We All Move At The Speed Of Light… Kind Of.

[@ScienceAsylum]

Compare news coverage from diverse sources around the world. Take advantage of their Holiday Sale sale to get 40% off unlimited access by going to: ground.news/scienceasylum. Sale ends December 31.

[@numbersix8919]

Thanks! I'd like to take some credit for suggesting this. It's one of my favorite concepts. But Shirley, this doesn't fit in with the Block Universe? One doesn't normally think of anything moving within the Block Universe.

[@danquaylesitsspeltpotatoe8307]

Also we all move faster than the speed of the light depending on the relativity! So why didnt go with this better video? 🤔

[@Seventh7Art]

Βro, the Greek τ is pronounced "taff" in Greek. That "tau" thing has a "u" that is not pronounced as "oo". It is a myth that it sounds like taoo. In reality it is pronounced like taf or tough...

[@numbersix8919]

@Seventh7Art Let's ask 10 physicists...

[@Seventh7Art]

@@numbersix8919 Physicists are not linguists. I am sure you know the difference. The same applies to the Greek letter π which is pronounced like a pie, when in reality it is like pee but with a short vowel sound. Greek letters can only be pronounced correctly, when you use the original Greek pronunciation. Anything else is a corrupted version. Δ which is known as Delta, in reality it is "Τhelta" where th does not sound like in "thesis" but like "they".

[@TheMarkArmy]

I feel so lucky to live in a time period where I can learn relativity from someone for free! You assume the watcher knows little but can explain it in such simple terms. I love your content so much, you are a gem to have on youtube.

[@ScienceAsylum]

Advice I received: "Don't underestimate your audience's intelligence, just their vocabulary." and I try to live by that as much as possible.

[@numbersix8919]

@@ScienceAsylum That's great advice for anyone.

[@cesarehipthenhopthenhip8377]

It's okay to be a little gem 😂

[@seanspartan2023]

One of the reasons I like this channel so much is the fact that complex ideas are explained in a simple way so you don't need much math or physics background to understand them.

[@taziefahmed9750]

dont forget the the friendly animations they the best to follow along

[@seanvermilion7256]

I'm in agreement with you! Math is a more precise way to express generalizations. Accuracy comes from how we define things, which can also be improved with math. I hope one day math can provide you with as much satisfaction as friendly explanations :)

[@chekote]

I’ve been arguing this for years. Now I can just point people to this video instead of explaining it poorly myself 🙏

[@brothermine2292]

You could also point people to a FermiLab youtube video posted about 6 years ago, titled "Why Can't You Go Faster Than Light?" And I think the PBS Space Time channel posted a video about this about a year or two ago. I'm going to post a comment soon that you might want to read.

[@new-knowledge8040]

Yes.. I called "c", the "c" magnitude of motion, rather than speed of motion. Many many years ago, I mentioned how even a high school dropout who knows nothing about physics, can still derive the Special Relativity(SR) equations if just able to recall a bit of math and a bit geometry, and taking this constant "c" magnitude into account. Nobody believed me. So about 10 years ago I jumped onto YT to prove my point.

[@diablo.the.cheater]

Yep same, when I first read about light speed years ago, this was also my understanding on what was happening, it is easier to imagine it as changing a ratio.

[@feynstein1004]

I had a thought about this recently. I tried to imagine what it would look like if something stopped moving through time. Let's say we have a box at rest. Even if it looks motionless, it's still moving through time because at one instant, it's there and at another instant, it's still there. But let's say it stopped moving through time. What would happen? One instant, it's there. The next, it isn't. And it's not like the box went somewhere else because that too would require motion through time. No, in this case, the box just up and disappears. It's literally erased from the universe, violating conservation of mass and energy, which isn't possible. Which is why everything must always be traveling through time, because otherwise conservation of mass/energy wouldn't be valid. It's also interesting how this line of thinking hints at the underlying connection between time and mass/energy conservation. Of course, we know it's really energy conservation that stems from time symmetry so it's kind of easy when we already know what to look for 😀

[@ScienceAsylum]

And it shouldn't be that surprising that energy is the time component of the 4-momentum 👍

[@richardwallis9374]

I thought an object that isn’t moving in time is moving at the speed of light? Can’t move faster but if none of your energy is in the time direction then it’s all in spatial. All C of it!

[@feynstein1004]

@@richardwallis9374 Interesting point. I hadn't thought of that 😄

[@Taigan_HSE]

I heard about this idea a few months back and, while I’m sure I don’t fully grasp all the subtleties, it’s the first picture of the universe that makes me *believe* nothing can go faster than the speed of light. I accepted it before but always with a “…but what if…” tacked on. But if the speed of light is the speed everything is going in 4-space, then nothing can go faster than C in 3-space because there’s no place for that extra velocity to come from.

[@ScienceAsylum]

*"Nothing can go faster than C in 3-space because there’s no place for that extra velocity to come from."* Exactly! 🤓

[@ballparkjebusite]

My son, 9, is gonna be so stoked there’s a new video! We watch these in bed at night before sleeping. Keep up the good work. (I’m excited too).

[@ScienceAsylum]

That's wonderful. Thanks for sharing!

[@talideon]

So essentially, everything always moves at the speed of causality through space-time, and if you want to move faster through the spatial dimensions, that necessarily means you move slower through time, otherwise causality would be violated.

[@Mysoi123]

7:03 Note that when he said "a loss in temporal speed," what he meant is that as the rock moves faster, the proper time of the rock (𝜏) passes more slowly. However, since we defined the temporal speed as dt/d𝜏, the denominator of the derivative becomes smaller as the rock moves faster. This implies that both dx/d𝜏 and dt/d𝜏 approach infinity as proper time passes more slowly. What he intended to convey is that more time passes for us than for the rock. As the rock approaches the speed of light, both dt/d𝜏 and dx/d𝜏 approach infinity. This also means that you cannot use the Pythagorean theorem to add velocities. In spacetime, you have to use the Minkowski metric, which is: ds² = c² d𝜏² = c² dt² - dx² it means the total velocity is c² = c² dt²/d𝜏² - dx² /d𝜏² = c² (Uᵗ)² - (Uˣ)² if you define the temporal velocity in spatial unit then c² = (Uᵗ)² - (Uˣ)²

[@localverse]

Thanks for the info! Gonna return to your comment a bit later when I have the chance to compare what you're saying to the visuals of equations in the video.

[@Pottyde]

Thank you very much. For some reason I struggle to understand simplified explanations, I needed this to get it.

[@sebas9174]

When I saw the title, I thought it was about us moving at the speed of light relative to an observer on the cosmological horizon.

[@felixowen2693]

Is that like the unruh effect?

[@Culando]

Everything comes back to circles and trig. There's no escaping it. Speaking of getting different sources of information, I have heard about this stuff about moving at the speed of light before, but it was great to finally hear your take on it as well.

[@Lycras]

Thats 'cause you live inside world managed by a self concious computer/entity. Kind of. can't better describe it. All energy and thus everything which comes from it, is alive. Yes even smallest particles are self aware and can think for themselfves. You just can not proove it yet. You can think of the world as like a holodeck from StarTrek, you just do not know the pass to open doors to the main world. 😁

[@ScienceAsylum]

Yep, the simple math is always there. People often ask me what equation I use the most expecting me to say "E=mc²" or something. The answer is always "the quadratic formula" 😆

[@angeldude101]

Sometimes they don't come back to circles. Sometimes they come down to hyperbolas! (Though it's still trig, just hyperbolic trig instead of spherical trig.)

[@goomyman23]

This is the video i was looking for! I dont think ive seen anyone else explain this. I believe you mentioned it was coming soon. Thanks for the many explanations, one of my favorite science channels.

[@GlenHunt]

I absolutely LOVE this relativity stuff, especially when we go TO THE TIMELINE!! Seriously, relativity does interest me the most...even if I am a geologist.

[@GraveUypo]

Hey... what do you think of this obsidian knife i'm holding on my left hand?

[@ScienceAsylum]

I love the relativity stuff too.

[@kuboteusz]

​@@ScienceAsylumMy dream is you making a video when you focus on the timeline; what exactly led to the discovery of relativity. Lorenz, Minkowski, who helped Einstein with maths on GR? To the timeline!

[@Penjulum]

@@GraveUypo Is that your LEFT HAND? or are you just looking at it from a different perspective?

[@proloycodes]

​@@GraveUypooh shit -- OP, run and don't get obsessed over obsidian!

[@localverse]

Always learn something worthwhile from your videos no matter how much advance knowledge I already had! This one had a slight vibe of your older videos in pacing which seems to blend nicely with your currently more visual content. Will re-watch one or two more times, as it went really deep. Love it!

[@nmccw3245]

Yep. Matt on Spacetime taught me that as matter I’m traveling through time at the speed of light.

[@1dgram]

always happy to see a good video on relativity posted

[@jayde4872]

Going into this blind I’m guessing some percent of our total speed is invested in movement through time. Edit: friggin called it.

[@ThePrufessa]

Yep. I learned this on another channel a couple of years ago. Came to see if he adds anything new to what I've already learned.

[@numbersix8919]

99.9% or so.

[@metarus208]

gj

[@simesaid]

Yup. Nice! Tho it might be more intuitive (or not) to just think of it in reverse, so... *"The faster you move through space, the slower you move through time".* 👻

[@ScienceAsylum]

Well done!

[@YoungGandalf2325]

So if we stop moving, we get to experience more time? Time to go lay down on the couch! 😁

[@anderstopansson]

The sloth knows better.

[@markoszouganelis5755]

Thank you Nick Lucid!🌈

[@BluDynamo]

Your channel is incredible. I truly wish I had a science teacher like you when I was in school. Perhaps I would have been inspired to focus on STEM.

[@Person-ef4xj]

Actually the faster an object moves through space the faster it also moves through time as spacetime is anti euclidean, meaning that the square of the spacetime distance is equal to the square of the distance through time minus the square of the distance through space. When an object moves faster through space it actually has to also move faster through time in order to maintain the same speed through spacetime, in contrast to what one would expect from normal euclidean geometry.

[@IronLotus15]

I think it depends on whose coordinates you use to measure the passage of time.

[@renthearchangel9479]

That was one hell of a smooth transition

[@YeloPartyHat]

A friend told me about this and I've been waiting eagerly for a great explanation from yours truly

[@vog51]

Who can't love this guy?

[@Electricmullets]

I see the edges of it, but I think I'm missing a few connections. Maybe the cake just needs to bake a little longer. These videos have opened my eyes. Thx!

[@juzoli]

Everything moves with the speed of light. We gain massful particles, by enclosing a massless particle, which is moving with the speed of light, into a confined space, like a quark or an electron. These particles act like a clock, where every so called “oscillation” of that massless particle is a “tick”. If we move the massful particle in space, the massless particle in it needs to move along, and less of its speed is spent on “ticking”. Therefore time slows down. And since all of the particles in our body is built like that, including our brain, everything slows down.

[@punkdigerati]

Man, Dwayne Johnson is really involved in relativity.

[@YuriLifeLove]

I always get excited every time you upload a new video...

[@ScienceAsylum]

I'm glad you enjoy them.

[@jeffreyjohnson7359]

Love the Eye of Sauron shout out...

[@Llakar]

I liked this explanation a lot. I learned a lot of this through the in-variance of the interval concept. That and c = 1. But this gives a good perspective where it clears up who's time is it anyway.

[@JimmyMcBimmy]

8:59 .... DAYYYYYUM. He's not wrong, though.

[@digguscience]

A new perspective on understanding the speed of light

[@cesarsosa4617]

I was confused by the thought I should be traveling at the speed of light from the perspective of a photon, but since photons don’t experience time or space, such perspective shouldn’t exist.

[@ssrphysics]

What happened to your channel? You are one of my favorite science education KZbinrs. You inspired me to start making pop-sci videos. But why is your channel now receiving fewer views, and I haven't seen your videos recommended by KZbin for almost half a year?

[@ScienceAsylum]

I have no idea. I've been struggling since September 2022. That's how this business goes. There are a lot of variables, most of which you can't control.

[@ssrphysics]

@@ScienceAsylum did youtube give you enough impressions?

[@ScienceAsylum]

@@ssrphysics Getting the algorithm to show the video to people is usually the first obstacle. It's hard to know how it judges what is good and what isn't.

[@linoxydable3676]

So we can say we are all moving "fast, fast"

[@alexvilonyay8597]

Another great video...I'll have to watch it again to really grasp it crazy for life!

[@adamrussell658]

Maybe a pov thing. Consider the twin paradox. Earl stays on earth, while his twin Rocky takes off in a rocket close to speed of light. They meet up in 10 years earth time. Earl has aged 10 years, but Rocky has only aged 5 years due to time dilation. So Rocky has traveled 10 years in only 5 years. He clearly was moving faster through time. He was also moving faster through space. They could not both have been moving at the same speed. Therefore they were not both moving at C.

[@jackfox5664]

I enjoy looking at this as an intuitive explanation of how falling objects get their speed from gravity. A falling object looks like it accelerates for no "good" reason-- nothing is pushing on it; where is the energy for movement coming from? When we think of gravity as representing the curvature of spacetime, and conceptualize all massive objects as moving through spacetime at c, it becomes apparent that a falling object isn't getting its acceleration from "nothing"-- it's just changing the direction of its 4-velocity, from entirely through time to mostly through time and a little bit through space.

[@Fluxikator]

Not even that. It's just moving in a straight line. It's just that space is warped. There are no forces in gravity. (A good analogy is 2 person some distance apart on the equator on earth walking straight north at constant velocity. The distance between them will get smaller until they meet at the North pole. But theres no force acting on them that results in moving closer. It's just that ther straight parallel paths cross each other)

[@jackfox5664]

@@Fluxikator Another good way of looking at it! What I mean in terms of your North Pole analogy is that the 2 people don't need a reason to start "walking" through bent space-- rather, they are always walking, just through the dimension of time, which through gravity has detoured slightly into that bent space.

[@Villaboy78]

Nice breakdown , seen the circle explanation on scienclic and you defo warm us up to that from a more beginner level . Awesome job on a really complex subject that is just there to shoot people down . I found it tricky to follow first time when I wasn’t watching the screen but your graphics really helped . Have a wonderful Xmas to you , the clones and your amazing wife 👨‍🔬👩‍🔬

[@ScienceAsylum]

I keep hearing a lot of people listen, but don't watch 🤔. Makes me wonder if, maybe, I should only put a graphic on the screen when it _really_ matters.

[@Villaboy78]

@@ScienceAsylum for instance it’s great to put you on while I’m driving , or cooking . Great to listen to and then review a second time in the evening when I can concentrate more . Defo no harm in the graphics though although it does mean less screen time for you 🙌

[@petehiggins33]

@@ScienceAsylum I always find the graphics to be essential but I have aphantasia.

[@sierra1513]

I've been trying to tell people this for years, usually they just stare at me blankly, but now I can show them this video instead!

[@hardik.m]

But spacetime is hyperbolic! (4 velocity)² = (temporal velocity)² - (spatial velocity)² = c² The magnitude of this 4 velocity is always c (using the (+,-,-,-) metric) So the faster you move through space, the faster you move through time.

[@Littleprinceleon]

Faster... slower...

[@plat2716]

I've always thought of it as you travel the speed of light through time and space. The slower you move through one the faster you move through the other.

[@alainbellemare2168]

Light is the canevas when the universe is expressing itself , the container is also the content

[@chuckoneill2023]

Best segway to the sponsor's message yet. I do not (yet) have an opinion on the content. I think three or four views will be needed before I "get" it. And reference to my copy of your book.

[@viralsheddingzombie5324]

I don't think time without motion is even possible. Time is a measure or description of motion. Also, in terms of our physical brains time is a sensory and conscious perception that can only exist as a result of molecular motion.

[@Insightfill]

8:20 "If a factoid sounds simple, it's probably at least a little wrong." Occam's lesser-known electric razor.

[@OrdenJust]

Hey, maybe the Science Asylum can market Occam's After-Shave. Which of course would be unscented.

[@lantonovbg]

You don't know how right you are. We are moving with the speed of light and light moves with a speed ... zero.

[@markoprskalo6127]

True

[@PrometheusZandski]

Love it when you show anti-intuitive concepts. Because all matter has to experience time, it can't ever put all it's velocity into space. Because light has to always travel at c, it can't ever experience time.

[@jonbold]

That 4-V is an important clue in how gravity works. Give light a reason to slow and Time has to change with it, which changes the accelerations in all the subatomics in every bit of normal matter.

[@imaginaryphi1618]

Good to see you in motion!

[@CT-pi2gl]

"Because of a weird quirk of reality," is gonna be my new favorite answer I give to questions about basically anything.

[@ScienceAsylum]

"Weird Quirk of Reality" would also make a good album name.

[@dibenp]

Loved this on Nebula ❤

[@brothermine2292]

Although it's common to use the Special Relativistic equation that's in hyperbolic form c²t² - x² = c²τ² which leads to the imaginary coefficient i when you take the square root of the negative term, as Nick did, I think that's a mistake in this context. It makes more sense to subtract the negative term from both sides of that equation to arrive at the Pythagorean form of the equation: c²t² = c²τ² + x² Next, divide both sides by t² to get c² = c²τ²/t² + x²/t² That's more relevant in the context of the "speed" through 4-dimensional spacetime, because τ/t is the traveler's rate of aging from the perspective of the stationary observer (the floating astronaut), and x/t is the traveler's speed through 3-dimensional space from the perspective of the stationary observer. Together those two terms provide the traveler's "speed" through 4-dimensionsal Minkowski spacetime, from the perspective of the stationary observer. The c² coefficient in the c²τ²/t² term is just the conversion factor between the arbitrary units of time & length, and is equal to 1 if the units are chosen appropriately: c² = τ²/t² + x²/t² Note that it's a Pythagorean equation, where the square of a right triangle's hypotenuse equals the sum of the squares of the triangle's other two sides. The hypotenuse is the "speed" of the traveler through 4-dimensional Minkowski spacetime (which has the time dimension orthogonal to each spatial dimension, which means the triangle is a right triangle). So the square root of the left side is the traveler's "speed" through Minkowski spacetime... it equals c, the same as the speed of light through 3-dimensional space (and it equals 1 in the appropriate units of time & length). This equation works for any kind of traveler, including light. And it does NOT have the imaginary coefficient i that Nick mentioned, assuming the travel through 3-d space isn't faster than light. The equation also tells us the rate of aging of a traveler that's moving through 3-d space faster than light. It's not negative... it's the square root of a negative number, so it's imaginary. But it's unclear whether aging at an imaginary rate has any physical meaning, so it might be impossible to travel faster than light (in Minkowski 3-d space).

[@Blakblooded]

I used this explanation once during a bar argument. I was too many beers in to go into the Lorentz transformation, length contraction, infinite energy, etc, etc. I feel vindicated! Although I don't actually remember whether I won or lost the argument, or why we even got into the discussion in the first place. 😅

[@vishalmishra3046]

8:17 - Actually it's true for both matter and light. How for light ? Due to length contraction the numerator (distance travelled) becomes zero. Due to time dilation the denominator (duration of travel) becomes zero. So, the speed of light becomes 0 / 0 = c (since 0 = c x 0). [ it could have been a different constant if meter was defined differently (without depending on c = 299,792,458 m/s) ]

[@sergheiadrian]

This video kind of blows my mind, because in trying to understand general relativity, I often imagined us traveling through time at the speed of light, and every time we gained some speed in the other 3 dimensions, is lowered out speed through time by the same amount.

[@valentinrafael9201]

Great video! Also, Ground News is amazing, thank you!

[@ScienceAsylum]

Oh good! I've always been nervous to take a news sponsor, but they seem like they have a good mission.

[@ThunderTurtle7]

I picked this up in The Elegant Universe but Nick always has a great way of teaching

[@wefinishthisnow3883]

The speed of light is really only limited by the speed of causality for which everything (seemingly?) happens instantly. But 'particles' that interact with mass (such as us) travel much slower than the speed of causality and therefore experience time. I tend to think of our current experienced reality as existing in slow motion relative to the actual 'speed of time' (speed of causality/light).

[@JonBrase]

I prefer just to think of velocity as the angle between two lines on a spacetime diagram (or rapidity as the hyperbolic angle).

[@ScienceAsylum]

Rapidity is the superior way to look at speed.

[@mariusfacktor3597]

6:51 "In relativity, the faster we see something moving, the slower we see its personal time pass" Here's what I don't understand. If you're the astronaut, then in your view, the rock's time is moving slowly. So one second for the rock is equal to several seconds for the astronaut. That means from the rock's perspective, the astronaut's time is moving really fast (many seconds pass for the astronaut while only 1 second passes for the rock). BUT that doesn't make sense, because from the rock's perspective, the astronaut is moving really fast and thus the astronaut's time should be moving slower.

[@ScienceAsylum]

*"If you're the astronaut, then in your view, the rock's time is moving slowly. So one second for the rock is equal to several seconds for the astronaut."* Correct. *"That means from the rock's perspective, the astronaut's time is moving really fast."* Incorrect. *"From the rock's perspective, the astronaut is moving really fast and thus the astronaut's time should be moving slower."* Yes, exactly this. They each see each other's time pass slower. The reason that works is because two observers traveling at constant velocity in a straight line never have more than one event in common. That means they can only ever agree on when to start their watches _OR_ stop their watches, but never both.

[@mariusfacktor3597]

@@ScienceAsylum Thank you. Intuitively it still feels like a contradiction. Can you entertain this thought experiment for me? Thought experiment: Let's replace the astronaut and rock with two pieces of cheese. Let's say that cheese starts with 0% mold and gets more moldy over time. Let's say the moving cheese goes out for 1 hour, changes direction 180 degrees suddenly, and then comes right back. At the point where it passes the fixed cheese, which piece of cheese is more moldy? From the perspective of the fixed cheese, the moving cheese will grow mold more slowly, so when they pass, the fixed cheese will have MORE mold than the moving cheese. BUT the moving cheese could say the same thing about the fixed cheese. So which cheese will have more mold? (Does the change in direction mess up the experiment somehow?)

[@thedeemon]

@@mariusfacktor3597 The cheese who went there and back will be less moldy when they meet. It's the famous twins paradox. I find these 2 short videos explaining it best: kzbin.info/www/bejne/eJicfomIhr6geLM

[@TetrahydrocannabissaurusRex]

Incredible video as always!

[@ScienceAsylum]

Thanks!

[@MOAON_AABE]

Videos about light are my FAVORITE 🎉 it can be so trippy and exciting!!!

[@user-xr6xi5ym6e]

For tachyons that travel faster than light, the arrow will point downward and time goes backward

[@suicideistheanswer369]

Yes! I have thought about it!

[@Jaggerbush]

Aren't we traveling faster than the speed of light? From a distant galaxys perspective - we are at the edge of their visible universe - and as such, we are moving away from them faster than the speed of light. The space surrounding us is expanding and we are being carried along with it, faster than light speed.

[@j_mase]

On another tangent… you mentioned your book. I need a copy, preferably signed! Thanks for continuing to make interesting content that expands our crazy minds!

[@Simonsays7258]

This is why we always measure light in a vacuum at the same speed. If we move faster through space in spacetime then we will move slower in the time dimension. More correctly, we're always traveling through time as fast as physically possible dependant on our velocity through spacetime.

[@lennierofthethirdfaneofchu7286]

Going off on a tangent about tangents.

[@ScienceAsylum]

Glad someone noticed 😉

[@radhikayagnik8526]

I love how the astronaut wasn't presumptuous "him"

[@__8120]

Seeing that circular spacetime diagram at the beginning gave me one of the biggest "holy shit" moments ever

[@BrianOxleyTexan]

This is such a good explanation. I wish my undergraduate classes had shared this, and 4-d thinking had been introduced earlier. The explanations of spacetime diagrams were more confusing that enlightening, and these were foundational to understanding later work.

[@ScienceAsylum]

The traditional method of teaching relativity is to start with algebra, but I've noticed that seem to ingrain misconceptions in people's heads. Starting with diagrams is the best method. There's a lot less room for preconceived notions to sneak in.

[@xyzabc4574]

And when you combine this fact with "now slices" that span the Universe and change what is happening "right now" in other parts of the Universe depending upon which speed you're moving...it's hard not to think of the Universe as one big pre-recorded event. Yes, I'm saying the future is pre-determined. It almost certainly has to be if someone on the other side of the Universe can see my future just by traveling at a different speed. We live in a pre-recorded simulation that is stuck playing on loop.

[@ScienceAsylum]

I go to the other extreme and think of the universe as one giant collection of _local_ "heres and nows."

[@OGPedXing]

"How can you move at the speed of light??" Me: 'Cause it's the only speed there is, baby.

[@Lucky10279]

The whole, "generalize things to death" joke is _awesome!_

[@ScienceAsylum]

😁

[@andrewrussack8647]

Fun fact: Rail Track Engineers refer to straight sections of track as ‘tangent track’!

[@ScienceAsylum]

Interesting!

[@b.munster2830]

It’s actually way more trivial. Speed (or frequency) is whatever you’re counting (milles, meters, ticks, seconds, etc) divided by a standard time unit, eg seconds. All matter travels through time at a speed of one second per second. If you measure your own speed through time, you’re actually measuring your own clock’s rate, which is always a trivial 1 (s/s). This is also the constant speed of the 4-velocity. Saying that the 4-velocity speed is ic, is technically the same, based on the idea that a time unit is an imaginary distance, like one second equals i lightseconds. It’s just a more complicated way of saying it. Personally, I prefer to think of it the other way around: time is real and spatial distance is imaginary time, so a lightsecond is an imaginary second and c = i.

[@ThePrufessa]

I remember learning about this before. Our total sum of movement adds up to the speed of c.

[@0-by-1_Publishing_LLC]

Not on the weekends, pal. ... That's when I move at the _speed of beer!_

[@ckq]

Someone asked me what speed do time travelers move at and I was thinking about this idea of change in time being inversely related to speed to some extent. Sorta made sense for me intuitively, but makes it concrete

[@autobotbladewing1134]

Now all we need is a case for or against the video topic with regards to space-time expansion.

[@AngryDuck79]

Thank you for addressing this. Too often I see people asserting that lightspeed is a barrier that can be crossed, and that time travel exists on the other side of that line, because they have this fundamental misunderstanding of the nature of C. They don't conceptualize space-time as a singular structure and still try to talk about space, time, and speed/velocity as though they're all separate things. And these aren't just simple members of the science laity. These are actual science communicators and otherwise well educated people who should know better. There is only one other science channel I've seen address this concept, and I share their vid every time I see someone make the flawed claim that C is some kind of barrier that can be crossed if you just have enough kinetic energy.

[@anthonyalfredyorke1621]

Science is Bonkers, thanks for all your great shows, Have a wonderful Christmas and New year. PEACE AND LOVE TO EVERYONE ❤❤.

[@ScienceAsylum]

You have a good holiday time with your family also 🙂

[@PieterPatrick]

Yep... I always try to explain this to my collegeas. But they look like they see a burning bush.

[@ragingfred]

If you attach a clock to a string and start spinning around in place so that the clocks tangential velocity approaches the speed of light how fast would you see the clock ticking. It's moving nearly the speed of light relative to you yet also appears stationary relative to you.

[@HyperFocusMarshmallow]

It wouldn’t appear stationary to you. It would be moving at close to the speed of light relative to you, at every instant right… So you’d see it tick with the appropriate amount of time dilation. My guess is that you’re imagining that we can transform away the rotation as well. We can’t. If you try to transform away the rotation, special relativity is not enough. Inertial frames always differ by a constant velocity, not by a constant rate of rotation. To transform rotation away you’d need general relativity. Rotational motion is accelerated motion. To get rid of the acceleration through a transformation you’d end up with a gravitation or in other words a curved space time. Curved spacetime can also have an effect on the clock rate.

[@stefansauvageonwhat-a-twis1369]

Oh my goodness, time speed and space speed are traded for each other, oh my goodness the relationship is quadratic-hyperbolic, thats why things at the 100% speed of light do not really experience time, theyre like, at the limit

[@ScienceAsylum]

*"That's why things at the 100% speed of light do not really experience time, they're like, at the limit."* Exactly!

[@EVG_Channel]

I know plenty of people who spend the majority of their 4-velocity temporally.

[@threeMetreJim]

All I know is that objects with mass make time run slower to the observer, even though their proper time is unaffected. Being a bit weighty, that explains why I always seem to be late, even though I could swear that my watch is keeping the correct time.

[@mickmickymick6927]

Man, Ground News are sponsoring every video in my timeline this month

[@ScienceAsylum]

They're really pushing their holiday sale.

[@shelley-anneharrisberg7409]

Great explanations as usual!

[@ScienceAsylum]

Thanks! Glad you appreciate them. I put a lot of thought into these.

[@jjay6764]

This is true and matter doesn't move through space. What we call time is just displacement in 4D spacetime. This is why everything shares the same spacetime interval. So the speed of light is like a projector speed. It gives you a limit to how fast displacement occurs in spacetime. So it's frame by frame by frame and the speed of light is how fast these frames can be projected. At the speed of light there's no frames or time. How can anything actually move through space when nothing can reduce the space time interval?

[@danberm1755]

That's a great way of thinking about spacetime. So much simpler than a ball bouncing as a train goes by 😉 Thanks for sharing 👍

[@DrDeuteron]

but the ball gave us dt/dtau

[@danberm1755]

@scienceasylum I don't know the numbers, but it seems like cosmic inflation could be explained by spacetime slowing down. Therefore everything gets farther from one another. Photons are identical to what they've always been, but spacetime itself is slowing down so interactions occur less frequently. Anyhoo, just a thought. Would love to see that video 😁 I've been talking about it for years with little traction.

[@danberm1755]

Note also that this would imply that everything is shrinking (I think anyways).

[@turtletom8383]

1:15 had me rolling

[@ScienceAsylum]

😂

[@matthorrocks6517]

It absolutely feels like I'm moving at light speed.

[@tom_something]

Since the magnitude of this four-velocity vector is always C (representing the speed of light in the three spacial dimensions and "normal" passage of time in the temporal dimension), we can take something's observed speed and derive the observed speed of its clock by treating those two values as two legs of a right triangle whose hypotenuse has a length of C. In other words, there is a tight mathematical relationship between the Lorentz factor and the Pythagorean theorem. And if you look at the Lorentz formula, you can see how an observed speed of C gives you division by zero, which is bad for it. Similarly, if one side of a right triangle has the same length as the hypotenuse, the other side has to have a length of zero and... you don't really have a triangle anymore. Not a very good one anyway.

[@X3MgamePlays]

This is very interesting. Right before this video, I read an alternative theory about the expansion of the universe. He explains that the universe has an expansion rate of the speed of light. But then only in the 4th dimension. Thus the space we see is 3d, but as a surface on a 4d sphere. Not does not explain the expansion rate we have found in the 3 space dimensions. But if we use that 73 km/s per Mpc, we can use it to calculate the age of the universe. Which then ends up roughly the same as what scientists have discovered so far. Maybe this "out of the box" theory, if correct, can be linked to what you explained in this video.

[@snuffybox]

You don't need coordinates to do algebraic manipulations on geometric quantities and in a lot of cases they actually hold you back, making things more difficult because you are constantly thinking about things in reference to the origin and the arbitrary coordinate frame . You can use geometric algebra to do a ton of amazing things absolutely coordinate free(including relativity but I am not very familiar with relativistic math).

[@ScienceAsylum]

You can do relativity without coordinates, but that wouldn't make much intuitive sense to my audience (which is why I don't talk about it).

[@albirtarsha5370]

Why does everything move at the speed of light? Why is the velocity 4-vector constant? Answering this seems fundamental to answering the question of what time is. All that other stuff about entropy feels like dodging the question. Even if everything were stationary, that doesn't prevent the formulation of spacetime and the constant magnitude of the velocity 4-vector.

[@volbla]

Ah. It's always confused me how we can talk about a velocity through time. Regular velocity is measured _in relation_ to time, so what would time itself be in relation to? It makes super sense that the metaphorical measuring stick is proper time! That's a trouble off my mind 😊

[@ScienceAsylum]

Glad I could clear that up for you 👍

[@adamrspears1981]

I am experiencing my reality at the speed of light.