We all move at the Speed of Light

[@AntonFetzer]

I have been studying physics at university level for 7 years now and this just blew my mind. None of my lectures ever managed to make relativity understandable. I have always just accepted the math and moved on, but you managed to explain spacetime without using any equation or symbols at all !!!

[@oluwafisayo3676]

It's really impressive. I feel like they just unlocked my brain.

[@lorenzoh.6571]

The channel is using the visual format to its maximum. Then the narration explains the visuals so they don't have to show the abstract equations. Very impressive

[@samuelegbosimba6221]

@Allen Shut up dumb prick.

[@Trancecend]

PBS Spacetime could learn a thing or two from this channel. Their videos always relies heavily on the math, which will elude most people except those with a university degree in physics or math.

[@lorenzoh.6571]

@@Trancecend that's a good thing. We can start learning about the concept on this channel then learn more details on the other channel. Like there are levels to understanding something.

[@daviddlamini4290]

This has made me truly understand why time is a dimension

[@mlucasl]

Not in all theories, time could not be a dimension, but a mix of many. Time could be a variable dependant over space-time. Is not truly know any much of this, and building over it is where many theories come over (like strings). Time could not be an independent dimension (like in a differential equation), because density and speed could "influence" time, taking into account that falling (through gravity) is also partially speed. The previous could talk of 5 dimensions (and 9 in some string theories), where time is co-dependent. But wait... if you take 3 axis dimensions and "rotate" them 45 degrees, or transform them into polar nomenclature, you get 3 other dimensions, so yes, as time could be an equation over density, density could be an equation over time. All these theories build over space-time, and space-time is different from space, and time. Also some errors in the video, antimatter doesn't go against regular physics, antimatter follow the same rules of gravity and not of negative gravity, what is investigated is the bast space of the maybe existent "black matter".

[@mlucasl]

"The overwhelming consensus among physicists is that antimatter has positive mass and should be affected by gravity just like normal matter. Direct experiments on neutral antihydrogen have not been sensitive enough to detect any difference between the gravitational interaction of antimatter, compared to normal matter". It could be that antimatter has negative mass, but is not a consensus neither an empirical test.

[@mlucasl]

@Allen Why? Because there is not a consensus on whether anti-matter has positive or negative gravity. Or because there is not a consensus even on string theory. Or maybe that there is not even a consensus on whether time is a dimension to not.

[@АндрейБ-у4ю]

The fun part is that it is not. You can totally see in the video that time is a property of observer and is relative to it. E.g twins paradox - two different time "points" in a single space-time "point" because there are two observers. The other dimension is not time as we see it. It's something completely opposite.

[@mlucasl]

@@АндрейБ-у4ю but yet again, any dimension can be distorted. And having 2 reference is not a proof or disproof of it. Even space (as dimension) can be altered near dense objects. So you could argue that space too is not a dimension, the reasoning behind (space-time continuum); hence you end with multiple hypotheses. The most acclaimed is space-time but is not the only one. And there is no full consensus as there is no consensus over anti-matter having 'anti-gravity' (that here is taken for granted).

[@minnieroff12]

I have never understood “time” when it comes to space time. I’ve watch a ridiculous number of physics videos on the subject trying to explain it. This is the first one that makes sense to me. Thank you!

[@djnone8137]

Time is a metaphysical tapestry on a loom...

[@fanatamon]

Watch the time = causes gravity video quite interesting.

[@TheMacster555]

Me too!

[@literallynothinghere9089]

link?@@fanatamon

[@Mavrik9000]

0:05 *Introduction* - The introduction explains that while the expansion of the universe can accelerate objects faster than the speed of light, this is not true movement. It is due to the underlying expansion of space itself. 0:51 *Special Relativity* - Special relativity shows that as an object's speed increases, its time slows down compared to a stationary observer's time. At the speed of light, time would stop. However, one cannot go faster than light or go backwards in time by going faster than light. There is a curve connecting speed and time, not a straight line. 3:37 *The Circle* - The curve connecting speed and time is a quarter circle. All objects in the universe lie on this curve. Negative speed just means movement in the opposite direction. It is impossible to go beyond the speed of light or 100% normal time flow because objects are confined to the circle. 5:53 *Speed of Light* - The speed of light is fundamental - it is the speed all objects move at in space-time when considering both space and time. It is a universal constant. 6:20 *Speed of Objects* - Objects cannot exceed the speed of light because they always move at the speed of light in space-time. What changes is how their speed is distributed between space and time. Slow objects give more speed to time, fast ones like light give it all to space. 8:15 *Antimatter* - The lower part of the circle corresponds to objects going backwards in time. This provides a basis to postulate the existence of antimatter particles. 9:23 *General Relativity* - In general relativity, gravity is the curvature of space-time which converts temporal motion to spatial motion. Near black holes, an object's circle becomes smaller until at the event horizon it has no room left for motion. From a distance, objects appear frozen at a black hole's surface.

[@MichaelLloydMobile]

Fascinating. This is the best explanation I've heard of space-time. Outstanding!

[@karlsjostedt8415]

No explanation at all IMO. Just a step by step of conclusions, no explanations for any of the conclusions... Edit: he lists what we can expect to observe with no explanations as to why...

[@macysondheim]

Heard way better explications than this. Wasn’t impressed…

[@helifynoe9930]

If he would have continued onward and added length scalars to the graph, he could have shown how to derive the SR equations from it, as did I in my videos 8 years ago. Sadly, over the years, they don't get much attention.

[@mr.objective6936]

Macy - can you reply with links to those “better” videos ? But if this is one of those feeds that shadow bans posts with links (you can see it but no one else can), can you just describe the link ?

[@babayega_]

​@@mr.objective6936 the gentleman above you who commented has a 9 part series that explain things very well.

[@henrytjernlund]

Cop: Do you know how fast you were going? Driver: Yes, the speed of light. like I always do.

[@alwaysdisputin9930]

Cop: Do you know how fast you were going in the spatial dimensions? Driver: yep 30 mph* *relative to a car going 130 mph in the same direction

[@vodyaoriginal8543]

Pay attention, bro - u never were or will be going with c, until u find universe with no gravity.

[@tmst2199]

In relation to the fixed stars?

[@DPedroBoh]

The same as you, officer, the speed of light. Haha, we both laughed, he fined me and took my driver's license.

[@tonymurphy2624]

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

[@pitts8rh]

Every one of your videos that I've seen to date has filled gaps in my understanding of special and general relativity. There is something genuinely unique about your presentation and pacing that carries the viewer through every incremental step of the thought processes that others often assume are obvious and skip over or don't explain because they don't entirely grasp themselves. I find the animations and narrative to be spot-on, and I am looking forward to watching all of your presentations. Thank you for the immense effort that it takes to produce these.

[@darthnihilus511]

Absolutely the best description of space-time lightspeed and gravity I have ever seen.👍

[@karlsjostedt8415]

Description is an apt word because there is no explanation, just a list of what to expect according to what we know.

[@bigpompano1659]

Best visual representation of relativity I’ve yet to come across. SpaceTime could take a few notes

[@tim40gabby25]

Complimentary

[@AZ-bm3ki]

I am genuinely grateful for this channel. No other channel comes close in explaining complicated scientific phenomena with such clarity

[@-Pexy]

Definitely my favorite physics video. For literal ages I've been trying to understand the concept that everything moves at the speed of light, and I just understood it with no problem in some random 11 minute video. Absolutely insane, amazing content, I hope I see more videos like these.

[@solaris867]

Everthing do not move at the speed of light,

[@howaretherenousernamesleft]

@@solaris867 what are you talking about

[@aarondyer.pianist]

This video was so brief, so clear, that it passed into the bottom half of the circle and seemed to be false.

[@damianmedina8888]

Honesty I feel I could create my own time machine from all the knowledge in your videos, simple the best.

[@BD-np6bv]

This is why people believe conspiracy theories and are easily brainwashed. LoL

[@Shaunmcdonogh-shaunsurfing]

Can’t wait to binge watch this entire channel. Keep it going!

[@ScienceClicEN]

Thanks ! Hope you'll like future videos

[@DunkelStern]

You need to be writing on your videos the sountracks ))

[@tophater04]

That's what I been doing the last couple of days.

[@ViciousViscount]

That's what I already did. It's a good channel yo.

[@MrBendybruce]

The only thing that makes me sad about this channel is if I post a link to it on my fb feed it might get 1 like but if I post a picture of a cat using a human toilet it will get hundreds. Social Media is where curiosity and brains go to die..

[@hdthor]

I literally weeped when watching this. It’s so beautifully done and so incredibly easy to understand. I feel like Algernon in Flowers for Algernon when he finally understands things. Bravo, sir.

[@guyedwards22]

That last bit about the spacetime interval's distribution contracting down to nothing at the surface of a black hole sent shivers down my spine. I've been very familiar with interpretations of hypothetical phenomena surrounding black holes for years, the apparent "freezing" of an object falling in being one of the first I learned about. That connection with how spacetime curvature affects the spacetime interval was just perfect, meant to be, and makes so so much sense. The universe is utterly alien and insane.

[@sandre_sandre]

Brace yourself then: kzbin.info/www/bejne/aqO3p2ytq9uUqpo and kzbin.info/www/bejne/Z2jXdpqVqrl5laM for the VR version!

[@-_Nuke_-]

That's because a black hole is literally the edge of the Universe. One its edges, because it can have infinite of them.

[@romanski5811]

Does the circle contracting near massive objects mean that the maximum temporal and spatial speed of that object is decreasing?

[@TheToffeyman]

Man i predict that this channel is going to go viral pretty soon, there's no way an explanation like this one will go unnoticed forever!

[@24emerald]

I know right? ... best one I've ever seen too.

[@ramsesrameez5430]

Kareem who...??

[@TheRainHarvester]

You may really like a 2 min video I made, "the physical reason time slows at the speed of light". I've never seen an explanation like it.

[@khankbar]

No. Simply because his voice is monotonic and boring. The content is good, the delivery is subpar.

[@i7Qp4rQ]

No, people are lazy and seek pleasures.

[@alexy93]

i have seen vast amount of videos about this subject, but never gotten a more clearer explanation than this video. congratulations and thank you.

[@gregorygrandjean2895]

Nice, now all the world will be able to profit of the quality and the teaching of this channel !

[@ScienceClicEN]

Haha thanks ;)

[@ossiedunstan4419]

This channel is not a science channel it is pseudo science channel devoted to shitting on science and scientific method. If he continues I will be getting this channel banned in my country for promoting. wikki is not a got to site for scientist's , it is the go to a site for imbeciles who cant read scientific papers. Wikki is where religion's go , flat earthers , ufologist, alien abductor's, because wikki has no truth filter. When I want science I go to a places that aCTAULLY EMPLOY SCEINTISTS NOT A FUCKIGN WEBLPAGE WHERE ANY ONE CAN MAKE CHANGES TO ANYTHING. Places like SETI. perimeter , etc etc. I only come to pseudo scientific sites like this to object to the child abuse they are willing committing.

[@gregorygrandjean2895]

@@ossiedunstan4419 ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⣠⣶⡾⠏⠉⠙⠳⢦⡀⠀⠀⠀⢠⠞⠉⠙⠲⡀⠀ ⠀⠀⠀⣴⠿⠏⠀⠀⠀⠀⠀⠀⢳⡀⠀⡏⠀⠀⠀⠀⠀⢷ ⠀⠀⢠⣟⣋⡀⢀⣀⣀⡀⠀⣀⡀⣧⠀⢸⠀⠀⠀⠀⠀ ⡇ ⠀⠀⢸⣯⡭⠁⠸⣛⣟⠆⡴⣻⡲⣿⠀⣸⠀⠀OK⠀ ⡇ ⠀⠀⣟⣿⡭⠀⠀⠀⠀⠀⢱⠀⠀⣿⠀⢹⠀⠀⠀⠀⠀ ⡇ ⠀⠀⠙⢿⣯⠄⠀⠀⠀⢀⡀⠀⠀⡿⠀⠀⡇⠀⠀⠀⠀⡼ ⠀⠀⠀⠀⠹⣶⠆⠀⠀⠀⠀⠀⡴⠃⠀⠀⠘⠤⣄⣠⠞⠀ ⠀⠀⠀⠀⠀⢸⣷⡦⢤⡤⢤⣞⣁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⢀⣤⣴⣿⣏⠁⠀⠀⠸⣏⢯⣷⣖⣦⡀⠀⠀⠀⠀⠀⠀ ⢀⣾⣽⣿⣿⣿⣿⠛⢲⣶⣾⢉⡷⣿⣿⠵⣿⠀⠀⠀⠀⠀⠀ ⣼⣿⠍⠉⣿⡭⠉⠙⢺⣇⣼⡏⠀⠀⠀⣄⢸⠀⠀⠀⠀⠀⠀ ⣿⣿⣧⣀⣿.........⣀⣰⣏⣘⣆⣀⠀⠀

[@larsalfredhenrikstahlin8012]

@@ossiedunstan4419 Cool story bro

[@ascaniosobrero]

@@ossiedunstan4419 Which country is yours? Atlantis? Mu?

[@gamalipi]

This is by far the best video i have seen about relativity. Understanding it was an amazing experience and through visuals and crystal clear explanations, its hard not to grasp the idea that A. Einsteind left us. Thank you so much

[@new-knowledge8040]

Plenty of folk seem to hate my relativity YT videos. The idea was to show how just about any Joe Blow can discover SR. You just have to analyze "Motion" to determine what it is that is required to make motion possible. Before you know it, you end up independently deriving the SR mathematical equations. I'm a high school dropout, and in turn I had no physics background education at all, but I managed to do it. But some dingbats say that I am just bragging, and thus they miss the whole point of the video. It's about thinking in an independent manner. Granted, I did achieve this after being in a semi-coma for eight years. The semi-coma was due to me having a severe case of hypoglycemia. Those years really sucked. I could no longer spell my brothers name, and if you put 3 med pills in my hand, I could not tell you how many were there, all this was due to me no longer being able to recognize quantities greater than two. I no longer knew which was my right hand nor which was the left, and I did not have a clue which hand held the fork and which hand held the knife, and so forth. The automatic eye focusing no longer worked, and my pupils took up to 2 hours to respond to a change in light intensity. I could still type, but slowly, and only do so with one finger, since I no longer could coordinate and control both the left and right hands simultaneously. And the list goes on and on and on..... Anyhow... .......

[@xolaniholomisa841]

That whole idea about all objects traveling at the speed of light and only distribution their motion to space or time blew my mind! I could never get my head around why or how we came to have ‘c’ Thanks and keep up the great work!

[@lorenzoh.6571]

We should all run as fast as sonic to extend our lives lol

[@ebaderman]

Lorenzo Halevy no point becaus to us it would fee exactly the same

[@kliersheed]

@@ebaderman well if you are fast enough you are slowed down compared to your surroundings so they could cum up with new inventions to extend your life, so he wasnt wrong but probably didnt mean that :D

[@Mavrik9000]

0:05 *Introduction* - The expansion of the universe can accelerate objects faster than the speed of light, this is not true movement. It is due to the underlying expansion of space itself. 0:51 *Special Relativity* - Special relativity shows that as an object's speed increases, its time slows down compared to a stationary observer's time. At the speed of light, time would stop. However, one cannot go faster than light or go backward in time by going faster than light. There is a curve connecting speed and time, not a straight line. 3:37 *The Circle* - The curve connecting speed and time is a quarter circle. All objects in the universe lie on this curve. Negative speed means movement in the opposite direction. It is impossible to go beyond the speed of light or 100% normal time flow because objects are confined to the circle. 5:53 *Speed of Light* - The speed of light is fundamental - it is the speed all objects move in space-time when considering both space and time. It is a universal constant. 6:20 *Speed of Objects* - Objects cannot exceed the speed of light because they always move at the speed of light in space-time. What changes is how their speed is distributed between space and time in a tradeoff fashion. Slow objects give more of their "speed" to time, fast ones like light have all their "speed" as movement through space and none to time. 8:15 *Antimatter* - The lower part of the circle corresponds to objects going backward in time. This provides a basis to postulate the existence of antimatter particles. 9:23 *General Relativity* - In general relativity, gravity is the curvature of space-time which converts temporal motion to spatial motion. Near black holes, an object's circle becomes smaller until at the event horizon it has no room left for motion. From a distance, objects appear frozen at a black hole's surface.

[@fstkpfls]

This channel is mind-blowing. I've watched a lot of videos about relativity and spacetime, and i just accepted that I couldn't understand it without getting into the mathematics of it, but the models you're using are so intuitive and fit perfectly into what I had learned so far. How is this the first time I'm seeing this circle?

[@Deciheximal]

Because it's not a circle. The video maker abuses the shape for the purposes of making an attractive video. At best, it's a rounded square. Google graph speed of light vs speed of time, you'll see a rounded corner shape graph, which you can then mentally mirror twice over into the "circle" the video maker is arguing for.

[@fstkpfls]

@@Deciheximal Thanks for the tip, I know what you mean. The trade-off between the two physical quantities doesn't seem to be linear, though I wonder why.

[@Deciheximal]

@@fstkpfls The author cites special geometry to justify the circle shape (but presented it as far simpler than that.) I'm sure the math is fine.

[@Accell_Auto]

@@Deciheximal Is this just the video maker's theory and not recognized by academia?

[@maxprofane]

@@Deciheximal This is not correct.

[@GJ-GamingJunkie]

Your videos are insanely clear, to the point, well worded and easy to understand. For over 10 years I've been researching relativity, time, space, quantum mechanics, physics etc etc, just for fun because I absolutely love the subject. I've always struggled to visualise gravity in relation to time and space but after watching a couple if your videos its literally just clicked for me... clear as day! How on earth have I only just found this channel! I feel a binge watch marathon coming on haha. Keep up the good work!

[@OroborOSX11]

Ehhhh another modern physics hobbyist. Same situation here. I love learning about all this stuff, and this channel is an astounding resource.

[@dylandutson1626]

As a person who doesn't actually often comment on YT videos, I'm going to echo some of the comments here. I have been learning physics on my own for about a year now and this is the most amazing video I have seen yet. And it's not even close. There were moments that were so illuminating as to be beautiful that made me emotional. This was a gift. Thank you.

[@francoferro1625]

This was one of the best videos I have ever watched 🤯

[@ris3326]

-Can we travel at the speed of light? -Wrong question. Can we not to?

[@Will-be-free]

All we have to do to travel really fast is to stop time. Now I'm just waiting for the battery in my watch to run out. Only problem is that when you are waiting for something, it takes an eternity before it happens.

[@solapowsj25]

What happens at warp speed at near the speed of light is an interesting matter by itself.

[@sheetzTime]

@@solapowsj25 At speed of light , interesting or not - there is no/infinite "matter"

[@wailer27]

just get back to the kitchen, fiona

[@solapowsj25]

@@sheetzTime Warp speed is slower than speed of light. Warp is phenomenon in space related to standing waves before and after the craft at very high speeds. The laser craft, photon sail, and ion engine crafts would have to travel in warp space because they go very very fast ⚡⚡⚡⚡.

[@MehrdadParthian]

So we all, at all times have the speed of light, but when we want to move in space, we convert our temporal time into special time when in the beginning all of our speed was stored in temporal time. This is so amazing to understand. Thank you for this amazing and easy to learn video !

[@Doct0rLekter]

Indeed! It’s also good to understand the relativity part of this equation though: this is only how things are relative to a given observer. Our positive spacetime movement, for example, would appear to be negative relative to an antimatter version of us. It boggles the mind how complex this can get but I’m blown away by how simple this video made it seem.

[@-_Nuke_-]

Yes its brilliant!

[@dennis-o]

​@@Doct0rLekter​, you wrote “Our positive spacetime movement, for example, would appear to be negative relative to an antimatter version of us”. This is not quite correct. If your antimatter twin is at spatial rest wrt point A and you are in positive spatial movement wrt point A, your twin will actually see your spatial movement as positive. Temporal movement is where things will be different. Your antimatter twin will see you as moving in the temporal direction opposite to to their own.

[@djnone8137]

​@@dennis-o your antimatter twin twin will only see both you moving or not moving but it takes an observation to display such decision.

[@fanatamon]

And Karens convert their time into complaining. What a waste.

[@Sunkan2000]

Ive watched a lot of videos about space time as well as studied it for years in school. This video still gave me new insights, thank you!

[@siroggak]

Oh my god, these videos are so awesome! Why is youtube only now recommending them to me?

[@helmutalexanderrubiowilson6835]

You are a genius teacher.. this concept is so counter intuitive and you explained it very clear. You deserve tons of followers. Keep going fantastic job.

[@jasonsebring3983]

Ok, I'm now addicted to this channel. Bravo. Another aspect is the mesmerizing/hypnotic music.

[@dragonemperor5775]

It's been 2 years since this video is uploaded. Why haven't I seen this before?

[@AddisMultimedia]

Proof that google's a.i algorithm is still static. Otherwise people like us would have had seen it the day it came out. Is that even possible? Heck I'm still thankful that I found this today just like you. Congrats and happy marathon! 😁

[@Sttuey]

This has just popped into my suggestions today also, yet I watch this type of content very frequently - better late than never I guess!

[@afonsodeportugal]

@Dragon Emperor Because videos of kittens move much faster through KZbin space than videos with physics. In the KZbin universe, kittens are the photons!

[@Onimirare]

trillions of videos are posted every second, how do you expect to watch them all?

[@freenational]

@@AddisMultimedia, could it be that you turned "do not track" on?

[@jerrypolverino6025]

I understood spacetime before I watched this video, but this is one of the most simple, concise and simple explanations I have witnessed. Well done. I just subscribed.

[@amedeofilippi6336]

Outstanding lesson about the true meaning of motion in space time.

[@bondy86]

Honestly the best astrophysics videos I've seen on KZbin. So well presented, scripted, paced and graphically designed to allow steady digestion of the information. Please keep it up 👍

[@_agent47_]

Time is the speed at which an object moves at rest (as measured in the 3 dimensions of space we can observe). That realization blew my mind!

[@b.bjohnson135]

Highly intuitive! The illustrations are very fitting and fascinating. Top of the class I bet. 👏

[@artdonovandesign]

Narrator: "To Conclude"... Wait! Lemme' re-watch the entire episode a few dozen times.

[@russellsantana]

There are a number of high-quality channels on KZbin. This has to be one of the top 5, in my opinion. Phenomenal explanations.

[@4shadow2]

For once youtube recommended a good channel

[@NerdMusician]

Your channel has the best, most visual, explanations. I'm mind blown.

[@ScienceClicEN]

Ahah thank you very much !

[@bennybooboobear3940]

@@treyt6474 I’m gonna comment to help you out!

[@bennybooboobear3940]

@@treyt6474 I think it’s because time completely just stops at the horizon.

[@giulialosi4805]

Guys you are amazing! I am binge watching videos about relativity, time dilation, light etc since I saw Interstellar for the second time, it is becoming a sort of mania, and I can't find anything more adamant than your explanation. You make everything incredibly comprehensible, almost natural, and please consider that I am not an English native speaker. Also, I find it crucial that you leave a bunch of seconds of silence after each concept to digest each piece of information before getting to the next one, almost nobody does it.

[@MonkeyMan12121]

Wow, just amazing. Nothing else to say, just amazing.

[@Paradoxwhirl]

Thank you, that was awesome. You've even included the holographic principle at the end with the information being contained around the horizon. Subscribed :)

[@ScienceClicEN]

Thanks !

[@kenn743]

"Let's make a world in which we go to other worlds." amazing video thanks

[@Tony-be8rf]

Nice! Translating your videos is a great idea! Keep it up

[@ScienceClicEN]

Thank you very much ;)

[@bayloch]

What a great video! I've never seen/heard space-time described in such a coherent (visually-friendly) way. Good job!

[@mythic_snake]

This is the first time I've heard it explained like this. I did not know that anti-matter was simply matter traveling backwards in time. Very fascinating!

[@markoprskalo6127]

That is sick theory I thought about that

[@AverageAlien]

It isn't. Anti matter is not matter travelling backwards through time, but it can be looked at that way

[@someoneinmyhead]

This is the most insightful explanation of spacetime. And I've seen many. Same for the fundamental speed. Great job!

[@MichiganUSASingaporeSEAsia]

My head is spinning now. I thought I mastered these concepts. It’s similar to what they are saying at the Western Michigan University school of engineering and aviation departments...

This video connects many dots. I love coming back to it, periodically.

[@feynstein1004]

9:55 Wow, I just had my mind blown 😮 I'd never thought of gravity that way. Truly amazing stuff. I can't wait for more.

[@PieterPatrick]

I'm sure you also want to see this: kzbin.info/www/bejne/fGazl52phcl1sMk Channel "The Science Asylum" about gravity will also blows your mind. :-)

[@feynstein1004]

@@PieterPatrick Hey crazy. I'm subscribed to Nick already ;)

[@PieterPatrick]

@@feynstein1004 Ofcourse you are... lol Sorry for that. :-)

[@feynstein1004]

@@PieterPatrick It's okay. Great minds do think alike :D

[@ibrenecario7357]

Thank you. I never seen this explained like this. I wonder what the channel did to suddenly get into my recommendation (and alot of other people judging from comments)

[@davidbrown8763]

To me, none of this makes sense. The claim seems to be that time slows down as speed increases. How can this possibly be proven when SPEED IS A FUNCTION OF TIME? In other words, you can only know how fast an object is travelling, relative to anything else, by assuming that the flow of time is constant for all objects. Again, since speed is a function of time, it makes no sense to speak of the speed of time. since its own "speed" can only be measured as a function of itself.

[@anonymousperson9052]

@@davidbrown8763 🤦

[@autobot3925]

@@davidbrown8763 This whole explanation starts with the initial assumption that the observer is at rest, ie, has no velocity. Here, Speed any how is rate of displacement in a fixed amount of time. As in, a photon travels way farther than an alpha particle in a second

[@512TheWolf512]

This is THE way everyone in the world should be taught general relativity. It is outrageous that something this fundamental and this easy to understand is something you need to consciously seek out

[@416-t7v]

i found your channel from reddit and i don’t regret..

[@ScienceClicEN]

Glad you like it! welcome :)

[@PNW_Marxist]

Thank you for this, that was a completely different way of wrapping my head around special relativity and it's making some things click in a far more intuitive manner than before.

[@kliersheed]

same. i still couldnt explain this to anyone ,but my intuition says it makes sense :D (comparing it with other videos i watched and comments i read) only the antimatter thing is still a bit "meh".

[@korras21]

By far the most important explanation of space-time and speed of light dependence I have ever come across.

[@ExileLuciola]

Part of this is misleading. Anti-particles don't move backwards in time ... we see positrons all the time and they travel in a way predictable with forward movement of time and they are anti-electrons or the anti-matter version of electrons; such as in beta decay.

[@Hello-qg4yk]

Yeah. Only mistake I noticed too

[@tomhepz]

It's not completely wrong unless that's what you were implying, an electron moving backward in time is equivelant to a positron physics.stackexchange.com/questions/391/is-anti-matter-matter-going-backwards-in-time

[@ScienceClicEN]

Yes, it's mathematically equivalent to say rather that the antiparticle has opposite charge, or that it's an ordinary particle moving backwards through time. It can seem weird at first, but it's actually very elegant to think about. Why would every particle have an antiparticle with all same properties except opposite charge ? It's more satisfactory to just allow particles to go back in time, and thus you don't need to introduce another form of matter. If you want the mathematical reason for this equivalence, it comes from the fact that particles with electric charge in quantum field theory are described as waves of complex numbers. These waves can either be of the form : exp(it), or exp(-it). Now you have two ways of interpreting this : you can say that your particles have either +i or -i (complex conjugate), which corresponds to saying that you have opposite charges, or you can say that your particles can have either +t or -t, which corresponds to saying that they can go forwards or backwards in time

[@Deciheximal]

@@Hello-qg4yk Did you notice that the circle shape was wrong? It would be a rounded square. Google graph speed of light vs speed of time, and you'll see what I'm talking about.

[@AverageAlien]

​@@Deciheximalhis graph isn't wrong you just don't understand graphs

[@darkknight097]

Man I love these videos. They give me a completely new level of understanding of concepts that i thought I had an idea of and ties them all together nicely.

[@stylersimon1]

You make Physics into a story that is worth listening to. Unbelieveable. Really.

[@SumeetKumarHC]

This video was one of the best science video ever. You are a true genius 👏

[@MrMultiSingularity]

I love the concept that everything is moving at the speed of light. I've never heard this presented before and it really helps answer quite a few questions for me. I still struggle with the idea of movement through space in general though. For from any given perspective movement is still unto itself. Meaning that movement through space can really only be perceived when in contrast with some other object in space. If two object were moving away from each other at half the speed of light, how do we know which one is really moving? Or are they both moving at 25% the speed of light creating the perception of half the speed of light. Couldn't both objects make the claim that the other object is the one moving away from them at said speed and that they themselves are still. So in the example you gave with time slowing down according to the object moving very quickly, wouldn't that slow down in time be only perceivable again through comparison with the slow moving object? From the perspective of the ship, would not time still appear to be moving at a regular speed? And then how would that work from the reversed idea, whereas the ship would consider itself to not be moving at all and would look at the object it was originally moving away from to be the one that is then moving away from it at a very high speed. How would one even be able to tell which object is actually the one going fast in the void of space? I feel this concept very accurately embodies the 3 point problem. In the void of space everything is relative to something else, but is still unto itself. Another way to think about it is, Is Andromeda moving towards the Milky Way, or is the Milky Way moving towards Andromeda? I mean the only really accurate way to say it is that the two Galaxies are moving towards each other. Now Hypothetically speaking, let's say the two galaxies were closing in on each other at the speed of light. Is one moving at the speed of light or the other? Does it matter? They would not be able to accelerate towards each other any faster than that and Lorentz transformations would assure to it. The same would go if the objects were moving away from each other in the same scenario. You now have me completely puzzled about how the time dilation would occur between those two systems in said example. If there was a clock on a planet in Andromeda, and one on Earth, would they relate to each other at all. If they somehow were synchronized, would the speed that the galaxies moved towards each other effect those times at all? Just like the rocket example from earlier, how would one even tell which is moving towards the other at what speed. Perhaps it is only revolutionary speed that actually creates time dilation, since revolutionary speed can pretty accurately be measured relatively. Perhaps space/time is not a all pervasive web as we currently think of itit, but kind of a thing that mass itself carries with it. Every bit of mass is like a little bubble of space time that's pull is relative to it's amount? I am kind of just thinking out loud here, feel free to give me any information you feel may be relevant. Thank you!

[@Hello-qg4yk]

I really like this idea!

[@antonystringfellow5152]

The simple answer is, it's all relative... speed and time. Even position in the Universe. For example, if you use observation to determine your position in the Universe, you will find that you are dead centre, with the edge being approx 13.7 billion light years away. Someone in a galaxy 10 billion light years away, performing the same observations, will find that they are dead centre of the Universe too. Which one is correct? I would say they're equally correct or, more accurately ..... equally wrong. I don't believe the Universe has an edge and, if it doesn't have an edge, it can't have a centre. Your position in the Universe is relative/subjective. Equally, your position in time and space is subjective. Hope that helps.

[@fuseteam]

yes why from our point of view the time of a fast moving object is slow, from the point of view of the fast moving object time flows 'normally' and both observations are correct, that two of the postulates of relativity: there is no preferred observer both observers are correct but we can go further: the speed of light is the same for all observers you read right *all* observers whether you look at it from our point of view or from the point of view of a fast moving object light always travels at the speed of light

[@duprie37]

We're always moving at the speed of causality. At rest we're moving through time at the speed of light per second per second. In a car at 80 km/h we're moving ever so slightly less through time and more through space so that our total speed still equals causality. A photon moves through space at the speed of light per second and doesn't move through time at all so that it also still travels at the speed of causality.

[@cyrusg8402]

I think this video might help kzbin.info/www/bejne/poXRZ3itncdlbc0 And this playlist kzbin.info/aero/PLsPUh22kYmNCLrXgf8e6nC_xEzxdx4nmY

[@snoozieboi]

So I come to these videos regularly, not to understand, but to marvel. A photon travelling at the speed of light essentially experiences not time(?). Does it then even move? Or does each position for the photon just become a static "image" of the world around it? I think I'll just go back to drinking coffee.

[@Observa_]

The photon moves through space at the speed of light. We see the photon as moving through time because time is passing for us while the photon is moving through space. But from the photons point of view, no time has passed and it has only moved through space. For the photon it seems that it has traveled it's whole path through the universe at the same moment in time. It's internal clock is stopped. But for us we see the photon as moving through time because our time is passing and the photon exists in multiple of our time frames. So what is the same moment for the photon can be billions of years for us. It's all a matter of perspective. Hope this helps :)

[@REinCoat_Records]

Coffee for the countless late nights trying to theorise this concept and it's possibilities through? I know I am😂

[@otaku-chan4888]

Actually, high speeds doesn't slow *time* down. It only *makes events take longer to happen in time.* I know this sounds like the same thing, but the truth is- *we can't measure time.* All we measure are events that happen in time. From our childhood, we build an intuition of 'time' by using clocks, guesstimating how long a second is, and gain a concept of 'long times' and 'short times'. For example, let's take the simplest clock we can imagine: a photon clock. We can say time dilation takes place when outside observers say fast-moving people's clocks _have photons that take longer to tick._ That's an event that's taking longer. That doesn't mean *time slowed down.* Rather, we could say that when 'time dilation' occurs, _our perception of events warps, and makes it appear to take longer._ in my opinion, photons do have 'time.' The only thing that could make a photon stop experiencing time is when *a photon no longer exists.* However, _no events occur for a photon._

[@AverageAlien]

The photon does not experience anything, from its perspective, the universe is flattened so much that the photon exists at the beginning and end of its journey simultaneously

[@ravishankar2180]

wtf did i just watch? it completely blew my mind. such a nice explanation of S&T.

[@First.nameLastname]

its really the speed of causality. light is just something we can measure easily.

[@GoogleUserX]

Exactly !!! Causality IS the true fabric of the Universe !!!

[@lloydtucker5647]

🤔

[@gol.drodger5261]

Relatively* easy.

[@furkancolak3702]

Causality, this word has so deep meaning. Causality doesnt have a speed. There isnt particulary limit distance between result and reason. I mean we just define causality as a two point, point of reason after point of result. So isnt that wrong to think speed of causality with this definition?

[@First.nameLastname]

@@furkancolak3702 uhm, no. Causality in terms of space has a speed limit. 299,792,458 m/s. this is precisely what I mean. We can disagree, that's fine. But this is the meaning of my words. I'm not sure what "point of reason" and "point of result" means in your terminology. Things can not cause faster than 299,792,458 m/s. kzbin.info/www/bejne/o6S5pnZ7qJ2MmtE

[@paymansalehishafa6884]

Wow, don’t ever stop educating. You’re simply the best out there.

[@Tristan-uf5hu]

J’adore tes vidéos et la physique. J’apprend énormément de choses mais je suis au lycée , je ne suis pa tres bon en anglais et je sais que j’aurai besoin de l’anglais plus tard du coup je regarde des vidéos de science ( sujet qui me passionne ce qui me force a en regarder ) en Anglais et mon niveau monte très vite. Merci beaucoup je les regardent en boucle ce qui me fait l’oreille et le vocabulaire vu que je connais les versions françaises ! Encore merci mes parents sont enfin heureux que je soit sur KZbin mdr...

[@ScienceClicEN]

Merci beaucoup pour ce commentaire, ou plutôt... Thanks a lot for this message, that's a very good idea. I'm glad you like the videos and hope it will help you improve your English :)

[@jarbuyer]

mind blown...... speech less.................................................

[@bamf6603]

how are we moving speed of light? Only photons with no mass can move with the speed of light. And how do we move with speed of light if we have mass?

[@Admiralty86]

Mind absolutely blown. Lot's of big puzzle pieces connecting hard.

[@ryandemanuele7612]

So well explained! It would be interesting to explore why C is what it is and if C could be derived mathematically without real life measurements

[@viktorLOL123465]

Why is this making perfect sense?!

[@AverageAlien]

everything clicks now

[@adamlea6339]

This is a very good way of visualising spatial and temporal speed. What happens when you speed up spatially is that on the space-time graph, you are moving your motion vector around the quarter circle without changing its magnitude, and it takes an energy input to do this. What the graph doesn't show is that the amount of energy required to rotate the vector of motion towards the horizontal (i.e. purely in the spatial direction) asymptotically increases to infinity.

[@augijyotbali2131]

You know what ! I LOVE YOU FOR MAKING THIS MASTERPIECE!

[@tamaldatta8520]

Can you relate the light cone with this circle of causality ? If you can then please tell me, it'll be very helpful. Thanks.

[@8L8_Ash]

“Entropy is entirely distributed along its surface” Is it because of all the objects that keep falling/“resting” on the black-hole’s surface?

[@ZeroSpawn]

Right!? when he said this, my mind farted. So the reason why galactic centers are so bright is because of the consumed stars are still imprinted on the surface of the black hole? 🕳️

[@jonahrumsey2247]

this channel always gives me so much more insight and understanding than any other channel. criminally underrated!

[@kateiry4719]

"We all move at the Speed of Light" sounds like a catchy line of lyric from 2012

[@fredneecher1746]

"We all move at the speed of love" - Brian, from Family Guy

[@jd35711]

we all move at the speed of light in a yellow submarine

[@alibenam2766]

By far, the most understandable and accurate illustration of time dilation. Kudos to you 👍👍

[@godsofentropy]

This is one of the most important and opening-mind films I saw in my life. Thank you.

[@actuallyawful]

Great presentation, but a photon isn't a null geodesic in reality: it's a quanta with internal degrees of freedom which change in time, and hence can be used as a clock, such as polarization

[@ScienceClicEN]

Indeed, or we can use the wavelength as an affine parameter. However even in QFT the 4-momentum vector of the photon is null so the standard definition of proper time does not apply.

[@benYaakov]

@@ScienceClicEN photon lies on the horizontal on the space time graph

[@aemic0pl]

Like the video but there's one big mistake made here - antimatter - it couldn't go back in time because it's only difference to normal matter is opposite charge - to go back in time antimatter should have a property of negative mass which it doesn't have as it has positive mass.

[@frankkolmann4801]

Not so. A negative times a negative is a positive. Simply moving matter backwards in time is antimatter.

[@cabanford]

Damn. This is my new most favoritest every channel. Epic.❤

[@Nazar_38]

Bonne idée de faire traduire tes vidéos ! Avec de la chance tu fera une percée chez cette communauté :D

[@ScienceClicEN]

Thanks !

[@snyseb]

Il a une grosse voix ton traducteur

[@exoplanet11]

Excellent video. As one who teaches special relativity, it is nice to see the graph shown at 3:00 (which must be distinguished from a spacetime diagram) relating motion through time. The notion of antimatter as particles traveling backward in time (an essential aspect of Feynman diagrams) is presented well as particles on the lower part of the circle. However the question arises: why is ELECTRIC CHARGE the property that must be reversed in order to place a particle on the opposite side of the fundamental graph representing motion through space-time? Motion through spacetime (as shown in that graph) seems to be a fundamental aspect of any particle, more fundamental than any of its individual characteristics through which it feels forces (eg. charge, mass, nuclear 'color charge', etc.)

[@TakuTJuly]

"The more you study relativity, the less you know" - Me

[@suzukix3082]

Same

[@xyz-cv3dv]

What

[@TakuTJuly]

@Roger Loquitur I didn't under stand anything but.. Thanks for telling :)

[@sarthak8350]

True

[@Chicken_Little_Syndrome]

“Einstein's relativity work is a magnificent mathematical garb which fascinates, dazzles and makes people blind to the underlying errors. The theory is like a beggar clothed in purple whom ignorant people take for a king... its exponents are brilliant men but they are metaphysicists rather than scientists.” - Nikola Tesla “Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality.” - Nikola Tesla

[@TomtheMagician21]

This channel is so amazing I came to rewatch this video just because of how good it is at explaining special relativistic concepts. What would the graph look like if you included acceleration? Would it be able to explain the twins paradox too?

[@peanutbutter3578]

No wonder 5 minutes felt like forever as a child. You're closer to the earth cause you're short...

[@heyykenn9099]

Programmers of the universe: "What the.. How did they come up with this?"

[@monad_tcp]

programmers of the universe: fine, they calculated the universe's clock rate, it doesn't matter because the clock rate of the simulation is still slower than the real clock.

[@monad_tcp]

​@AmericanAndy I do think you can go back in time, but you get stuck in time-curves forever if you do that, because you lose causality with the rest of the universe, effect can indeed come before the cause if you have time-curve loops.

[@heyykenn9099]

@@monad_tcp So true, the clock of the simulation might only tick a second once a year in their own universe but we have no way of feeling it because the speed of the processes in our brain also move slow. it has become our reality

[@heyykenn9099]

@@monad_tcp it said that there will be no movement in either time or space if you are in a blackhole. If you associate a blackhole to any computer phenomenon, what would it be? a glitch? what could it be?

[@heyykenn9099]

another question, in the graph, when you go at the speed of light, time stops. But how can you go down the graph(go to the negative quadrant of time and go in the past?) if the graph is circular and theres no way passing the speed of light? what would be the force to enable us go down that graph

[@theadrum]

I've always liked to think of the speed of light as instead of speed of causation. At that speed no time passes to observers because you are time. The speed at which something 'happens'.

[@Robin.Tussin]

According to, who?

[@raykos4257]

Findings in quantum entanglement seem to contradict this idea.

[@zeiccia]

@@raykos4257 like what?

[@AminoJack]

Ive had an educated lay interest in physics for the past 25 years and this is literally the first time I've ever seen the concept of ths speed of light presented this way....quite literally just blew my mind.❤

[@WildLeghorn]

Science: Nothing can travel at the speed of light! Also Science: We all move at the speed of light. Me: Thank you for frying my brain 🙄

[@pascalcoole2725]

Think at it as a vector. like sine and cosine can represent a direction.

[@komnennos]

man, I'm not high enough for this

[@danielpalacios4848]

I was

[@herrunbekannt3822]

I am. And its awesome!

[@davidbrown8763]

To me, none of this makes sense. The claim seems to be that time slows down as speed increases. How can this possibly be proven when SPEED IS A FUNCTION OF TIME? In other words, you can only know how fast an object is travelling, relative to anything else, by assuming that the flow of time is constant for all objects. Again, since speed is a function of time, it makes no sense to speak of the speed of time. since its own "speed" can only be measured as a function of itself.

[@theobolt250]

@@davidbrown8763 They do it with clocks, like the guy in the video said. These clocks then be atom-clocks. One goes with/aboard the traveling thingy the other stays on terra firma. And... that already HAS BEEN DONE! So, proven fact.

[@davidbrown8763]

@@theobolt250 I disagree because the clock on the travelling "thingy" is subjected to forces every time the "thingy" accelerates - that is increases or decreases in speed and/or changes direction at constant or changing speed. Even though it is an atomic clock, I believe that these forces could destabilise the clock sufficiently to give very small (infinitesimal even) untrue readings versus the terra firma clock, which is not subjected to external destabilising forces. Hence the apparent difference in time readings.

[@jakubnovotny1010]

This is the most mind-blowing video I have seen in years, wow, thank you so much!

[@normg2242]

Love the uncluttered simplicity of your explanations, and also the unhurried way of narration, great stuff! But if you permit me to bring this up - I'm not sold on the lower part of the circle yet. I think our thinking loves to snap to the confines of completing geometric shapes when it comes to extending our theories by thinking it must be the same as the part we already discovered and can observe. I have the feeling that the lower part of the circle may actually have to be drawn through other dimensions before it returns, yes, even on a graph. Or it may not even connect at all. Please forgive me for this but somehow I think moving the arrow below the light speed axis on the circle graph does not serve any purpose in our quest to understand how spacetime behaves when going backwards. I'm not a scientist but this is my personal intuition...

[@Deciheximal]

It's a rounded square, not a circle. Google speed of light vs speed of time on a graph, you'll see what I'm talking about.

[@bjoernoeder]

What about the contrary: When do we experience 100% of time or when are we in complete stillstand?

[@ahmetakgun7709]

Since the earth is spinning around the sun, standing still in this world doesn't allow us to experience time 100%. Only an object in empty intergalactic space, away from the gravtional well of the solar system and the milkyway galaxy would know.

[@_inSight__]

It would probably age out of existence before you even realized it was there. That's probably what dark matter is.

[@Qball__]

@@ahmetakgun7709 But then again aren’t all atoms vibrating? So you can’t ever be completely still?

[@ahmetakgun7709]

@@Qball__ in an empty space where there is no light, heat or any other radiation the temperature drops to absolute zero (-273 C or 0 F) At that level even electrons stop spinning and atoms stop vibrating. Though, quantum fluctuations and other mysterious things happen.

[@Qball__]

@@ahmetakgun7709 I didn’t think absolute value was possible to achieve because I thought atoms would cease to exist if they completely stopped vibrating

[@varunahlawat9013]

This is by far the most important video I've ever seen in my life(going to pursue aerospace in USA this fall...).

[@squatcitygaming1726]

I've been watching youtube since it began. I have only ever subscribed to three channels, you just became that third channel. Truly, truly, brilliant! I'm going to binge watch your whole channel. F*ck netflix when you have this!

[@gustavoa8396]

that last step of the circle comtraction could be more explained, i felt lacking. i don't really know if i understood it

[@TheNasaDude]

My understanding is that space-time gets progressively distorted the closer you get to the event horizon. At the event horizon, you can only go straight down towards the black hole singularity. This is true for any point of the event horizon surface. The circle diagram is not drawn on paper, but on space-time. If you lay the diagram tangent to the event horizon, the circle becomes a point because you cannot move "laterally" both in space and time (you must go to the singularity). If you raise the diagram sheet away from the black hole (without changing the sheet orientation), the circle becomes less and less point like. If you stack many diagrams on the black hole, and look at a normal cross section of the plane stack, you find a shape resembling a funnel. This funnel defines the space time distortion provoked by the point of the event horizon chosen to begin the stack

[@winsontam6334]

@@TheNasaDude hmm... What about with a less extreme example? Like what does the circle look like with an apple in orbit vs the apple on the ground? From this video, I've been getting the idea that all objects are moving at c, but as different distributions of space and time... (ie - speed through spacetime) So how does gravity (or the curvature of space time) affect this circle or c?

[@TheNasaDude]

@@winsontam6334 the circle is not really a circle, but a 4 dimensional sphere. As you know, in relativity gravity IS the stretching of Spacetime. An apple on the ground will be forced to move solely through time with respect to earth. The circle of possible motion will be slightly stretched because of the gravitational influence of Earth. An apple in orbit around Earth will be moving slightly slower in time and at some spatial speed in a straight trajectory. The trajectory will appear as an ellipse, because spacetime is slightly warped around Earth. At the event horizon, you have 0 movement through space, because all your speed is attributed to time, in the "direction" of the singularity. One way physicists describe this, is "you can't avoid the singularity, in the same way you can't avoid tomorrow". Any energy you apply to try and escape, will not change the outcome. Again you must remember that the diagram, be it simplified as 1 spatial dimension and the time dimension, or complete with all 4 dimensions, is drawn on an entity (space-time) that is not fixed, perfect and immovable. It's a bit like drawing on a trampoline while in use. You can calculate Spacetime elasticity, and it's indeed quite stiff: you need a lot of mass in a very small volume to get noticeable effects.

[@winsontam6334]

@@TheNasaDude dude, gold star ⭐ if there was such a thing on here! Thanks man, I appreciate it!

[@SolidSiren]

The way I understand it: What is realized about a black hole is that once you reach the event horizon, or pass it rather, space and time become inverted. "Forward" toward the singularity becomes forward in time, instead of forward in space, and you cannot avoid it under any circumstance. Inside there, you are moving ONLY forward in time, and space sort of...expands outward in front of you, as time normally does. Outside the black hole, you were moving toward it, forward in space and forward in time. Once you're inside the horizon, these parameters switch. Forward, or toward the center, which seems like a spatial coordinate, is now forward in TIME. Because you are now experiencing all your movement in time, not space, you approach the middle as if space were time. And because you are barely moving in what was "space", the center seems to contract and be ever far from you. That is what the math tells us happens anyway. We dont know for certain.

[@skumar2096]

This explanation using a circle is simply the best for this complex subject

[@TheMakloy]

There is something I cannot clearly understand with relative speed : If I am on earth and see a spaceship going 99% of light speed relative to me, then my time will pass normally, but the clock I would see in their ship would be very slow, right ? Now, if I am on this spaceship and I look at earth, then earth speed would also be 99% of lightspeed relative to me, then the spaceship time would pass at normal speed, but the clock I see on earth from my spaceship would be very slow. Is that right ? In that case, if a spaceship travel at 99% lightspeed from earth and then come back who would have aged faster ? The people on spaceship or the people on earth?

[@ScienceClicEN]

That's a good question, it's actually called the "twins paradox" ! Indeed, if they are moving relative to each other with a constant speed / direction, both the earth and the spaceship see the other one evolving on slow motion. But as soon as the spaceship turns around in order to come back to the Earth, it is no longer following a geodesic path (it is no longer moving with the same speed / direction). Therefore, the fact that the spaceship turns around breaks the symmetry of the problem. The Earth is still in an inertial frame of reference, but not the spaceship, because it has changed its movement (it has accelerated). When it comes back, it's the people of the Earth which have aged faster.

[@matthewpichou]

@@ScienceClicEN What if the outgoing spaceship doesn't turn around but instead, reports the time on its clock to another spaceship heading back to earth at the same speed. The returning spaceship adds its own travel time to that reported by the outgoing spaceship. I'm pretty sure that the combined travel time of both spacecrafts is still less than the travel time observed on earth -with no acceleration involved. It seems to me that the gist of the answer is that the distance to the turnaround point is different for the spaceship observer and the earth observer because one of them is moving between the earth and the turnaround point at a significant fraction of the speed of light and the other (on earth) is not. The spaceship experiences length contraction of the distance to the turnaround relative to the distance the earth observer sees. The earth observer sees apparent time dilation of the spaceship's experience compared to his/her own. Two sides of the same coin?

[@nickhowatson4745]

Both age. Time increasingly moves slower around increasingly large mass. The faster you move the more massive you become. If you were somehow able to reach the speed of light 2 things would happen. 1 you would freeze in time. Your clock would freeze. 2. Your mass becomes infinite so you collapse into a blackhole. And thats if you survive the massive dose of gamma and xrays while approaching those speeds. At those speeds the cosmic microwave background radiation becomes so blue shifted that its no longer microwaves but extremely intense gamma rays.

[@alexalbertazzi6618]

@@nickhowatson4745 the faster you accelerate the more massive you become

[@keplergelotte7207]

Actually the travelling twin passes through less time because it has travelled through more space than it's stationary twin. Acceleration is not the reason for time dilation.

[@Bassotronics]

The photon still “sees” time because it’s affected by gravity. It’s not 0 but 0.000000001 as an example. Causality is faster than light and must be for light to even have a speed.

[@eponanope1869]

I dont think so, photons follow a straight line, and gravity curves the space over time. So, they dont need to "see" time for being affected by gravity.

[@SolidSiren]

The speed of light IS the speed of causality.

[@SolidSiren]

The only reason photons are affected by "gravity" is because spacetime is curved. The light is still doing its normal thing, just the spacetime is curved. Causality is not faster than light. The "speed of light" is the speed of causality. It is the maximum speed that is relevant. This video tried to show you that.

[@chinmaychandraunshuh]

beautiful video this was, thanks for this! I also have to say this, black holes really scare me out!

[@jialixx]

I run fast every day, that's why I age slowly. Proved!