Does the future already exist? (Andromeda Paradox)

A special relativity paradox at 3 miles/hour!
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This video focusses on the Andromeda Paradox. This paradox is caused due to the relativity of simultaneity. A consequence of Einstein's special theory of relativity.

[@PCstepsGR]

I discovered your channel two days ago, and you have become my favorite science communicator by far! Keep up the great work!

[@Mahesh_Shenoy]

Great to hear that :) Welcome aboard :)

[@alexandroschotzoglou6963]

Exactly what happened to me. Great channel!

[@physics6063]

Sir Thoda Hindi mein bhi bola Karo kabhi kabhi samajh nahi aata hai​@@Mahesh_Shenoy

[@Shrodinguer4321]

Same

[@MrFeanor82]

Ditto. This channel is soooo intuitive, and profound. Every. Single. Episode.

[@thedeemon]

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]

Thanks for the recommendation :)

[@classicalmechanic8914]

@@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.

[@rockingediting652]

​@@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.

[@Robinson8491]

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!

[@rbr1170]

​@@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.

[@martinschwartz7342]

That was the smoothest segue of introducing a sponsor into a KZbin 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.

[@HarryS77]

I hate it, but I respect it.

[@slam_down]

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 😉

[@akaHarvesteR]

It's ok, he will hear about it in about 1 or 2 million years.

[@akaHarvesteR]

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.

[@rafaelgonzalez4175]

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.

[@Nuovoswiss]

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.

[@Borg-mb8qv]

It's only a paradox if you assume free will 😊

[@gregc9344]

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

[@andrek6920]

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.

[@Nuovoswiss]

@@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.

[@Mahesh_Shenoy]

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 😅

[@jeffdeupree7232]

You always ask and answer the questions I have after watching other videos. Love it! Keep up the good work.

[@iambarabanov1]

Never had i seen such a natural integration of an ad . Very nice job Mahesh!

[@kylelochlann5053]

The Andromeda Paradox exemplifies that all of physics happens along time-like curves.

[@matthewtheobald1231]

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.

[@NewMessage]

Ok. dude turned a commercial for website building into an existential crisis.

[@ambesangbong4245]

Ikr.... very cool

[@adarshdinesh6827]

😂

[@rafaelgonzalez4175]

It is all a lie. Time is not relevant to anything other than Earth.

[@srh2277-nd9dh]

Ur literally my favourite youtuber, ur vids r the most interesting to me in yt than any other, Tq Mahesh sir for making these amazing cool explainer videos. And I'm v happy to see this channel growing in good pace, congrats for 100k subs, but i feel it's still underrated, u deserve a lot more than this and i think ull achieve that soon.

[@maximalideal1525]

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."

[@klosnj11]

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.

[@cmilkau]

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).

[@perfectionbox]

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.

[@rafaelgonzalez4175]

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.

[@sock1533]

The clocks at the start not having a 9 is hurting my soul

[@kxqe]

And they have no zero either, so they are already one second in the future before they start.

[@Mahesh_Shenoy]

Omg! I was sleep deprived. 😅

[@rafaelgonzalez4175]

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.

[@soumyadipbiswas9074]

Sir, Please keep sending us more of your Photons and Phonons recorded from non existing now to the Future

[@Learner..]

Ah ys

[@tylerljohnson]

I was jogging last week and totally knew that smooth squarespace segue was/is/will coming up.

[@DJ_Force]

You are one of the best educators on Relativity out there today.

[@robwilliams4773]

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?

[@alexanderdede6354]

Wow. The way you integrated Squarespace was amazing!

[@tigermatty]

Smooth af

[@rafaelvongehlen1]

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 😄.

[@SmithsMobile]

Love your uploads, you were born to do this 😊

[@Shrodinguer4321]

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 🙏🙏🙏🙏🙏

[@heisenberg2514]

You are like a big brother to me, who simplify the core and hard concepts for me in the easiest way possible Take love

[@kailashanand5086]

thanks for messing with my head again got something new to think about for the next week great vid!!

[@swamynathansanthanam1812]

Happy to see you back sir. Expecting you to appear on screen frequently instead of from time to time.

[@smokeybobca]

Depends on your relative motion to Mahesh.

[@luudest]

This is most special channel about special relativity!

[@tdahanayake]

Great! Please do a video on gravitational time dilation as well and also videos on general relativity.

[@Mahesh_Shenoy]

Yup, I have a few more to cover in special relativity, then I ll move to general relativity:)

[@TimJBenham]

"The distinction between the past, present and future is only a stubbornly persistent illusion" -- Albert Einstein, 1922.

[@michaelcox436]

Best job of working your sponsor into the content I've ever seen.

[@harrisbinkhurram]

Once again our brother is back with his conversations with Einstein.

[@pratyushgora]

8:46 this gave me goosebumps

[@annamalayadevi]

I see this at 8:47 means I'm more fatigued at this moment 🥴

[@justinsymington]

Just discovered your channel and am binging all your videos. You're amazing. I love you! Your enthusiasm is infectious. And when you stop and are like "wait einstein what about this" your questions are exactly the questions that I have as you're talking, your flow is so perfect for me.

[@ChrisCM23]

Subscribed. Incredible way of thinking about so many ideas. 👍👍

[@sergey_a]

However, this means that any long-distance teleportation becomes an ideal time machine. As is FTL communication or FTL drive.

[@KhushiKukreja2]

But then the question arises that how can we make teleportation possible even in the first place

[@kroneexe]

4head thread

[@satyavatikola168]

Sir please make videos in physics in khan academy too why do you stop making videos btw I love your teaching skills sir 🥰

[@enriquea.fonolla4495]

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.

[@NitinRangani]

I understood relatively perfectly for the first time. Thank you

[@vinodtavildar]

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.

[@renatocarvalho6059]

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.

[@wesjohnson6833]

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?

[@destrygriffith3972]

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.

[@mylittleelectron6606]

This was really fun. And I love your energy!

[@dfwdeadshot9557]

I was thinking about this a few days ago while driving thanks for posting this video

[@Krokodil986]

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?

[@TheKingWhoWins]

If you want to try to make "objective" sense of the situation than it would seem as if you would have to try and link them together.

[@Krokodil986]

@@TheKingWhoWins which can only be done meaningfully if they meet again

[@arnavharer1426]

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

[@ethanmendelson6978]

Fantastic explanation. New favorite physics channel.

[@user-wu4yo4qr6h]

Awesome video, thanks. You’re a great communicator

[@Mahesh_Shenoy]

Thanks :)

[@onlyeyeno]

@FloatHeadPhysics So "in VERY short": Causality travels at the speed of light, hence talking about "now" (aka simultaneity between events) regarding something that is not absolutely sharing our point in space(time) is purely hypothetical... Because it will remain unknown until the light from the events reach us... That's at least how it appears to me "now" ;)... And thanks for another fantastically entertaining AND thought provoking AND informative video... That is quite the feat, and very much of it is due to Your personal presentation, Your apparent enthusiasm and engagement really "sells it" imho ((Of course I understand and appreciate that there is a LOT of hard work in making good approachable and easily understandable explanations to make that even possible)). And I hope You manage to keep it up, and get the well deserved recognition and success that You deserve. Best regards.

[@infinitum-repertorium]

I'm watching and at 5:33 I understood where we're going. I love these aha-moments. Great video!

[@wizardsuth]

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.

[@logicianbones]

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.

[@davejblair]

What a superb channel!! Such a wonderful and engaging way of explaining these concepts. I love it ♥

[@sjzara]

Brilliant video. Nice explanation of the “paradox”.

[@hakanbalki902]

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?

[@BuckeyeStormsProductions]

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.

[@barlow2976]

Great presentation, I've subbed. Free will is indeed an illusion.

[@TheVitzy]

absolutely loving this content! thank you

[@ohedd]

I don't know why, but my favorite aspect of these videos is the Socratic setup between him and Einstein. I love when Einstein goes: "BUT MAHESH!"

[@Steaphany]

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.

[@possibledog]

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! :)

[@MrBollocks10]

I love the way you speak. It's halfway to singing. The Welsh are the same.

[@donpeters9534]

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!

[@alexsteffen2942]

The paradox comes from taking time out of the equation and assuming the three reference frames can be looked at as a snapshot. If you isolate Andromeda (A), B, and C, and say C is moving at 5km/h. A Lorentz transformation tells you that C will see an event 4.23 days earlier than B. But to say that this means C "sees a different now" than B for Andromeda is misleading. If those reference frames do not change, and C continues at 5km/h until light from A reaches B, then all three frames are now causally connected, you can calculate that C traveled (5x24x365x2,500,000=1,095,000,000km) 4.23 light days. C isn't seeing a different "now" for Andromeda, C will see events from Andromeda earlier than B because C is moving closer to Andromeda and will meet the light from Andromeda sooner if the reference frames do not change.

[@archy2j]

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.

[@jamiecoleshill2182]

Love the way you tied in determination and the promo for squarespace...

[@433Highlights]

The new quality of the videos is awesome

[@astrophage381]

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 :)

[@Robinson8491]

This was a great video! Do you take the perspective of 'past light cone presentism' in this view? It seems to me, and it makes sense to me! Thanks to your previous video, I did research on the RPP argument (Andromeda argument) and i found a nice review paper on it, called On the Rietdijk Putnam Maxwell argument. It says there is horizontal spacelike presentism (which is what people generally think about when 'something is happening at Andromeda NOW'), bowtie presentism and as you now explain past light cone presentism. This stuff is truly fascinating, as indeed you are right all we can say is that Andromeda's present is in the spacelike area of OUR light cone. I do think we can still get meaning out of an absolute present and absolute simultaneity in General Relativity though, please I would like to hear your thoughts on this. Flat spacetime, without gravitational time dilation in it, should necessarily have the same proper time propagation, and thus be absolutely simultaneous am I right? Love to hear your thoughts on this, whether in GR flat empty spacetime is necessarily simultaneous when seen from the definitions of a proper time perspective.

[@repairstudio4940]

I love your content! It puts my 🧠 to work.

[@gaurav72729]

Please make some videos on other topics also

[@Sol-En]

You are brilliant lector !

[@justicewillprevail1106]

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

[@jamiecoleshill2182]

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.

[@venoltar]

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.

[@civildiscourse2000]

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."

[@gameraiderislive]

pretty great video man but i have a request umm can you plz let us use the ppt you are making for the video? that would be great

[@vijayabharathimarupudi3484]

mahesh I have a doubt .please clarify .IN the video moving charges magnetic fields ,you said electrons length increases in conductor .I don't understand that .In proton perspective ,proton is stationery and electrons are moving .Then length should decrease for electrons .In electrons perspective electron is static and protons length decreases in conducter. This I understood

[@astrokevin92]

Hi Mahesh. I loved the video, thank you. But I have a question. At around 13:30 you point out that the jogger will claim that the light has been travelling for more than 1 second. But haven't you overlooked that the two clocks will be less than 1 light second apart (to her) because she is running? Or is this effect perhaps less significant?

[@Mahesh_Shenoy]

Good catch 🙆 The distance would be length contracted. But, it still works out to be more than 1 second!

[@astrokevin92]

@@Mahesh_Shenoy Thanks!

[@DrDeuteron]

Except the Lorentz factor at low speed is g = 1 + v^2/2, while clock bias goes as x*v, so you can always pick v and X so g doesn’t matter to first order.

[@astrokevin92]

@@DrDeuteron Yes, I came to a similar conclusion once I took a little more time to think about it.

[@georgerevell5643]

This is just so damn awesome, I"m going to write an article about this for my physics page inspired by your awesome explanation.

[@Chris-cs7nv]

very nice video. I still think that now exists even far away it's just that we would have to wait until light reaches us or if that can't happen then we can't have any information about it. I don't know if that's different from what you were saying because for example we can't see now now when looking far away. We can't see it when looking closer either but it's so close we don't even notice

[@AdritoMitra]

Sir I have a confusion sir if now is not 'now' then time traveling is what you are traveling to the past??? Love your videos and please make the paradox of quantum mechanics ❤❤❤❤❤❤

[@TFayas]

I think the next thing you should cover is that we don't actually know the one way speed of light, only the average of the two way. Would be awesome to get some animations of how length contraction and time dilation negate detection of any difference, and what implications there would be in terms of past present and future if say the speed of light went infinitely fast one way and half speed the other!

[@DrDeuteron]

That is niche physics and doesn’t help noobs understand relativity.

[@TFayas]

@@DrDeuteron you could consider relativity of causality also niche, the best part of physics is trying to wrap your mind around crazy topics!

[@parthvarasani495]

13:13 i am not convinced to this , because as soon as the clock reached at the same place as rest observer clock was then if light signal coming out from the clock will need to be travel 1 light sec distance(as speed of light for both observer must be same meaning we can't add any frame's speed to the speed of light so she can't say that the signal receiving by her is travelled more than speed of light as all other things are moving backward with respect to her ) so both observer sees the same time ticking. Kindly correct me if wrong or convince me by other examples.

[@jamesjames1364]

Bravo, bravo, bravo, to you! You made this so easy to understand. Thank you!

[@matematicaluan]

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!

[@jameswebb3410]

I dont think that the future already existing takes necessarily anythin away from free will. Yes, it might already exist, but the form of this already existing future still depends on the choice you consciously made. Your choices are still really yours.

[@itsoktoberight4431]

It sounds like the same arguement of whether light would come out of a torch moving at light speed at double the speed of light. I think this also relates to gravitational time dilation where time moves faster at the top of a skyscraper than it does at the bottom

[@YanivGorali]

Loved this one

[@perfectionbox]

One can still entertain the idea of a distant "now", but borrow a quantum mechanical concept and introduce probability. If e.g. you see a car traveling on a distant planet a light-hour away, and the car is on a long gentle road with no rest stops, it's reasonable to assign a high probability that what is happening "now" over there is that the car is still traveling on the road. Likewise, if you see a huge steel building, it's almost certain to exist in the distant "now" as well. So the future becomes a fuzzy set of possible outcomes but some are more likely than others, creating probability waves.

[@DeannaGilbert616]

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.

[@chrisbragg7909]

Awesome videos man. No flux given!

[@b0nes95]

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.

[@algirdasltu1389]

This guy is making physics way simpler for me

[@hugegamer5988]

The cool thing is if there is no flux given, with respect to spacetime curvature, then we have perfectly flat space and time becomes much more consistent between disparate observers.

[@BisexualPlagueDoctor]

Except every time you go faster, the time experienced is reduced, so even though it feels like it should suddenly do this, it just doesn’t, because any acceleration directly cancels this out because it is relative, relativity includes time, not just space, and if this did apply that would mean you could just go faster than the speed of light as every time you accelerate your go faster and faster and faster The major upset for all this is that no matter the distance the change in time experienced will always be the same for the same amount of time of acceleration, and if the signal is sent at the same time it will be the same for both individuals, but more time will be experienced internally for one, the external will always have the same affect on everyone because of how relativity works, this is why things can be more light years away from us than the age of the universe is in years, because of the bizarreness of relativity. If you go fast enough to observe a change and you relay that to someone, that change will have happened at the exact same time for them as you say it happened, like for instance at a light second away, the person, while it seems like they should have seen the thing just a little bit faster, the actual time it reached them will be the exact same since the signal doesn't just run away from the object at the speed you move towards it, it goes irrespective of it, but time will change to directly and exactly combat this allowing for them to perfectly cancel eachother out. If, say, they reach a signal in a way that should be faster than the speed they were going, due to relativity, they didn’t, er well kind of. This affect cannot be observed magically over a massive distance just by jogging, as it’s not a shift in the speed of light, it’s just a shift in its location respective of its origin, so no matter what, any object that isn’t accelerating should experience it the same, and if it is accelerating, in which the amount of times required to observe the change is massive, and since they would get very close to the speed of light, by the time it stopped it would’ve happened a bit ago which may be what your explaining, but there wouldn’t be an observable change outside of the relay of information from both parties not matching up, but once they are both at a stationary point it will match up perfectly, just the time it took for the signal to occur would be slower since they experience more time than the other, but the external signal would show the same results, and any other changes would be impossible to calculate due to relativity, but theoretically if the magically started their clocks at the same time as eachother and the signal that is sent to the clocks, and had precise enough instruments to measure extremely small changes, it would be different as you say, a significantly easier way to account for this is have both parties be at rest when the signal is sent and have one move towards or away from it, in which even after accounting for distance travelled the time would no longer sync up. This is accurate to how it theoretically does work, but the differences would be absolutely impossible to calculate in any regard and both observers will same the same thing to the same signal, and both, if separated by let’s say a light day, would believe they were the ones seeing further into the future than the other, even if exact same conditions to the distant object

[@mohitrohilla8147]

Sir "[Please make a video on all type of Resonance]" with many examples ,and also tesla coil and it's resonance concept, vibration etc

[@PulseCodeMusic]

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.

[@prdoyle]

Another example of relativity at normal speeds is magnetism caused by electric currents. That happens at very very low speeds (about 1mm per second).

[@oIIIAdamIIIo]

I have a question for you Mahesh: In the case of celestial events that happen over short times (such as this year's expected appearance of the T Corona Borealis going nova), I wonder if we could leverage the Andromeda Paradox in this way: Set up a series of telescopes on circular tracks, so that there's at least one telescope traveling quickly in any given direction at any given time. Since at least one would be moving quickly in the direction of an event (seeing "ahead" multiple days), it can relay this information to stationary telescopes to prepare to measure the event. The moving telescopes would be garbage for sensitive data, but they could help us prepare to make good observations, by telling us about the more obvious events before they occur. Do you think this is possible? EDIT: I worked it out. T Corona Borealis is 2.8k light years away. A telescope moving at 5m/s would only grant ~24.5 min of advanced viewing. This might be a better job for satellites in orbit. A satellite traveling directly towards the event at 28.8km/h would catch it about 24h in advance. The advanced warning would increase with distance to the event.

[@fishboy3612]

So I’ve heard of the double slit experiment and the double slit time experiment. But what about the double moving slit relative time experiment or double moving slit experiment were we have two things that can be observed if they are affected by light or not and one moves and is hit by the light then the other stays still and is hit by the light at a different time. Can we duplicate photon energy?