when the Observer's Exact Instantaneous Location is Exactly The Same as the Instantaneous Location of the Perfectly Concentric, Perfectly 1/10 sec Spaced, Perfectly Spherical Shell from the Position in Free Space of the Stationary Emitting Clock. Maxwell and Michelson and Morley all say so. If the Moving Observer is moving along the Orthogonal Vector from the Observer's Instantaneous Location to the Position in Free Space of the Stationary Emitting Clock, then the Cosine of the Angle is 1 (or close to 1, and so can be ignored by the Small Angle Approximation). However, if the Moving Observer is not moving along the Orthogonal Vector from the Observer's Instantaneous Location to the Position in Free Space of the Stationary Emitting Clock, then the Cosine of the Angle is not 1 (cannot be ignored by the Small Angle Approximation), and MUST be considered as the interval along the Vector of Travel will not be the same as the Perfectly Concentric, Perfectly 1/10 sec Spaced, Perfectly Spherical Shell from the Position in Free Space of the Stationary Emitting Clock. If the Trajectory of the Moving Observer is a Straight Line in Free Space at some angle other than along the Orthogonal Vector from the Observer's Instantaneous Location to the Position in Free Space of the Stationary Emitting Clock, then the Interval between the Ticks / Waves will be constantly Changing as the angle to the Orthogonal Vector changes and therefore the duration between consecutive waves MUST BE Longer or Shorter than the 1/10 sec duration between those same consecutive waves along the Orthogonal Vector from the Observer's Instantaneous Location to the Position in Free Space of the Stationary Emitting Clock. It does not matter how or why, or in which direction the Observer moved, but the change in the Angle, and therefore the change in the Cosine of the Angle of the Vector of Travel to the Orthogonal Vector from the Observer's Instantaneous Location to the Position in Free Space of the Stationary Emitting Clock (if not negligible so that it cannot be ignored by the Small Angle Approximation) is what you are referring to as Time Dilation. This is Not! It is of course Doppler Shift! In the limit, (which of course Does Not Exist if you believe that the Absolute Minimum Length is the Planck Length and the Absolute Minimum Time is the Planck Time, as there is no Absolute Zero of Interval between, and Distance between Ticks). then the Instantaneous interval between any two Consecutive Waves will not be Constant but will be Constantly Changing, either adding to and accumulating Greater Delay from the Observer's Instantaneous Location in Free Space to the Position in Free Space of the Stationary Emitting Clock. The Time Observed on the Remote Clock will appear to the Observer to be changing almost randomly as the Observer moves around in any other path than a Straight Line, Speeding Up, or Slowing Down as the difference between the Propagation Latencies from the Position in Free Space of the Stationary Clock to the Instantaneous Position in Free Space of the Observer for consecutive Ticks increases or decreases the Propagation Latency from the Position in Free Space of the Stationary Clock to the Instantaneous Position in Free Space of the Observer for the next Wave / Photon. If the Remote Clock is NOT Stationary in Free Space (Yes, It Matters), then Every Tick / Wave / Photon, is NOT propagated from a single unchanging location, and so the Waves will NOT be Perfectly Concentric, Perfectly 1/10 sec Spaced, Perfectly Spherical Shells centered on the Position in Free Space of the Stationary Emitting Clock, but will instead each be a totally independent Wave emanating from its own Launch Location radiating out in a Single Perfectly Spherical Shell centered on the Instantaneous Position in Free Space of the Moving Emitting Clock, radiating out at c. Maxwell and Michelson and Morley ALL say so. This has absolutely nothing to do with any movement of the Observer. The Perceived Location of the Moving Clock AND the Perceived Time on the Moving Clock as perceived by the Observer will depend on when each non-Centric Perfectly Spherical Shell arrives at the Instantaneous Location in Free Space of the Observer, regardless of the previous Location(s) in Free Space of the Observer when the previous non-Centric Perfectly Spherical Shell Waves arrived, or the Location(s) in Free Space of the Observer when the subsequent non-Centric Perfectly Spherical Shells arrive... If Free Space itself is NOT Stationary, but is in fact expanding or contracting, or bending due to Gravity (Does it? Assuming for now that it does, and is not due to something else...) (Yes, It All Matters), then the Propagation latency of Every Tick / Wave / Photon from the Instantaneous Location in Free Space of the Emitter on Emission to the Instantaneous Location in Free Space of the Observer on Observation will be affected by the change in distance due to the change in density of Free Space between the Current Location In Free Space of the Tick / Wave / Photon and the Instantaneous Location in Free Space of the Observer on Observation, when the Tick / Wave / Photon converges on that Instantaneous Location in Free Space. This is of course entirely independent of any motion of the Emitter or Observer, as the Instantaneous Location in Free Space of the Emitter on Emission AND the Instantaneous Location in Free Space of the Observer on Observation are Known Precisely, and so their respective motions, directions, velocities, accelerations or decelerations, are by definition Absolutely Indeterminate!
Haven't you sat in a car, bus, train or plane? From your perspective aren't you stationary? From outsider's perspective you moving at 600km/hour(in plane)
@@vedprakashtiwari6438 I meant it as a play on words, in the sense: when I’m jogging/running, with heart rate 180 and dripping in sweat - although it’s technically correct to call myself (from my reference frame) “at rest”, it is a very unfortunate choice of words in this context haha :)) But yes, I know what you mean, it’s a fascinating thing! As a kid I used to wonder why we couldn’t go faster than the cars passing by in the opposite direction :P
I recently read a book about an event which took place in the 1700s. A ship wrecked and a group of people survived, and eventually made it back to England, where they were from. In the time between the wreck, and the eventual return of some of the people, the people had been declared dead, the families had moved on, etc. Once new information came to light, it complicated things. It makes me think, before we had near instantaneous communication through telegraph, or eventually radio and light waves here on Earth, there wasn't even always an agreed upon, "NOW." In the same, "NOW," those people were declared dead in one part of the world, they were still struggling to survive in another.
Time - 13:43 "But what will he say, uh-uh, Mahesh, that time is this it's currently one light second away but it's coming towards me which means when this photo was created it was slightly further away from the clock when it was just sent it was more than a light second away which means the photo has been traveling for more than 1 second so this photo "More than 1 second has passed since it was created, so the clock there should be reading just over 1 second." If the photo of the watch shows a little more than 1 second ahead of the runner, shouldn't the distant watch be showing a little more than 4 seconds behind at that moment?
Ok, weird thought. Notice the entire background moving toward the jogger as a single unit. All the clocks, moving as one, would become quantumly entrained. All the clocks then, would be in synch with the first clock that the jogger observed, speed of light becomes irrelevant as for when each clock starts.
It makes total sense that something more distant would have to happen first for it to arrive at the same time as a closer action. Even though the clock would start first, wouldn’t the clock need to send out a new photon saying that it started and was now in motion? Now this photon would have to travel a bit farther than the nearer clock. And while the second clock started later, the photon it emits when it starts doesn’t have to travel as far before it reaches the runner. So wouldn’t both clocks still appear to her to start at the same time as long as she had not run past the nearer clock, but if she had run by it, it will be hard to keep both clocks in a field of vision to judge simultaneity. If she runs past the nearby clock, the total distance traveled would no longer be the same for the two phases. 1st phase light travels from source to clocks. 2nd phase light travels from clocks to runner. The only way she can tell which one started first is if she knows which clock started farther away. If you have 2 colleagues arriving at your house and both arrive at the same time, and both traveled at exactly the same speed and I ask which colleague left their house first that is not possible to know unless knew the total distance each of them traveled. The only way they left at the same time is if they both had to travel the same distance. Otherwise one of the two must have started first to appear to arrive at the same time. But which one that is, would seem impossible to know. Because they appear to arrive simultaneously. So as long as her velocity remained constant and the rate of change in distance between the two clocks was the same, I would think both clocks would appear to hit 5 seconds simultaneously. If she is running at an angle though I would think that would create issues as the distance between the two would no longer be linear? There is also the fact that are brain will fill in information that might not be there, to help us create structure around us. So again I believe she would appear to see them simultaneously even though they might not technically be simultaneous. However it would also then suggest that the rate of the second will not be the same between the two clocks from her perspective. After all the human eye is likely only going to be sensitive enough to detect a several millisecond difference.
this is the first time I hear about this paradox by name. This is also the first time I see someone trying to explain the idea of "but something must be happening NOW somewhere else!". It is a very hard concept to grasp since on earth we all basically share the same "now". Mindblowned.
When she's running towards the clock and sees the picture and concludes the clock must've been farther away, the fact that length contraction also takes place just confuses the whole thing for me.
Fantastic explanation of the Andromeda Paradox! Apropos, the way you advertised squarespace was also great. I guess this was the first time I watched an advertisement until the end 😄.
Finally someone is talking about this simple example to explain the illusion of past/present/future. It's happening in front of our eyes but hardly anyone use this as an example. There can't be a better example than night sky. It's so simple yet so fascinating. Thank You.
There's a loop hole! As we see the world bcz light reflection on our ratina through lens, if that clock appears to move toward the jogger then light must try to avoid the paradox to happen, it's like equilibrium try to make this as was in past
Tough to completly understand, but was still fun the parts o got. I wonder if it would be worthwhile getting into the perspective of the aliens on their frames of refrence.
The concept of now, gets even more shaky when you consider the variable processing delay for our own sensory organs and brain. Also discrepancies between the speed of light and sound can mess things up further, if you are at say, a large drive-in theatre, and you can somehow hear the speakers on a car much closer to the screen than you, the sound can be out of sync with what you see even though it is fine for the people in that car.
This is why I drive my car so carefully, what I see with other vehicle's position and velocities all takes place in a moving frame, me being at rest, so it's obvious that nothing is where I perceive it. It still is amazing how little power is required by the engine to accelerate the entire Universe. At least if I'm running late, moving the Universe just a little faster means I'm traveling backwards in time.
fyi that's classical relativity, not Einsteinian relativity, you're experiencing, and that (flawed but roughly accurate) model doesn't have any paradoxes of simultaneity -- still pretty cool you have a Universal Accelerator Pedal though! :)
This is only from Special Relativity, it changes significantly when you add in General Relativity and Gravitational time dilation. The inclusion of Gravitational time dilation removes the distance portion and allows for more close-up immediate impacts. Not getting into the details however various governments have been using EM fields to manipulate Gravity since WW1 (Tesla admits to this in June 1919), we see these today as UAP. The sphere of distortion is a gravitational lens. The acceleration, deceleration, and motions which has been verifed by the US government since 2021 are themselves explanable using gravitational and kinematic time dilation, hence the illusion of hypersonic speeds without the production of a sonic boom, its the difference in relative time dilation due to the manipulation of spacetime curvatures using EM fields. I myself have experimentally done this using mid-sized Tesla coils and atomic clocks and produced up to 8 months of time dilation. Tesla was using much larger systems and was able to produce time dilation of up to 100 years, hence his 1926 description of the smartphone.
Great one 👍 got my sub. I watched your video on causality with Einstein's slap,😶🌫️ and this video ties it together well. The sp.of light is really the speed of causality, or "the speed of information." These observers musn't worry about those cunning Aliens invading sooner than expected because the Aliens can't outrun the information that is constantly spying on them for us. 👽〰️🔭👀
The size of now gets wider (and therefore less defined) as you get farther away because it is defined as the region outside your past and future light cones.
Two issues/questions here: How did you end up with a farther clock being ahead by more femtoseconds? The femtosecond difference arose purely due to the joggers velocity. Second, we never talked about length contraction of the distance between clocks when viewed from the joggers perspective. Thanks for your enthusiastic and inspirational videos :)
I know that you said that the clocks are actually not required but in reality you can't even have two synchronised clocks in the first place. You see when you synchronise them and move them away, they unsync due to time dilation
It would also seem that the only way that the time difference between distant clocks would continue to increase is if the jogger never stopped running. There is also the problem that she is on a planet that rotates, and at some point in time she will turn and start running backwards as the planet rotates around. So it would seem for her to disagree on an event in the andromeda by 2 days, she would need to be continuously running towards andromeda, and she would actually need to be on earth 2 days closer to the event. But this also implies that you both agree on what day it is in 2 million years if she has been running for the whole time. But if you consider 1 day to be a revolution around the sun, while both the runner and stationary observer might disagree how many seconds are in that day, the day would be a day.
I KNEW jogging was a bad idea. So, the "realness" of events in Andromeda depends on the actual interaction with our local environment? I can live with that. I'm at rest anyways.
What about a supernova explosion in the Andromeda Galaxy that is visible here? So the jogger saw the explosion days before the benchsitter does? She can remark to the benchsitter that she saw an event before it’s happened in his perspective?
The apparent paradox is not due to the physics but psychology. We assume that time flows at the same rate everywhere, so there is a universal "now", but it's not the case. It's similar to the way people think mirrors reverse images left-to-right because we're used to rotating on a vertical axis. Mirrors actually reverse images front-to-back.
And because we imagine ourselves looking out from the reflection's POV due to being wired for human empathy and to see faces in other things (understandable since it otherwise looks exactly like our face). So we see the hand on the right as the reflection's left hand, even though we can plainly see that the hand is still on our right so isn't flipped.
I am feeling proud that there are still some teachers in India who rather than just following very bad and wrong education style and system, changing the way to look at physics with another perspective and explaining real majic of universe with physics. One is you amd other one is Vigyan Recharge
The clocks and the radio wave must be thought of as a system; the clocks and the radio wave are all moving toward the runner as a group, and therefore, both clocks are started at the same time.
You expressed this idea as a negative statement ("the idea of now, far away, has no meaning") but isn't the true takeaway actually positive, that is, that the idea of spacetime is necessary and therefore we really do live in four dimensions?
Did you not forgot to take into account length contraction? To make this more apparent, if the moving observer is moving at 86.6% light speed (so the distances are halved), the 1 light year distance for him (stationary) is half a light year to her (the moving observer). This means when they both see the 4 on the clock, she sees the clock only half a light year away, and assumes the light traveled LESS than 1 second...
Big bang happened at the same time for Andromeda and Milky Way. Time 0 of our universe. If you roll everything back Andromeda and us will be again together at the same exact time. At each point in time of that rolling back (ie 70%, 50%, 95% etc) we can say that that is the cosmic now. We can’t measure it with light because it has a finite speed, but this doesn’t mean that a universal now does not exist. My 2 cents.
in the universe, to understand it, maybe try to put the base in the frame in the "place and time" of big bang and explode your ideas.... if you check red-blue shift, its impossible to understand "where" is the center of the universe ("the place where big band happened") because everything was there.... that line could bring you another amazing video.... hope to check it! thanks!
