What the HECK is Time?! (in Einstein’s Relativity)

In special and general relativity, we imagine time as just another dimension of space in something called "spacetime." Unfortunately, this picture leads to questions about determinism and free will. Is that really how it works? What does the concept of spacetime actually say about the universe and about time?
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[@lebeccthecomputer6158]

Dude I literally have a degree in physics and I still find myself going “ohhh” during your videos. I think we sometimes underestimate how incredible content creators on youtube can be at not just educating the masses, but clearing up misconceptions in those who are in the field

[@ScienceAsylum]

I learned so much more about physics while teaching in a classroom than I ever did as a student. As a student, it's easy to miss the nuances and connections (or forget them).

[@BulletMagnet83]

@@ScienceAsylum some of my best teaching moments (electronic engineering) have been when a student's asked me "why" about something I never even considered because I just black-boxed it and accepted that it works. My usual go-to in those situations is "you see what you can find out, I'll see what I can find out, and next week we'll tell everyone else about it". I've definitely learned more through being asked random things by students than actually going to college myself!

[@sicsemperevellomortemtyran3526]

If you really want to know if you understand something, try to explain it to someone else.

[@peterwor]

Me too, I worked in aerospace as well, really well articulated video.

[@wielentschoten575]

Causality? I don't think so.

[@gentlyschannel4193]

Einstein's girlfriend; I want two things from you, space and time! Einstein; what's the other thing?

[@frankschneider6156]

Alimony

[@srijansingh8124]

😂😂😂

[@glory6998]

😂😂😂👍

[@sMASHsound]

@@frankschneider6156 in the form of nobel prize winning.

[@n3izhyped622]

✌️😂😜

[@kiter2542]

"Time is a representation of causality" that's the best explanation of time I've heard. Thanks!

[@mikegale9757]

Exactly! The arrow of time and the maximum speed of time are properties of light. Entropy, schmentropy.

[@rkwatchauralnautsjediparty7303]

That actually blew my mind. I practically felt the synapses connect to help me get a little closer to truly getting the concept of spacetime.

[@wielentschoten575]

@@mikegale9757 no. Curviture of space determence the arrow of time.

[@mikegale9757]

@@wielentschoten575 if you plot a light ray on a spacetime diagram how do you know where to draw the arrow? one end of the vector is the light source. the other is the detector.

[@peace4045]

Casualty also means there is no way we can go back in time.

[@sufyanahmed1899]

This man is literally the best physics teacher ever, I don’t have words to appreciate you, you’re the best of all. The hard work you put in your videos will pay off !!

[@wealthychef]

s/will pay/has already paid/ FTFY

[@loturzelrestaurant]

@@wealthychef Know hbomberguy? The epic youtuber who once fed peanutbutter to a not-real dog??

[@erezsolomon3838]

*Feynman has left the chat*

[@do_notknow_much]

the same thing is said about the gazillion other youtube physics video makers. "The Best Ever" phrase needs to die and never be resurrected. Makes me sick to my stomach.

[@AbuMajeed3957]

WOW I am a physicist and I studied general relativity for years you basically summarized a lot of academic lecturers in less than 12 minute I am really impressed with your marvelous work thank you

[@ScienceAsylum]

Glad you liked it 😊

[@davidgumazon]

@@ScienceAsylum Interactions and Causality were big bros. Time and Space flex each other. So the Time is not Causality but actually just a Measure of Change, technically the cause and effect itself doesn't rely on Time but an Interactions of Matter in Space Causality. Hence you stated "Time is not universal anymore. It depends on an observer's motion and their proximity concentrations of matter and light." *Am I right?*

[@budove58]

He is definitely a great teacher.

[@phoenixamaranth]

Agree, same experience. Sat through several courses, but this was so much more clear and succinct. It makes so much more sense to see it this way.

[@ScienceAsylum]

@@davidgumazon Cause and effect is involved in all changes.

[@juniormynos9457]

"Causality is more important than time." Most profound statement I've heard in awhile🤔

[@Ebani]

Causality IS time, if nothing existed you wouldn't be able to talk about time

[@panperl1212]

@@Ebani If time had a beginning, which it certainly had, it has to be fundamentally less than causality itself. Time is an effect, since it had a beginning. Causality points to a cause for this effect. Denying this is denying the foundation of all of science.

[@gaeb-hd4lf]

@@panperl1212 Time is not an effect, is a measure of change, which is a consecuence of causality. In fact, the unit of time (a second) and mechanical watches are defined based on periods of things happening (a period esentially is the repetition of the value of a changing parameter)

[@Ebani]

@@panperl1212 Time doesn't exists, it's all causality.

[@Ebani]

@kwokshsee Causality is the natural consecuence of matter/energy, time is the human construct as causality goes hand in hand with existence. Time doesn't exists bc every moment in the universe is like a snapshot, when something changes (time passes) it means causality followed it's course and the universe as a whole changed but, like exposed in the video, every point in space/time is independent of each other, both time and space can change according to the observer but causality will not, ever.

[@matthewmailman1923]

This is an amazing example of first-rate teaching and organized introductory information for people without a background in physics, astrophysics, temporal mechanics, etc. As a teacher myself, I aspire to this level of information delivery. Bravo!

[@michaelbrown1627]

I’m a mechanical engineer and had to take quantum physics. I understood nada in the class. This dumbed it down for me so now after 25 years I understood.

[@nenmaster5218]

@@michaelbrown1627 If you are a mechanic engineer; a lord of the metal-screws; you will surely like more Science-KZbinr, yes? May i recommend some? It is my hobby, thats why.

[@dennis4248]

I‘m a teacher in Germany and I feel that I manage to achieve my teaching goals best by shouting at my pupils and creating an atmosphere of fear in class. It really works. P.S. if some pupils talk, I throw my keys at them. Check my ebook for more tricks.

[@wrjazziel]

Man, you are awesome, you always blow my mind, I'll stay today with: "Causality is more important than time"....

[@wrjazziel]

thanks for your like @mike lucid 😁✌️

[@rahuldamala7021]

Can we all take a moment to appreciate this guy's ability to summarise the entire existence of time under 12 minutes !

[@TheBrickagon]

Yes, and this is why I subbed faster than the speed of light :D

[@TheSCPStudio]

Well, our perception of the entire existence of time. I have a very strong feeling that time is nothing like what we think it is. We just are physically unable to comprehend it. However I’m just a random person so what do I know lol.

[@TheBrickagon]

@@TheSCPStudio you know more than I do, so... 🤷‍♂️😂

[@zephyrwinkle6552]

I watched in in half that time by speeding up the play speed. I also watched it on the second floor of my house so it would go a little faster....

[@ponscardinal2862]

A measurement of duration. Okay?

[@Rujenz7]

"does time exist" scientists: yesn't

[@-_Nuke_-]

That's more of a quantum mechanical answer :P

[@okboing]

h*ck my brain

[@Andrewy27]

I like nyeao better but ok. Its yea inside no and its the sound a Nascar makes... nnnnnyeaoooooooooo

[@frankschneider6156]

@@-_Nuke_- The QM answer would be: Yes and No, at the same time, but only if you don't look.

[@user-wv1in4pz2w]

does time exist? no, it does.

[@MegaAlphatron]

You are hands down the best teacher I've known in all the subjects you teach. I am a mechanical engineer, I used to ask my teachers, 25 years ago about this stuff and either they didn't know the stuff or didn't know how to explain it this clearly. I really appreciate your efforts and fantastic work. 👌🏼👏🏼👏🏼👏🏼

[@boyanfg]

Watching a video of yours for the first time, I thought that you are crazy. But the subject was well presented. After watching a couple of your science clips, I have to correct myself. You are an exceptionally good and knowledgeable lecturer, and you are actually quite funny. Please continue this good work!

[@faustin289]

*"Causality is more fundamental than time..."* This is very deep!

[@yoondami1127]

Yesss.. this line that Nick quoted solved my problem of explaining the subject to my peers. I always fall short of words when explaining time.

[@mrskynet8800]

And entanglement is more deeper than causality, since the change of states between two entangled objects happens instantaneously.

[@wielentschoten575]

Causality has got nothing to do with time. Time is not constant. It is relative. Space can be bend so can time. Entanglement is much more interesting.

[@nenmaster5218]

@@yoondami1127 Meanwhile, the arguably Best social commentary i know: Hbomberguy. Also funny af, tbh.

[@xapanxyi]

what is Causality?

[@LeOnIdAs162]

“Time is a representation of causality” FINALLY SOMEONE SAID IT IN A SIMPLE AND COMPREHENSIVE WAY

[@brotherman9757]

I was just thinking the EXACT same thing. Spacetime, smarter every day, sci-show, etc all missing the mark.

[@antigraphein943]

Yea, physicist's time. That's kinda known if you look up to philosophy. But look also Being and Time from Heidegger. Cause non-physicist human way to deal with time is also important.

[@solapowsj25]

The astronomical way of saying it is here: The causality of a Supernova in our universe spacetime is the size of a massive star and the presence of chiefly iron and nickel in its structure, so in time there's nuclear reaction with implosion and supernova formation.

[@mikegale9757]

Exactly! The arrow of time and the maximum speed of time are properties of light. Entropy, schmentropy.

[@mikegale9757]

@James Strawn I'm not sure if you were responding to my comment or the original from LeOnIdAs162. I'm not well read on Heisenberg or Dürr, but an open future certainly fits the bill here (in SR) because the objective reality of a spacetime event begins when light is emitted, absorbed or reflected.

[@tommylakindasorta3068]

It's like you're inside my mind. You know exactly the concepts that have been the most difficult for me to understand, and you explain them in a way I can understand. You have a true gift.

[@davegarofalo3663]

Been watching multiple videos about spacetime/gravity/etc and this has been the best one so far. It's starting to make some sense to me. thanks!

[@anujarora0]

4:15 Upon Michele Besso's death in 1955, Einstein wrote a letter of condolence to the Besso family-less than a month before his own death-which contained the following quote "Now he has departed from this strange world a little ahead of me. That signifies nothing. For those of us who believe in physics, the distinction between past, present and future is only a stubbornly persistent illusion."

[@tofu-munchingCoalition.ofChaos]

Dark

[@konradswart4069]

Yes. Even a genius like Einstein could have it completely wrong about time.

[@TheLastQil]

Einstein stated that, because if you apply special relativity to reality you get the Block Universe where past, present, and future all exist and exist simultaneously, meaning super determinism. Nick already did a video "Does the future exist?" postulating the incorrectness of this due to the nature of locality and light cones passing through an ever-present "now". Was good.

[@antonystringfellow5152]

@@TheLastQil I've just watched that video and I didn't leave it with the same understanding. Maybe I missed something. He certainly doesn't state the idea of only the present being real as a fact. Maybe the past and present do exist, in a fixed geometry. That would, of course, mean that free will is just an illusion, something find very difficult to believe but can't totally discount. Why we can only ever experience time moving in one direction would be easy to explain. That would be down to cause and effect. All that we experience is actually from the past and could never be from the future - our conscious self is constructed from what has happened (the past).

[@jensphiliphohmann1876]

@@@antonystringfellow5152 Even with past and future already existing, there is a way out of stark super determinism or ontological determinism: EVERETT's multiverse of possibilities. Of course, your conscious self is only one of many but it could also be one in the entire multiverse like a driver within a landscape who often has to decide which path he'll take.

[@ianmichael5768]

"Time is what prevents everything from happening at once." Wheeler Granted, everyone is trying to do away with spacetime these days. Excellent video!

[@thewhitefang007]

Ian Michael why ?

[@courrierdebois]

Everything is happening at once.

[@IVANHOECHAPUT]

Most people believe this was a quote from Einstein. Many believe it was by John Archibald Wheeler. The quote actually originated from a comic book and science fiction writer named Ray Cummings in a 1919 story titled "The Girl in the Golden Atom" for a magazine called "All-Story Weekly".

[@twstf8905]

Hahaha "Emeril's Original Essence" _(BAM!)_ 😂 It's like getting a really high quality, free educational refresher course, while being simultaneously entertained with ensuing hilarity. 👍 (Two of my favorites! 👏)

[@d.k.blackschleger8308]

I've been watching your videos for like 4 hours straight. Thank you so so much for explaining all of these things in regards to relativity, black holes, physics, etc. I also went ahead and bought your book on physics even though I'm no where near ready to read it - I know it will serve as a great goal for when I get there.

[@ScienceAsylum]

You're welcome. I'm glad you appreciate my work 🙂

[@anandverma7649]

The conclusion that time is a "measure" of causality blew up my mind, a lot of things make sense now. Even Gabe from PBS Space time had just speeded through the statement about the order of events, but you made it clear. Appreciate your hard work, keep uploading good stuff 🤗

[@admiraladama5877]

Anand Verma they even did a whole video on this. It’s awesome to have such great channels cover this subject. kzbin.info/www/bejne/o6S5pnZ7qJ2MmtE

[@anandverma7649]

@@admiraladama5877 Yup, I've seen this one, but this one focussed more on the invariance of the speed of light on an inertial frame, but this (Nick's) focuses more on why time is fundamentally a different dimension than space, even though they form a continuum. Yup, science channels like PBS and Science Asylum are a rare sight, but they're gold everytime they upload 😊

[@frankschneider6156]

The problem with this definition is that it breaks down, when you get to the quantum level, where the macroscopic cause-and-effect principle no longer exist, while time still does. Cause-and-effect implies hidden variables to be true. I'd like the univese to be like that, but it's pretty unlikely. Chances are that the universe is rather random on the lowest level and cause-and-effect is just an emerging property of higher levels. For this reason, it makes more sense to stick with the classical "time is a measure of increase of entropy in the universe, using Cs atoms" idea. This of course also breaks down, once you close in on the heat death of the universe (= universal thermal equilibrium) , but till then it might take a few more years or even a little longer.

[@anandverma7649]

@@frankschneider6156 Yes, I think that all of this boils down to: Does time cause motion, or does motion cause time?

[@MarcelinoDeseo]

@@frankschneider6156 well, we're discussing time as Einstein sees it. Besides, quantum mechanics and general relativity are irreconcilable as of this moment. It will be fun to see how these two reconcile in the future :-)

[@heavymeddle28]

"What time will you be home, honey?" "Mmmm... Around half a mile."

[@Damngoodcoffee_n_cherrypie]

That background music adds that just the right kind of wham to your videos. As a 90s kid, I’m totally feeling it.

[@khalidtheefirst]

A lot of physics channels out there keep using fancy animations and backgrounds without paying attention to the delivery, however yours are simple but they are so approachable and easy to understand, thank you for this amazing content

[@technicallittlemaster8793]

That was one of the best explanations I have ever heard.

[@kidzbop38isstraightfire92]

Really? Seemed fairly boilerplate to me.

[@kidzbop38isstraightfire92]

@Juanito G I'm not 100% sure I agree (or maybe I just don't follow). While I do agree that time represents change, I don't believe that a lower dimensional (n-1) object moving represents a gain in dimension. For instance, a 2d object (cartoon character) can move left/right and up/down and it still not count as a change in dimension. Without time, those cartoon characters would still be 2-dimensional (they have height and width when they aren't moving). Am I missing something here?

[@kidzbop38isstraightfire92]

@Juanito G oh yes totally bro, I agree with that 100%. Sorry, I just have misunderstood your previous post.

[@fidelio6311]

6:45 I've been watching 3blue1brown's lockdown maths and we just covered complex numbers. I love it when 2 unrelated videos compliment each other :)

[@jxmink]

This kind of thing happens often enough that I assume that there's a group of KZbin math & science channels, a cabal if you will, that secretly coordinates their programming, in an plot, one can only assume, to force onto us a better understanding of how the universe really works.

[@bierrollerful]

Yeah that is what made me appreciate maths only _after_ I had dropped out of university. All the interconnectedness was never really made apparent to me, or I just didn't pick up on it, although I desperately needed that to be motivated to even care about stuff like complex numbers.

[@MaziarYousefi]

Nice Combo.

[@davidgould9431]

I watched them, too! Weren't they great? I've only just stumbled on TSA and am enjoying it immensely, too. BTW, to compliment is to say nice things and I don't remember anything like that. Going together well is to complement. #EnglishIsStupid

[@ScienceAsylum]

@@jxmink I deny everything 😉

[@conanichigawa]

I just recently discovered your channel. This channel is great! When you said "nobody lives in a vacuum", I can see that it also applies you your channel. I can see influences from Wheezy Waiter, and you also said that you are a Nerdfighter. You also have a 3B1B plushie. Again, great channel!

[@leavethebasket7435]

I love your energy. These videos are gold!

[@thedeemon]

I got it: stinking squirrels accelerate, non-stinking squirrels move straight.

[@okboing]

Replace all of physics with this and BAM My own physics class

[@lyrimetacurl0]

If it farts in a vacuum then its path is curved

[@data007cz]

@@lyrimetacurl0 Actualy frozen squirels do not fart. The pressure of a warm fart would probably make it explode : - ) and it's path became 4D then.

[@adambell7122]

squirrel's can accelerate through spacetime with their natural nut fuelled 'Fartin Jet Propulsion Engine 3000'

[@new-knowledge8040]

No No No. You all have it wrong. Skunks accelerate, and squirrels move straight.

[@mufaddalkapasi1778]

"causality is more important than time" This line gave me goosebumps, never thought about it uptill now. THANK YOU

[@RF-fi2pt]

Agree. Why the things happen?: GRADIENTS is the other video of Science Asylum, where i confirm the deep sentences: our sense of Time is because exists Movement as our sense of Space because exists Objects, from an old teacher. Complement:Also 2 different observers always agree with spacetime interval (ds)^2,said PBS.

[@admiralhyperspace0015]

I did

[@johnd9031]

I got more of an understanding of space time from this video than any of the popular books on this subject I have read or other videos I have watched.

[@certs743]

Just started watching your videos and you do a great job of explaining some very complex ideas and concepts. If physics was taught like this when I was in high school I probably would have kept up with physics. Back then it felt almost like a test that if you were not smart enough to understand the convoluted explanations you were not smart enough to be in the class. You make all of this very accessible to just about anyone.

[@titusxp]

Clone: I thought you promised not to use a clone Nick: I changed my mind. I do what I want. That killed me

[@jeffwells1255]

You're one of my favorites, Doc, as you can get across some fairly sophisticated ideas with clarity and humor. The world needs more like you!

[@ScienceAsylum]

Thanks! I really need the encouragement right now.

[@robertbrandywine]

Is he actually a doc? I think he has a Masters. Not putting that down, though. Dyson Freedman did a good job of explaining why a PhD isn't all that.

[@adarshpathak4664]

I Appreciate All of his Efforts For Adding Humor And Making Explanations So much Interesting and Enjoyable...A much needed Initiative To Make New learning Experience

[@RogerTerrill]

wonderful description of time! thank you Nick!!!

[@darylewalker6862]

I’ve been wondering why the “s” stood for distance for decades, since high school.

[@ScienceAsylum]

Glad I could help 😊

[@saswatsarangi6669]

Exactly nobody told us and we just accepted it for some reason

[@jensboettiger5286]

If it helps "strecke" is a cognate for a stretch. As in, you can carry that for the next stretch.

[@nicoe.6199]

And just to clarify, in this case Strecke is better translated as "Line segment between two points". The meanings are slightly different between "normal" and "mathematical" german.

[@rmonico1]

Im not native english speaker, and understood nothing (of this part)

[@Pedritox0953]

9:05 "You better get used to the "d"..." xD

[@krzyszwojciech]

Also, it's a small 'd'.

[@returnofdjango10]

Lols

[@WillyKillya]

Notice how far apart he's holding his fingers when he says that, subliminal messaging

[@yerbool]

Great video. Awaiting the next video about causality.

[@philjamieson5572]

Excellent presentation. Thanks again.

[@evilotis01]

i don't know how you do it, Nick, but it's uncanny: every time I watch one of your videos, i have a genuine lightbulb moment where a thing about which i've watched umpteen other videos somehow makes sense in a whole new way. (this time: the idea of "curved spacetime" as... well, curved spacetime, as in curved spacetime diagrams. i'd never thought of it quite like that, and.... wow!) anyway, just really want to say thank you, and please keep doing what you do!

[@NG-VQ37VHR]

"Facts don't care about your feelings". Don't let Twitter hear you say anything even close to that.

[@oldoddjobs]

Is smug a feeling

[@wicked1172]

This is becoming my favorite channel.

[@Nm-kw3sj]

Absolutely the best explanation someone can find of general relativity . Thank you really a lot!!

[@rmonico1]

One of the best physics channel on KZbin. Not superficial nor boring.

[@parsa5290]

"how does he dare disprove our feelings with facts" I sense a reference there

[@anderstopansson]

Yäa, I like that.

[@VENOM-tx6gp]

What reference?

[@ADogNamedElmo]

@@VENOM-tx6gp ben shapiro

[@n9575]

I hope it wasn't in support of Shapiro tho...

[@n9575]

I hope it wasn't in support of Shapiro tho...

[@surivicky]

I always thought about it. But you made the revelation: Time is a representation of causality. Your knowledge answers my age old questions. All the best.

[@marcuspradas1037]

Excellent. So many thanks. In most of your videos I learn some thing/s, that I haven't seen in other videos or books or MOOCs. You're a great professional of scientific dissemination!

[@ScienceAsylum]

Thanks! 🤓 Happy to be helpful.

[@stephm4047]

9:16 : "you better get used to the d" 😳 😂😂😂 10:20 "if one event could influence another, then the order of those events is always maintained" 10:33: "Time is a representation of causality" 11:09 "Causality is where our concept of time comes from. Causality is more fundamental than time."

[@qinisodlamini1139]

After hearing about causality. I no longer have hope of time travel.

[@sniperpaul3432]

@@qinisodlamini1139 imagine what time travel would cause

[@joelosuna123]

@@qinisodlamini1139 After hearing about causality. I no longer have hope on free will

[@artz9643]

@@qinisodlamini1139 Regardless of causality, time travel into the future IS possible. Nothing according to our current understanding of physics would prevent it, in fact Einstein proved it through his Theorys of Relativity.

[@waking-tokindness5952]

​ @joel osuna Right! Those who say that "If our wills weren't free, then no one should be held to blame or to reward for anything" are surely trying to get somewhere; but, they’re apparently missing the fact that if our wills were all truly totally “free”, then such reactions as these two social ones would never have any causative effect upon any actor, whatsoever; thus, the fact such reactions do have some effect, at least usually, at least to some small extent, proves that our wills can’t possibly be totally “free” from being caused. More-over, given the confirmed ubiquity of Conservation~Causality, our wills, along w/ every other process, everywhere, w/out beginning or end, must thereby be being perfectly, totally, caused, w/ actually no “randomness” whatsoever in any reactions (which would violate this Conservation) anywhere, ever. --- despite that atomic-scale interactions seem to us to have random outputs; this is only because we are so huge, & the probes (e.g. photons) that we send at these tiny events, to try to observe them, only knock them about so violently that they _seem_ to us to be reacting “randomly”. Actually, tho, the fact that all macro-scale events, which always proceed within perfect Conservation, are composed of these atomic-scale events, proves that even these latter actually do so, as well.

[@whuzzzup]

You missed the opportunity in the beginning to say "who does he think he is, Einstein?".

[@ScienceAsylum]

😂😂

[@Lucky10279]

Yeah, that would have been hilarious.

[@ThePHOTOES]

🤣🤣

[@340wbymag]

A gazillion years ago when I was in junior high school, my science teacher taught us this about time; He said time is a measurement of change, just as a mile is a measurement of distance. It was the best explanation of time I have ever heard.

[@narfwhals7843]

Your teacher was very imprecise to the point of misleading. A second is a measurement like a mile. A second is not time.

[@Eliras24]

@@narfwhals7843 he wasn’t time is change. But what the General idea of time is, is that of the clock, meaning the Passing of seconds. Meaning the Measurement of time. So, with this poit of view, if you think about it, his professor was right

[@thedel775]

Everything is, perception, or as said, point of view. Narf, is simplistic because he works within our terminology of time measurement. Yes, there is no such thing as time...other than, it's a measurement, or more precisely, the making of causality within space-time. There is only the present, which is constant and infinite. I hope that perspective helps with your thinking....cause we would not be able to think without the constant renewal (space-time travels only one way) of the present...… there is no future or past, only the present. The present, constantly adds (causality) to itself in revolving perpetuity, thus, allowing energy and matter (us) in our dimensional space-time to think!

[@peterdamen2161]

So did my religion teacher. About 40 years ago he said that 'time is the measure of movement'. Already then I understood the significance of what he said. Thanks, mr. van den Brekel :-)

[@narfwhals7843]

@@peterdamen2161 You probably shouldn't let your religion teacher tell you what time means in physics.

[@galloe8933]

Wow, this channel is fantastic. I'm subbed!

[@crackedemerald4930]

"nobody lives in a vacuum" Or... Everyone lives in a vacuum, under an ocean of air.

[@jackalope2302]

You beat me to it.

[@ScienceAsylum]

🤔

[@subrosian1234]

And a magnetic field!

[@Lucky10279]

I don't get it.

[@nell6913]

This vacuum that no one lives in - is it a Bissell, a Hoover or a Dyson? Most likely an off-brand...

[@MaziarYousefi]

You actually have a very good ability to summarize and teach things easier. Nice video.

[@pacificovw9522]

Dude, I have to watch this over a couple more times to get it, when I have the time. Thank you for posting this.

[@jdkhaos4983]

Thank you for explaining curved spacetime so eloquently!

[@sjzara]

I just love your different perspective on things. I have known the physics for years, but then you add “causality determines what time is”.

[@doctordeej]

Superb video. You just get better and better. I asked myself “where were you when I was at high school?” Then I figured that neither KZbin or you were actually around back then.

[@josephmcgolrick3920]

I really appreciate your perspective. I've learned so much just from a few of your videos. I'll never look at Gravity the same again.

[@theprospector7719]

Love your channel! Thank you for the videos. I am beginning to understand the logic.

[@ScienceAsylum]

Glad to hear it! 🤓

[@elremito]

You have such an amazing ability of saying what many have said before you but just better and more accurately than anyone! I love how you don't forget the difference between model and reality... There's lots of philosophy hidden in the science you teach! Thanks :)

[@raydencreed1524]

@6:54, I think this is the first legitimate “mind blown” moment I’ve ever had. That negative sign just plops out so naturally from calling time an imaginary axis.

[@Gghjjjjjjjji]

Very well thought out. I enjoyed the explanation.

[@musicinsession]

Beautiful video!! Very well done and explained! Subbed!

[@itwasinthispositionerinoag7414]

You can measure spacetime with a clock that has rulers for hands

[@alexandertownsend3291]

Your comment made my day.

[@DaBlondDude]

Brilliant!

[@dougnulton]

@it was in this positionerino agadmatorino Big Brain moment 🧠

[@bierrollerful]

Damnit, I just posted another comment with that exact same thing!

[@user-xw3qb4li2c]

I just discovered this channel...and I'm VERY impressed. Clear and concise (and... quirky?) explanations that get to the very heart of the subject. Finally someone clearly distinguishes between model and reality. I know this is obvious to most physicists, but I have a feeling it may not be so to a layperson. To me it seems that people are drawn to theories such as the standard model or relativity (or especially string theory) because they purport to explain the fundamental structure of reality. It's just that the explanation, even if its predictions are accurate to within the error margin of the best experiments, is merely a model. No reason for nature to exactly follow our theories...or even to exactly be describable by math (some people make it seem as though God has a book with 'the equation' in it - and it is only up to us to find it). Sure this is all philosophical, but I think it is important to note as it shows what counts as "scientific fact" (at least when talking about physics on a fundamental level) is usually a complicated mixture of raw experimental data and the math (model/theory) with which one interprets that data (which is again used to modify the math and so on). Also, showing just some of the many people (mathematicians and physicists) who played a role in developing relativity earns you a huge plus in my book (...not that this should mean anything to you...figure of speech I guess). Usually people just start and end with Einstein when talking about relativity...which I frankly find somewhat annoying as they make it seem like the man single-handedly developed the whole thing from scratch, which feeds into this narrative of only godlike geniuses being able to give decent contributions to math or physics (and it doesn't seem to me that people think similarly for other fields of science, e.g. biology...though I could be wrong - I hear this guy Darwin is pretty popular). I tip my proverbial hat to you good sir, keep up the amazing work.

[@HIS_VF]

That’s very Interesting, you’re onto something there... cool video mate

[@paulduncan1483]

Your channel makes many complex concepts so much easier to grasp. Thank you

[@ScienceAsylum]

You're welcome. I'm glad I can help 🤓

[@spiderjuice9874]

Forget "What the HECK is Time?!" - what about: What the heck is SPACE?!

[@god3597]

No what the heck is heck?

[@spiderjuice9874]

@@god3597 The heck?!

[@rajatrathore4577]

I am agree with you...

[@horophim]

I give you one better... why is time?

[@anderstopansson]

@@horophim Is not time, is just the space between cause and effect at a certain speed...

[@toosas]

thats brilliant, 'causality is more fundamental than time'

[@tim_rizzo]

Just stumbled across your channel. Great stuff!

[@ScienceAsylum]

Thanks! 🤓

[@paco291]

Great channel - keep up the good work!

[@filipebcs8]

I have said this before, but your videos are amazing! It is so easy to learn a lot from them! Please, keep up the good work! Thank you!

[@ScienceAsylum]

Thanks! Glad you like them 😊

[@kevc5510]

His videos are amazing. Entertaining, educational, and funny all at the same time.

[@wuffb]

Love your videos! Fun and understandable!!

[@FrancoFluence]

Loved it! Thank you!

[@cordellblaine9641]

Love these videos (been on a binge about space/time/light for the last few weeks )- I've always used squirrels in my examples teaching my kids, so love seeing you also use squirrels - show's I'm not crazy because you use them too! Oh wait..

[@maciejfratczak4136]

he sometimes uses a cake as well :)

[@adityakelkar6860]

Saw Nick’s face in a thumbnail, clicked on it without looking at the title and liked it. Safe to say, it did not disappoint. Great video!

[@tinetannies4637]

This channel is awesome ALL THE TIME!

[@jehanr]

This is one of the best explanations of space time diagrams! Thank you for all the cloning

[@god3597]

This was the video I was waiting for, sir thanks for this.

[@nomi_4773]

I used to visualize in my head how curved space can cause gravity. I could not come up with an explanation and it just made me confused. watching your videos about time and gravity I now can visualize gravity. thank you.

[@ScienceAsylum]

You're welcome. Glad I could help 🤓

[@blankenstein1649]

firstly, thanks for making so many great videos. i'm not at all mathematically inclined, but i was always fascinated by science topics, especially physics and you do an amazing job at simplifying such complex ideas. second, as a californian, i can confirm that we measure distances by time as well. telling me that you're 5 miles away when i have to take the 405 to get there gives me almost zero information.

[@airchairairflare]

You explain everything really well.

[@r7diego]

- "Time is a representation of causality" - "Causality is more fundamental than time" Ok I'm going to have to chew this for a while, good time to be on quarantine, I don't fully agree on the concepts but very deep

[@tom_something]

I found an article from a few years ago describing the difference between time as we experience it, and that mystical forth dimension of spacetime. Like most of my favorite science discussions, it straddles empiricism and philosophy. It could make an interesting topic for a video. . I tend to think that the fourth dimension of a hypothetical "map of events" is somewhat different from a catalog of all events. I think a 4D plot is inertial by nature, and any non-gravity forces would cause this "chart" to actually bend over time, even to a multidimensional observer. And perhaps the energy required to bend a component of this chart takes effort, which could explain inertia itself. Or maybe the fourth dimension is similar to the imaginary axis (as in lowercase i). A sort of placeholder domain that exists and doesn't at the same time, which really comes into its own when applied in such a way that it interacts again with the real axis. An intermediate step within a calculation, that arguably doesn't exist on its own. And the consequence of its questionable existence is the exotic experience of time, a thing we only have one of, when we have three whole "space" things to measure in. . I don't quite "buy" the "we're living in a simulation" thing, but regardless, if we look at how physics simulations are generated on a computer, and the "bugs" that often arise from those simulations, a lot of parallels start coming up. So the analogy could be helpful in trying to understand some of the universe's more mysterious behaviors. But the simulation thing is a whole other discussion that I'd love to have. I have a few bar buddies that are super into theoretical physics, but with this stupid apocalypse thing we're going through right now, I lack the outlet. Something to look forward to when the skies clear again. . "Scientists suggest spacetime has no time dimension" phys.org/news/2011-04-scientists-spacetime-dimension.html

[@socialscientistshiva3321]

Great and informative video

[@vgrof2315]

Very good. Goofy as he is, he is very helpful in understanding these concepts. I appreciate it. Been thinking about these things a long time and think I'm closer to understanding them with his help. Thanks again.

[@jonhigdon5592]

Very cool. Took some mind gymnastics with the change in geometrical functionality, but learning with comedy somehow helps, thanks...

[@ShauriePvs]

As always it is such a wonderful explanation sir...I now understand why complex numbers are used here... P.S: Can you also explain ,ore about Non-Euclidean curves next time!!!

[@VISHALCHAUHAN-eg3tm]

your videos make me want to sit with you on a chilly autumn evening talking about physics and stuff while sipping red wine! if you would entertain such a thing!

[@oliverfunk]

Your videos are great, I wish you had more subscribers.

[@MASAo7]

Love your videos. I watch them whenever I have time. Or is that whenever I have space? Same thing I suppose! 😜

[@HavocEmblem]

Even though Im pretty sure this channel is aimed at a younger generation, I have to say that I am 36 years old and enjoy this channel very much even though I just discovered it yesterday. Also gotta say I love your taste in t-shirts XD

[@mspeachpeach5651]

@Adam Starry. Clearly it is relative. To me, you are the younger generation.

[@NicleT]

I’m 57 and still _eat_ his videos. Honestly one of the best scientific KZbinr when it comes to understand concepts. Short n’ sweet vids right on topic and funny. Perfect for any level of mind attention. It’s a precious channel.

[@hasanrahman6068]

Outstanding video.

[@kylemaharaj9563]

Amazing. Could you do a separate video explaining how those different spacetime diagrams are 90 degrees. I find it hard to wrap my head around that. Love your videos 🙏

[@tom_something]

The causal connection and the sequence of events is such an interesting concept. If A causes B, and B causes C, then we can all agree on the order of events. But if A causes B _and_ C, we will certainly agree that the first event was A, but there can be different opinions on whether B or C happened first. Fermilab had a thought experiment about a long train going through a short barn at a very high speed. If we're inside the barn (not recommended; send a clone), then the train will appear shorter than the barn due to its high speed. For a short duration, the entire train will be inside the bar, and we can prove this by closing the front and back door to the barn with the train still in it. But this doesn't work from the train's perspective. If we're on the train, we're still a nice long train, and the short barn has become even shorter. There's no way the train will fit. But at the end of the experiment, we will agree that both doors closed and opened while at least part of the train was in the barn, and nothing was broken. The difference is, from the train's perspective, the front and back doors did not move in unison. After the front of the train entered the barn's front door, the back door shut and then opened so we could get through. After the back of the train crossed the entrance to the barn, the front door shut behind it for a moment and then opened again. We'd wonder why they fiddled with the door like this, because from our perspective inside the train, we didn't fit ourselves entirely into the barn. To us, nothing particularly interesting happened that would warrant messing around with the doors at all. This would seem like a violation of events, because the farmer says the train was completely inside of a closed barn, and the passenger disagrees. But "entire train in barn with doors closed" is not _really_ an event. It's many events in a sort of system. "Inside of a barn with closed doors" is a complex idea that we've created in our minds because it's interesting to us. Less interesting to the universe itself. Every inch of that train, and every movement of the door, is a separate event. The only causes and effects here are the farmer's observations of the front of the train and back of the train, the farmer moving the lever, and the lever moving the doors. For both observers, those cause-and-effect relationships are preserved, as are the cause-and-then-effect sequences of events. At the end of the day, the universe doesn't take much interest in the things we find interesting. If we were the universe, and we had a plastic bag in space filled with some balls randomly bouncing around inside of it, we'd observe the the balls exchanging kinetic energy with each other and also colliding with the bag that contains them. And then some human comes along, and he's just looking at the size of the bag, and he says, "Hey look! The size of this bag is a function of the _pressure_ exerted by the balls, which is related to the _temperature_ of the balls!" And we, the universe, would be like, "What the hell is pressure? What the hell is temperature? Each ball has kinetic energy, and they're just bumping into each other and the bag. You don't need to add more names to things. Everything is explained perfectly just with these individual collisions. Calm down, you." And the person is like, "But there are a billion balls in the bag, and I want to think about what they're all going to do together." And the universe is all, "Well, there's no reason to do that." Because the universe doesn't share our hobbies.

[@maximkhan-magomedov431]

Nick has video about barn, too: something like "can you fit 6 feet pole in 5 feet barn", where he explains it. It's easier to understand how it works with Lorenz transformations. I think, 1minute physics explained in in transformations, too.

[@tom_something]

@@maximkhan-magomedov431 I like math in general, but I haven't really taken the time to "get" Lorentz transformations. The Lorentz factor itself is pretty intuitive, though. If you treat the speed of light as the universal speed of everything through spacetime (not just the speed _limit_ ), you can derive the Lorentz factor just from the Pythagorean theorem. I find stuff like that really cool.

[@waking-tokindness5952]

​ @Tom Haflinger et al.: Here loosely refuting that the speed of light is necessarily the maximum speed possible: Yes, the speed of light ["c"] is the universal speed of the propagation of most every perturbation thru, for us, our own most predominant all-pervasive field thruout this our own mega-sector of the universe; (-- most predominant for us, since we ourselves are composed of atomic components mostly if not completely made-up actually of - yes - light, which apparently is our field’s main type, if not its only one, of perturbations; i.e., perhaps all its perturbations being really just light, moving within or along it in various combinations of motions: spinning, orbiting, &/or expanding-out then collapsing somewhere into a “particle” [ perhaps somewhat like a soap bubble expanding then popping into just a droplet ] --) ; _however_ , is there anything prohibiting there being other vastly-pervasive fields besides our main light-field? -- perhaps extremely subtle ones; thru which, perturbations would of-course be more predominant to observers composed themselves of such subtle perturbations as well; in which other fields, probably, one or more main speeds of main propagations might well be quite different from “c”; slower, or, even perhaps sometimes, much (much) _faster_ ? After all, for example, there are at least _three_ main speeds of propagation within our common local ‘fields’ -- pools or seas -- of liquid water molecules: one speed being that of ripples just on any open surface of such a pool or sea (- ripples travelling at only a few km~miles per hour -); another being that of sound waves propagating thru it (which is a bit faster than that of sound thru air); & a third being that of light thru it (which is a bit _slower_ than that of light thru air, & BTW a bit even slower still than that of light thru a vacuum). In fact, the same probability, of even a multiple number of particular respective predominant speeds of propagation, must surely hold true, respectively, for actually every different medium or subsidiary medium ( -- “subsidiary”: e.g.: within our light-field, sub-fields such as water, air, misc. metals or crystals, glass, wood, or .. or even empty space). [-- Actually, of course, space is not “empty”, since every region of it all around us is apparently still a region of our own huge possibly-multi-bigbang-sized light-propagation field. (I.e.: Even in seemingly-”empty” space, at least in our sector of the universe, there is of-course at least one medium pervading thru it; one thru which light is perhaps its main type of perturbation; propagating along thru it at a near-constant rate “c”. ) --] So, even if some medium, invisible to us, happens to be (or be within) some field so subtle that we may possibly never detect it, nothing seems to require that any of its main speeds of propagation thru it or of perturbation within it must be less than the main one, “c”, of the field within which we ourselves are perturbations (since our atomic-sized parts, very complexly spinning, orbiting, interchanging, radiating out, etc, are all --- or at-least mostly all, so-far anyway --- apparently mainly just perturbations of this same light-field, in which “c” is apparently by-far the predominant, if not the only, speed of any sort of perturbation whatsoever). So, again, the notion that “c”, even averaging across its slight local differences . . (, depending upon in which subsidiary medium such as glass or water --- in-turn, itself within our same overall light-field ---that some perturbation is travelling,) . . the notion that “c”, +\-, is the maximum speed anywhere, thru any field whatsoever, seems now quite presumptuous.

[@tom_something]

@@waking-tokindness5952 Maybe, though it is certainly a bit eerie that the Lorentz factor, first conceived on a chalkboard, wound up being a pretty reliable predictor of experimental observations. If our current conception of the universe that that matter gets squished to an infinitely flat pancake that stops aging altogether as it approaches the speed of light, then it must be a pretty important speed limit.

[@waking-tokindness5952]

​ @Tom Haflinger One “yes, but” :: Again, "c" is indeed obviously the main speed of our own most-evident dimensions' predominant field, "the light-field"; meanwhile, however, relativistic effects such as "time -dilation" & "-contraction" are _always_ happening, in _every_ field, between _any_ perturbation-set ["soliton"] propagating along at one sub-max. speed & any other such set ["soliton"] going along at any different such speed. E.g.: Re solitons composed of sound-waves, travelling within, say, some easily-observable medium such as water, glass, or metal: ---- actually, all events w/in such media [ ‘sub-fields’ of our vastly-pervasive host light-field ] that we can detect or observe being also simultaneously mainly if not exclusively co-perturbations {-- along w/ us ourselves; altho, media must comprise quite constant perturbations per unit, in such contrast to us living fractal patterns --} . . , [all events w/in them being simultaneously co-perturbations] of our own locally- vastly- pervasive light-field (-- we basic-physics buffs tending to focus upon being apparently mainly solitons of it, even while surely also, BTW, simultaneously in other still-invisible dimensions, being solitons of other co-pervasive host fields as well --} ; still, in this particular example, referring to aspects of events not as-per their always simultaneously being perturbations of our host light-field but as-per their manifesting as sound waves within some such sub-medium [sub- of our host field(s)] --) : to any such sound-wave 'soliton', any another that were propagating relative to it would seem to be 'squished', along the sub-vector of each one’s relative translation[travelling], & proportionately to the difference in their speeds; just as w/ us as solitons of light in the host light-field, these relative contractions between the sound-solitons (contractions calculable via Lorentz’ & Fitzgerald’s ‘pythagorations’, BTW, just as w/ light) would become drastic especially as at least one of them were approaching the max. speed, in some direction different from the other’s [-- the max. (here, the “speed of sound”) for that type of perturbations in that particular sub-field ] ; & even more drastic as, while one were near-max, the other were approaching just zero speed relative to the components of that particular field [ the components in that sub-medium, which in either water, glass, or metal would be its molecules and their avg. repulsions to each other as-per their local density & temperature ] -- & then even more drastic still as that other’s direction of travel became ‘negative’, relatively [ i.e., as it came to include at least one sub-vector of motion in a direction opposite from any of the first one’s ] . So, yes: Relativistic effects, such as observed Lorentz contractions & dilations, are always happening everywhere, between any solitons mutually of any particular field; happening drastically as-per the difference in their speeds; which, agreed, must always be less than the max. in that field for their type of perturbation’s propagation thru the components of that field. --- less than the max. speed in _that_ field . . while perhaps far less, tho, than that in _others_ . ----------- {Disclaimer re me, FWIW: I myself am still actually only very vague about all of this re co-pervasive fields & local sub-fields, re relativistic effects, re time-space, & esp. re the mystery of universal Causality ~ Conservation ~ ’Inter-Accountability’; so, I am really appreciating being inspired, by such insightful videos & comments here, to think about & join in trying to further clarify all of this (esp. toward understanding Causality) ; in some ways already, all contributions here -- esp., for me, all sincere replies -- are carrying me up far more into Clarity than I’ve perhaps ever been. I hope the same can be said re as many others here as possible. }

[@karangandhi9795]

Amazing content

[@smlanka4u]

Thanks for the explanations.

[@midnightdragonfly9707]

I feel like practicing being in the ‘Now’, the present moment is a challenge for many. My takeaway at the end was that time causes or can cause a series of events and perhaps by being fully present and aware each moment, we can shift/ change those chain of events. Pretty cool stuff🤓🤯