Do we travel through time at the speed of light?
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- Опубликовано: 8 фев 2025
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In this video I explain why it is correct to say that we all travel through time at the speed of light and just what this means.
Support me on Patreon: / sabine
#physics #science #education
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Great explanation. I am a school teacher and I keep telling my students that we move through spacetime at the speed of light but they are not often convinced and it is nice to have an expert explanation to show them, thanks.
Yes, no doubt we move through spacetime at the speed of light. So that means if we are stationary we are moving through time at the speed of light. But it is unclear to me how do we know if we are stationary ?
@@Stan_144 I know it's difficult to wrap ones head around, but as soon as there are two physical objects and a movement can be observed, there is no such thing as absolute stationarity for anything anymore. Either everything is in relative movement to smth. else (depending on the position of the observer ) or nothing is moving at all.
@@Stan_144 No matter where you go, there you are.
I am an old timer, so I move in time with the speed of light as everyone but in an imaginary direction.
@@wkg19591 perfect explanation
There's an old adage that popular science authors will lose half their readers for every equation they include, and so libraries are full of books that deliberately exclude vital information despite the fact that their readers are making a concerted effort to glean precisely that information.
Thank you, Sabine, for flying in the face of that and daring to include and discuss these vital equations. Assuming that you're just as bold in your publications, you're doing a great service to anyone who's interested in self-education. Bravo!
I like living dangerously, haha ;)
@@SabineHossenfelder It's my 43rd birthday next month. I've just asked my mother if she'd like to buy me a copy of Lost in Math and she agreed to. 😎
It's actually mentioned in the first page of Hawking's A brief history of time.
@@nagualdesign It's an eye opener and you won't regret reading it.
@@nagualdesign I'm reading it now. One can't help but read it in her voice. It's very excellent. :-)
"And you would end up with the arguably correct but rather lame insight that we travel through time at one second per second". I love the dry deadpan humour.
You missed the forest by the trees, Lars...:)
When I assure someone of their accuracy in their provided information, I would definitely use absolutely correct. With out a doubt you are most correct. I certainly would not use an oxymoron to offer support as to say arguably correct. If it can be argued is it correct? No. To be correct is to have been agreed upon that it certainly is accurate information.
Every 60 seconds a minute passes in Africa
@@raudelulloa2597 are you sure?
It’s true that you move at c through time from within your own reference frame (like she alluded to), but from the frame of someone moving relative to you, you move through space as well, so your speed through time slows down, hence time dilation. Your overall speed through spacetime is always c from every reference frame.
I think that's the best way of putting it.
I guess it could just be pov but if you look at the twin paradox it looks like the reverse. Say there are twin brothers Bob and Roy. Bob stays on earth and Roy takes off in a rocket at close to lightspeed. They meet up in a year and Bob is older - because of time dilation. Bob the earth dweller experienced more time in that year than Roy the astronaut, so that means Bob was moving through that year of time for longer, which means Bob was moving through time at a slower rate. So Roy the astronaut moved faster through space AND faster through time.
@@adamrussell658 That is also false. It is no wonder when I got my H.S. diploma at 15, I gave up on the education system. There is no time dilation in space. You leave to Mars today. It takes you 1 year to go there and 1 year back. What year are you using as reference? The year of Mars is 5 or 9 Earth years. Unfortunately the Galaxy is moving and the Solar system is moving with the galaxy. That means without a doubt. The Galaxy and everything in it is moving at the same velocity. Forward. Which means it is today on the other side of the Galaxy. So if you went there and it took three years from us here. When you get back 6 years later you are only 6 years older.
Talking about time and not a single infantile michiokakuish-back-to-the-future reference
You are one excelent science communicator. Thank you Sabine
I read the title and thought, well...........
Do we!!!????
Now im subscribed! Great video, going back into the library... Thank you :D
During lockdown I have read "Lost In Math" I'm taking it into work next week (secondary schools open again) because I want some of my colleagues to read it, they are stuck in their ways and won't budge, Lee Smolin and yourself Sabine speak volumes about science being stuck in a trance seeing no way out.
Hopefully they will read it and have a clearer mind.
Thanks for writing such an excellent book.
Happy to hear you found it useful!
I have also read 'Lost in Math' during lockdown and it is an excellent read. I did enjoy the debate on PBS spacetime that involved Lee Smolin and Sabine about theories of everything. I will also be suggesting it as a read to colleagues at school and also to a-level and possibly other students.
Old joke: If the only tool you own is a hammer, new problems tend to look like nails.
- Anyone who has worked in a notation such as a mark-up language, programming language, or with specific design tools knows that the tool tends to constrain your imagination - if you don't watch out.
- Physics students are immediately taught vector algebra ... it seems harmless enough.
@@richardgreen7225 I think the bigger problem may the specific type of math they are using. Obviously if we want to make quantitative predictions we need some system which can produce numbers from data, which would likely be called a type of "math."
Which book is better, Lost in Math or Not Even Wrong? Or, alternatively, what kind of reader is each book suited to?
This was one of the best videos you've made. Thanks for always being so math minded as well as presenting simply.
I was just working on this this week. It's a stream of serendipity watching your videos.
Thanks a lot Sabine for sharing your insights in GR and QM. Becoming an expert and still keeping an understanding of the perspective of non-experts is precious. Bravo and thanks again for you enlightenment.
"All these fifty years of conscious brooding have brought me no nearer to the answer to the question, 'What are light quanta?' Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken. … I consider it quite possible that physics cannot be based on the field concept, i.e., on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics." (Albert Einstein, 1954)
"But maybe that is our mistake: maybe there are no particle positions and velocities, but only waves. It is just that we try to fit the waves to our preconceived ideas of positions and velocities.The resulting mismatch is the cause of the apparent unpredictability."
(Stephen Hawking, "A Brief History of Time" 1988)
"Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon..
Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion
"History abundantly shows that people's views of the universe are bound up with their views of themselves and of their society. The debate in cosmology has implications far beyond the realm of science, for it is a question of how truth is known. How these questions are answered will shape not only the history of science, but the history of humanity." (Eric Lerner, 1992)
“..it is utterly impossible for me to entrust anything to future ages without its first being passed through the hands of those that have an interest in suppressing it.” - Rousseau
I understand no comments. I must say I admire your guts/"balls"/ courage in stating what you believe regarding "big collider" right or wrong.
A physics video that I actually understood the equations presented. A miracle. The videos by PBS Spacetime are cool but always fly way over my head. I'm a data scientist, so my knowledge of physics is whatever I learned in a first year undergrad course and RUclips videos. Impeccable explanation in this video.
I watched it 10 times and I still don't get it
Best transition to a sponsorship ever! That was...well...brilliant! Haha
I don't understand the math (dyslexia sucks) but I'm comforted by the fact that there are people out there like Sabine who do.
You just fancy her! Admit it Sir!!
@@UnearthlyKiss Are you kidding? I've been crushing on her since I first saw her! Which clearly was more than three years ago.
@@tarmaque Well don't worry about it, she's turned me into a lesbian!
Or rather, dyscalculia?
@@ZeonGenesis Probably, but my actual diagnosis is "dysgraphia." That is, the tendency to draw letters backwards. I mostly overcame that, but I still have a lot of trouble with math because I can't remember formula and have a hard time with operations. I can do basic math up to algebra, but I fall apart in geometry. I _understand_ basic geometry, but I have a hard time connecting the formula to the problem. Beyond that it's all Klingon to me.
All of which are sub categories of dyslexia.
I finally have begun to intuitively grasp "spacetime". I am humbled. Existence is indeed sublime.
Thank you. A taste of this is enough to compel me to take the math classes I have been avoiding my whole life (I am 40) at tbe community college. I am simply astounded.
The first time I heard this explanation was in Brian Greene's book 'The Elegant Universe' and I had never heard it before. I searched around on the internet and all I could find were forum posts about having read it in the same book, asking if it made sense (the forum posters seemed to agree that it was a novel but not incorrect interpretation). That was probably around 2012 or so, and since then it has become a more commonly mentioned physics trivia. Interesting to see it explained properly here.
My 'annus mirabilis' was 1999 when I read every science book in my local library (to be fair, it was only a single shelf but still 3~4ft of books) and I remember learning this from one of those. It may well have been _The Elegant Universe,_ which I definitely remember having read. I had to Google to confirm that it was published in 1999 and not 2012!
@@nagualdesign ah yeah, I just meant that I read it around 2012, not that it was published then.
@@kebsis Yes, I realize that now. The bit that confused me was *"since then* it has become a more commonly mentioned physics trivia".
There was something on vSauce 'which way is down' video, but was more general relativity, whilst this is more special relativity and this includes actual equations and all that, whereas vSauce was likely doing origami or something to explain it.
Greener explained that for a body at rest, all motion is through time. As speed increases some of the motion through time is diverted to motion through space. At the speed of light all motion through time has been diverted to motion through space. It also explains why nothing can go faster than c.
Thank you so much for giving a formal answer and then giving an equivalent but more insightful answer as well, it really helps
She is hitting it out of the park !!.. many thanks!
Oh. My. God. Literally everything you said made sense to me. I don’t think I really even understood 4 dimensions up until now. So much at once yet I don’t feel overwhelmed. Thanks a million!
I absolutely love the way you explain physics in your videos. Physics is awesome.
After seeing this video I ordered Sabine's book and subscribed. I am a spacetime enthusiast who avoided math in school, bit realized I need math if I want to satisfy my curiosity. After a few years of off and on self study, I am at the point where I can (sometimes) understand physics concepts better when the explanation of the concept or phenomenon is provided through the math and formulas. It is so much more interesting that way. Guess I'm a nerd. But anyway, this is the kind of content I really dig. Also, I like Sabine's online personality. Really cool.
What a great video! I love how you manage to explain x+c*t and the -1 for space vs 1 for time in the Minkowski metric by bringing in speed invariance. I have studied relativity way back when, and thought your video was a nice way to explain it to my non-physicist students.
Wonderful - You have been divinely blessed with the ability to explain stuff really clearly so that a dunce like me stands a good chance of understanding it.
Many thanks.......all the way from London !
Loving this channel after discoveirng only a few weeks ago. Really clear explanations and each just the right length to absorb.
EXCELLENT presentation. You should be very proud of this work.
thought I was seeing a Feynmann diagram on her dress
Now that you say it!
Danny Morgan I was thinking handcuffs.
@@SabineHossenfelder Physicists too can have dirty minds and see things that are not there!
@@jceepf ???
@@DavidPumpernickel I mean seeing Feynman diagrams where they are none. During the movie Psycho, the shower scene was cut so well, that the censors saw naked breast while in reality the actress was entire covered!!!
Just a bad joke!
Ma'am Thanks.God bless you.you give us such precious information 😇😇😇😇😇.
Your style of teaching is great.
If my teachers teach like you then in 30 years shall visit Proxima centauri
Thanks 😇😇😇😇😇😇🙏🙏🙏
I'd think of this from another angle. Space and time are measures we as human defined by observing our environment. The relation between time and space, and therefore c is defined by us based on that. A more suitable approach would be to say that there is a constant "push" which gives particles motion through time and space. Meaning we are always moving with that push (c). We have a fraction which is describing our rush through space and another portion tells us how fast we move through time. It would be interesting to find out what time dilatation factor we have on earth spinning around while flying through space(time), all in relation to the CMBR.
Its probably not much since we see no apparent frequency shift in any direction of the CMBR.
I'm late to the party, but I was looking for a discussion like this. Some calculate that we on the surface of the Earth, plus with the motion around the Sun and the Milky Way center (at max swing), are in motion around some 480,000 mph! Add another 17,500 mph for those in the ISS (when in the correct direction, naturally), but doesn't their and our clock move that much slower? Is it even a whole percent? And relative to what? Is there any perfectly still point in the Universe? Probably not if it's a Torus shape. But haven't scientists ruled that out already? Don't satellite clocks move slower just being further from the Earth's gravity well? I have so many questions about these ideas.
Brilliant. What a lovely compact, clear, and yet intuitively appealing treatment of this fundamental material.
Another fabulous video. Very well explained. Thanks for sharing your knowledge with us.
The theory leads you to this idea of permanently being traveling in spacetime at the speed of light, but I never knew how to demonstrate It. Thank you, your prove was crystal clear!
My daughter is taking her first year of physics this coming week and I’m so excited for her
Great! My first degree is in Maths with Physics. I loved the course, and I found it useful for the rest of my life (although I worked in computer science, not natural sciences).
The best explanatory book on this was was written by a non-physicist, philosopher Bertrand Russell and is very accessible to the general reader. It's entitled, "The ABC of Relativity" published in the 1920's.
Direct, clear, concise and all in < 7 minutes!
Yes yes, I totally understand and love this topic (my brain weeps desperately trying to grasp these lessons😭) love the content!!
I think in an intuitive sense it can be explained fairly simply as well, though of course relying on some assumptions:
Speed, distance/time, has a maximum value we call "c" -- the speed limit of the universe. Objects in space move through time at a constant rate (yes their time can dilate, but the speed limit is the same for all observers), they are "pushed" through time (or falling through time if you prefer). Since a massless particle experiences no acceleration, it cannot actually move at any speed other than what that speed limit allows. It will always move at that speed, and that speed is fundamentally related to time. Nothing can slow it down, so it travels only at the speed of time.
Feel free to give your thoughts/criticisms to my intuitive "model". (Cannot think of a better word than model despite "model" feeling wrong)
No, massless objects travel at the speed of causality through space only. Massive objects travel through both space and time. The total speed is still c, but it is split between time and space
@@AverageAlien
That's a cool perspective to think about for sure.
That said, massless objects must move through time. Movement through time is required for change in state, including position. This is why we can describe their movement with a speed, which depends on time.
@@kiraPh1234k From our perspective, they do move through time. From their perspective, they don't. Light doesn't experience any time. For a photon, the universe is contracted so much that it basically exists at the beginning and end of its journey simultaneously.
@@AverageAlien I heavily disagree. There is a fundamental issue with these edges cases in SR and GR, it's where the models break down.
Obviously, these are currently the most accurate models we have to describe spacetime. The predictions of singularities, or perspectives of photons existing instantaneously from their perspective are not yet verified and we have every reason to think they are wrong. They would be the only example we've ever seen where a prediction of singularities wasn't from a problem with the model/math. In all cases this far, it has itself predicted the model to be incorrect/incomplete.
A consequence of the instantaneousness idea as well is that other photons traveling around the one whose frame is experienced "see" that they all reached their destination before themselves as they also see massless objects moving at c in relation to their frame.
@@kiraPh1234k ah. I hadn't ever thought about that. From their perspective everything else would also seemingly exist everywhere at once if that was the case. So does the universe contract at all from the perspective of the photon?
I find it easier to think of it like this;
Take a right angle triangle, where the hypotenuse represents an invariant spacetime interval, one side is time and the other side represents the 3 dimensions of space.
The length of the space interval would be the square root of the spacetime interval squared MINUS the time interval squared.
Likewise, the length of the time interval would be the square root of the spacetime interval squared MINUS the space interval squared.
You can immediatelly see from this that if you are not moving in space, the time interval is the same magnitude as the spacetime interval, and that as your velocity in space increases the time interval decreases, to the point where the space interval is the same magnitude as the spacetime interval, and the time interval is zero.
should be plus, it's hyperbolic
I have goosebumps everytime Sabine says einchstein
I get something, but it ain't goosebumps.
That's actually the right way to pronounce it because it's a german name
@@Camexplode I would say its not the pronunciation and more how crazy cool he was. Its like you hear he is smart in school, but you really don't know why too well until you hear people talk about him and what he has done/said specifically.
You have a way of explaining things. It warms up my heart and get my brain thinking! Thank you.
This is so helpful. Might have to listen to this one several times...
great explanation and a brilliant transition into promoting your sponsor
Sabine: Yes, that guy again.
* Einstein winks
Simple no nonsense explanation. Thank you !
I know this is unrelated, but I love the way you pronounce Einstein. Us native English speakers can't say it nearly so well.
So, we are moving through spacetime at c. So, we divide up c into a space part and a time part. So, when we are at rest we travel through time at rate c. If we move at rate v
Thank you for making complex stuff simple. I really appreciate it.
"All these fifty years of conscious brooding have brought me no nearer to the answer to the question, 'What are light quanta?' Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken. … I consider it quite possible that physics cannot be based on the field concept, i.e., on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics." (Albert Einstein, 1954)
"But maybe that is our mistake: maybe there are no particle positions and velocities, but only waves. It is just that we try to fit the waves to our preconceived ideas of positions and velocities.The resulting mismatch is the cause of the apparent unpredictability."
(Stephen Hawking, "A Brief History of Time" 1988)
"Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon..
Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion
"History abundantly shows that people's views of the universe are bound up with their views of themselves and of their society. The debate in cosmology has implications far beyond the realm of science, for it is a question of how truth is known. How these questions are answered will shape not only the history of science, but the history of humanity." (Eric Lerner, 1992)
“..it is utterly impossible for me to entrust anything to future ages without its first being passed through the hands of those that have an interest in suppressing it.” - Rousseau
I had never thought about this. This is a very interesting topic to have uncovered. Thanks!
If you don't believe this, wait till you are older. You'll find out just how fast you are traveling thru life, i.e. time.
Aging is accumulated damage so we could intervene to dramatically increase our lifespan.
I'm currently at a speed of 2 weeks per day
life != time
Every year is getting shorter, never seem to find the time
Plans that either come to naught or half a page of scribbled lines
@@lxathu Amazing album. ruclips.net/video/944y9HlLmqw/видео.html
I like the teaching style of this great mam and how she teach hard part of Physics in simple way using equation.
Fascinating. Sabine, that was a beautifully explained, easy to follow answer. I love your channel. ✌️🐝
the question is specious! (capziosa in italian language)
for v = c
mass is infinite and energy infinite : impossible
for v > c the formula of Fitzgerald Lorentz given a complex number
v = c v> c the travel in the space time is impossible
good travel....
God I love this channel.
First watch, god she's brilliant
Wow, that was s cool even though I've not yet grasped it.
The more I watch Zabina the more I just want to dwell within her aura. Thank you my dear.
Aahh... finally something everybody wants to know!!
Brian Greene explains this succinctly in his book The Elegant Universe. At all times, sum total of our velocity in space-time is equal to that of light. It may be zero in space, but is 186,300 miles per second in time. But as we move in space at higher and higher velocity, the velocity in time slows down according to the Special Theory of Relativity. Sum total of velocity in space-time will be same, I.e., 186,300 miles per second:
Wait, I think that means dS = 0, meaning we aren't moving at all. Now *that* makes sense.
"Do we travel through time at the speed of light?"
I would say so. I'm nearly 50 and it feels like I was an infant just a few years ago.
You mean just a few light years in the time direction ago.
@@XKS99 Something like that. My brain hurts :D
I'm 36, and it feels like I'm still an infant.
Wait till you're beyond 50 and you get told by your spouse that you act like a child and you figure, you still are.
Sometimes you leave me behind at the speed of light... :-) I really enjoy and appreciate this channel. Thanks for sharing.
At my age, I just can't move through time as fast as I used to.
I have the same problem, but I figured it was due my gravitational field being stronger due to me being more massive these days.
Lol. Me neither
Eh? What's that, you say?
you mean can't move through space as fast...time consequentially speeds up
With this topic, I think it helps to imagine reality as a video, much like any RUclips video, and you can move the slider as fast as you want, thereby controlling the rate at which time moves.
Was that Pixar founder Ed?
Either way: Hey Ed! We love you!!!
Concise, clear and crisp explanation. And to quote the winking old man "Make everything as simple as possible, but not simpler"
Please tell us about what physics says about the possibility of the universe being anisotropic. What might be the implications?
Well, the universe arguably *is* anisotropic, just look around you! It's all a matter of scale...
exhibiting properties with different values when measured in different directions
Are you referring to the papers by Webb et al ?
This is a great explanation for a seemingly very counterintuitive idea. Thank you.
I love how you think and how clearly and concisely you explan things!
luv u sabine you always explain science in ways i can understand
excellent, you said Euclid's formula shouldn't it be pythagorus's formula
Yes, that would have been more accurate. Sorry about that :/
I wanted to mention the same thing as a correction, but I checked and it seems ok to refer in three dimensions as the Euclidean formula. Of course in two dimensions is indistinguishable from the Pythagorean formula.
Great scientist, great channel !
Hey congratulations, you got featured in Space-time.
Absolutely the best Physics channel on RUclips. Dr. Hossenfelder cuts through all the nonsense and gets right to the point, with enough detail to enlighten the non-PhD viewer. She is a Physics rockstar in my opinion.
I can heartily recommend "No-Nonsense Quantum Field Theory" by Jakob Schwichtenberg. It's describing exactly this in a very clear way in the beginning of the book. No single step is omitted just as Sabine does. In my own words, our movement through spacetime is constant. The more we travel through space, the less we travel through time. A massless object only traveling through space experiences no time. Truly marvelous.
I can make sense of that! Well put.
You're absolutely right, though there's actually a subtle but important distinction between what you and Sabine are describing. Sabine is talking about the _coordinate_ velocity, which is not constant and depends on reference frame since each observer has their own time. What you're talking about is _four-velocity_ , which is arguably the more natural notion of velocity through spacetime. The magnitude of the four-velocity is indeed constant no matter your reference frame (and is equal to c) for the reasons you said.
There is a distinction between “coordinate time” and “proper time”.
@@spinor Absolutely. If I'm correct she describes the situation in which there's no spatial displacement, for which the notions actually coincide, isn't it?
@@AnnevanRossum yep! Exactly.
At this point including the math is making it easier to understand while the conceptual information alone is more clear then ever.
Good old Albert, he is rather like beer, the cause of and solution to all of life's problems; relatively speaking of course.
@daMyTPnessRex wrong "sabine" channel, Bob
I expected... "beer... you always want more " 😀
@@upublic plz tell wich is te correct one. tx
Your book, Lost in math, sits in my collection next to: A brief history of time, Rupert Sheldrakes: Science set free, and Bill Brysons: A short history of nearly everything. And Michael Endes Momo. (This might give you a good idea of my world view ;)
I’d love to see you interview Sheldrake.
0:54 *Every 60 seconds in Africa, a minute passes*
I have no idea what you said but really enjoyed it. Seriously.
Wow, cool! I love these totally nerdy and theoretical explanations of physical identities!
At 5:15 you show that if delta s = 0 delta x over delta t equals +- c. Isn't that a proof that c actually is the speed of light? Because the only speed that is equal for every observer is the speed of light, right?
Best regards
First time I’ve come across this claim and thanks to your explanation i understand where it comes from.
What I do not understand is why we set only the delta space variables per unit time to zero to denote a state of rest in space-time.
Sabine: "We travel through spacetime by the speed of light"
Me: "You definitely never saw me at work"
_"But time is different, because we can not move through it freely as with the spatial directions."_
*Is this true though?* 🤔 I.e.: can we really move through space freely? Consider the following:
1) You *always* move through space, relative to someone. There's no "halting" in space.
2) Who's to say when you move "forward" through space, and when "backward"? It's always *_net positive._*
Looking at it this way, movement in time doesn't appear to differ much from movement in space, does it?
Almost like a highly advanced Polaroid film on a continual feed leading to a end result.
Nicely explained, easy to understand and interesting, I enjoy these videos, they tend to help me grasp more clearly the complex things I try to learn from books. Without youtube and vids like this I would still be very confused.
"All these fifty years of conscious brooding have brought me no nearer to the answer to the question, 'What are light quanta?' Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken. … I consider it quite possible that physics cannot be based on the field concept, i.e., on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics." (Albert Einstein, 1954)
"But maybe that is our mistake: maybe there are no particle positions and velocities, but only waves. It is just that we try to fit the waves to our preconceived ideas of positions and velocities.The resulting mismatch is the cause of the apparent unpredictability."
(Stephen Hawking, "A Brief History of Time" 1988)
"Commendation from NASA for research work at Massachusetts Institute of Technology on the Earth's atmosphere and the Moon's surface for navigation of the Apollo spacecraft to the Moon..
Dr. Milo Wolff has found the structure of the electron consisting of two spherical quantum waves, one moving radially outward and another moving radially inward. The center of the waves is the nominal location of the electron 'particle'. These waves extend infinitely, like charge force. All 'particle' waves mix and contribute to each other, thus all matter of the universe is interrelated by this intimate connection between the fundamental 'particles' and the universe. The natural laws are a direct consequence of this Wave Structure of Matter (WSM), thus WSM underlies all of science." spaceandmotion
"History abundantly shows that people's views of the universe are bound up with their views of themselves and of their society. The debate in cosmology has implications far beyond the realm of science, for it is a question of how truth is known. How these questions are answered will shape not only the history of science, but the history of humanity." (Eric Lerner, 1992)
“..it is utterly impossible for me to entrust anything to future ages without its first being passed through the hands of those that have an interest in suppressing it.” - Rousseau
1st
well, not really.
but time is relative, you know?
I love the way you say Einstein. I would watch an entire video of you just saying "Einstein" the proper way.:)
So that’s why if you travel through space at the speed of light, no time passes. You’re moving at the speed of time, my brain just convulsed
Here's another perspective that might twist you up even more. Imagine that spacetime, is flowing past us at C. Assuming that celestial objects such as stars and planets etc, have some degree of friction or drag on spacetime, doesn't this then explain why we only move forward in time? Or to put it another way, what if we are being dragged forward through time by the flow of spacetime past our position.
She’s explaining it, but confusingly. We don’t move through space at the speed of light. Moving through time at the speed of light is just to say time passes. Nothing in the entire universe is truly stationary, quantum uncertainty principle. General Relativity explains it, but the implications are completely perspective altering. Time as most of us think about it doesn’t exist at all
@@elgaen555then neither does movement. There is no relative truth hence there is nor relative movement. If time is an illusion then so is space and movement.
@@ditchweed2275 why would you think that it’s connected in this way? Time as we think of it is an illusion we proven this, space time is a concept that we all have trouble conceptualizing. However it is very real
@@elgaen555 it's a phillosophical debate as to what is real and what is not, what underlies perceived phenomena and so forth. Like watching a magician perform tricks. What does real mean. But logically, Truth is not relative. There is no realative truth, hence since motion is relative, it cannot be true as in true motion. By relative I mean everything is related to everything else in a causal way. There are no isolated systems and since the sum universe energy equals out to zero then your perceived movement must be a sort of illusion.
This reminds me of (and seems to align with) an explanation of time dilation which goes as follows: We are always moving at exactly "the speed of light" in 4-space; when stationary in 3-space, that speed is purely in the time direction; as we move faster in 3-space, our velocity vector rotates out of the time direction. At the speed of light in 3-space, the 4-velocity will be rotated entirely into the spatial dimensions and the time component becomes zero. When you think about it, this explanation also explains why faster-than-light travel would be impossible, or would require movement backward in time.
"and since we experimentally know that the particles of light are to a very good precision massless": that's physics!!!
@Roger Loquitur With my eyes open I usually see around 400 million photons per second. Hallelujah!
Hi Sabine ~
Your videos are always very clearly and simply expressed. As a theoretical physicist I’m very much impressed by the way you can put across even complicated aspects of physics to make them understandable to non-specialists. But I object to this video. The idea that “we travel through time at the speed of light” is misleading and _not_ helpful to anyone trying to understand Relativity. Any object follows a “worldine” and its “speed” is just the _slope_ of its wordline in a (x,t) diagram. ds/dt is not a “speed!” That’s why ds is called an “interval”; it is _not a “length” or a “distance”._ At least, the video demonstrates the symbol-juggling that misleads some people (even people “with PhDs”) into making the bizarre statement that “we travel through time at the speed of light”!
Anyway, keep up your excellent work. I enjoy your songs, too...
Best wishes
~ Eric
Ed Catmull?! Holy sh*t if he’s the Ed Catmull, he’s super famous in 3D animation circles. Greetings from a long time practitioner and long time fan!
I was about to say the same thing. I guess it wouldn’t be surprising that someone like Ed would watch this channel though. 🤷♂️
Also, it makes me feel better that somebody at that level also has questions about this stuff. Makes me feel a bit less inferior. 😏
Now if John Carmack sends in a question...
Bob Burrough and co-creator of the Catmull-Clark subdivision algorithm!!
You all beat me to it!!
I’ve seen him reading around the palo alto area...seems like something he’d read/ask. Right?
Sabine, I thank you for the mathematical definition of the present of the presence ( relatively to oneself ). I like you.
I LOVED this explanation!
And the dress, but that’s said too often.
Nothing wrong with reporting a factual observation, Manuel :). The good lady explains things well for we laymen and dresses well as she does it. So she hones the mind and pleases the eye simultaneously.
The more I listen to Sabine my consciousness gets enlightened more❤️
So this has a practical application when you need to correct the small General Relativity errors when you are using a GPS map app in your smartphone while traveling in your car to arrive correctly to you destination but you cannot intuit this directly otherwise in our day-to-day experiences.
But is that due to gravitational effects? Or is it because the satellites are moving 17,500 mph faster than us? Maybe a bit of both?
@@mrcuttime22 Yes, although this effect on time can be worded as time-dilation, which is time slowing down or speeding up when close to a large mass such as a planet due to warpage of space-time. We are not normally aware of this strange, non-intuitive effect. Gravity can be thought of as distorting the space-time fabric as it would if you placed a bowling bowl on a trampoline.
Very interesting. I'd always intuitively assumed this was the case, but to go through the maths and prove it was enlightening.
So, reading between the lines, c isn't just the speed of light... it's also the rate of causality?
Basically, yes. Another way to put it is that c is the fundamental relationship between space and time, and is invariant for all coordinate transformations, ie, frames of reference. Einstein elevated that relationship to the status of being a natural law, which is also known as the Invariant Spacetime Interval. In that sense, the "speed of light" isn't about light, per se, but that Law of Nature.
Basically, c is the CPU clock speed of the simulation we are all in ;)
@@DavidPanofsky That's not true. A simulation would be unaware of the clock speed of the CPU. An algorithm is substrate neutral.
I remember having to derive this in my undergraduate relativity course. This video totally brings me back to my college days
Q: "Do we travel through time at the speed of light?"
A: "Yes."
Now go outside and play.
Nah. That's not true. All objects in Spacetime are fixed to the Universal Constant of (c) in their respective spatio temporal locations. Remember motion is relative. If all objects in Spacetime are fixed to the Universal Constant of (c) then that is the same thing as saying all objects are fixed and stationary in Spacetime.
Travel.
Thak you very much being a high school student I got the question "being wave how could only light travel through vaccum and not sound" which introduced me to relativity. Thank you for answering one of the big question that arised in my head.
Travelling one does with the mind. Perhaps get clear the time/space/movement constant.
Ed Catmull getting his name in big lights. How much did that cost?
I noticed the name, too! But I don't think I could have come up with as smooth a joke about it as yours.
If you really want to know, he offered to pay for an answer. I suggested he instead donates something to charity. Which he did (or at least he says he did).
@@SabineHossenfelder How much to get Sabine H. to "answer a question"? (Asking for a friend.)
@@arirahikkala I detect sarcasm, young man. Watch it! You don't have my life experience to be able to lay claim to being just as sarcastic.
@@JohnVKaravitis It's not a matter of how much you are willing to pay, it's a matter of asking a good question, one that (a) is interesting to other people too and (b) that I can actually answer. I don't have time to respond to all comments/feedback I get here and on other social media, but I certainly do take note of questions and suggestions. So, please keep the questions coming.
Another brilliant and clarifying video on a complex topic, thanks!!
The space-time interval is a concept that facilitates our understanding of SR, it's not something real in the world. So ∆s/∆t = c is meaningless. For the nature of time see: vixra.org/abs/2004.0278
I would have to disagree with that statement. The Invariant Spacetime Interval is quite real, in that it is the fundamental relationship of space and time which is a Law of Nature. It is as real as it gets.
@@kenlogsdon7095 I'm not disputing the invariance of the space-time interval. Read my paper.
The velocity of light is the same and equal for all observers which means that it conforms to a principle of objective democracy or proper 100% democracy!
The velocity of light is independent of the observer's 'perspective' or 'position' which means that it puts all observers in the same state. Tensors are frame invariant transforms they therefore conform to objective or ideal democracy!
All objects fall at the same equal rate (acceleration) in a gravitational field -- Galileo, gravity is the same for all observers -- objective democracy.
Absolute time (Galileo) is dual to relative time (Einstein) -- time duality.
Space is dual to time -- Einstein.
Gravitation is equivalent or dual to acceleration -- Einstein's happiest thought, the principle of equivalence (duality).
Energy is dual to mass -- Einstein.
Dark energy is dual to dark matter.
"Always two there are" -- Yoda.
Objective democracy is the scientific definition of democracy! Democracy is dual, objective is dual to subjective. Duality creates reality.
@@hyperduality2838 *"Duality creates reality."*
Indeed. Hawking pointed out that at cosmic t-0, matter and spacetime emerged together, the positive energy fermionic/bosonic hyperplasma emerging along with the negative energy hyperinflating spacetime with a net cosmic energy of zero (the interaction between mass-energy and spacetime, commonly called gravity modeled as spacetime curvature, can also be described as a positive energy matter/negative energy curvature situation).
Matter and spacetime are existential opposites in some deep sense, the ultimate yin-yang of physical Reality. For, you see, nothing can exist unless its opposite in some way also comes into existence. (This lies at the very heart of every conservation law, symmetries, Noether's Theorem, etc. The reason infinities explode in everyone's face when trying to quantize spacetime/gravity is because they're trying to force something to be its existential opposite. That, I believe, is the central issue that needs to be resolved, not trying to quantize spacetime into bosons.)
A more fundamental underlying relationship between big-R Reality spacetime/gr and Big-R Reality matter/qm must exist. If a modeling formalism could be found where R(gr)=/R(qm), the grand unification would likely be accomplished.
@@kenlogsdon7095 Do you accept or understand the idea that the laws of physics (all of them) are fundamentally democratic? There is a scientific definition of democracy therefore based upon the laws of physics and such a concept is hardwired into reality. The force of gravity is literally the same for all observer everywhere -- democracy in action.
Symmetry is dual to conservation -- the duality of Noether's theorem.
Positive curvature is dual to negative curvature -- Gauss, Riemann geometry.
Gravitation or curvature is dual.
Potential energy is dual to kinetic energy, gravitational energy is dual.
Energy is dual to mass -- Einstein.
Dark energy is dual to dark matter.
Space is dual to time -- Einstein.
Certainty is dual to uncertainty -- the Heisenberg certainty/uncertainty principle.
There is a pattern of duality which exists in physics! The question then becomes what is dual to entropy? Questions are dual to answers. This pattern also exists in philosophy.
Syntropy (prediction) is dual to increasing entropy -- the 4th law of thermodynamics.
Syntropy means "a tendency to converge", entropy means "a tendency to diverge".
"Through imagination and reason we turn experience into foresight (prediction)" -- Spinoza describing syntropy.
Syntropy is the process of thinking and using rational thoughts (logic, logos) to create optimized predictions which are used to track targets -- teleology.
Teleological physics is dual to non-teleological physics.
Randomness (entropy) is dual to order (predictability).
Using duality I have a created a new law of physics -- the 4th law of thermodynamics!
The concept of objective democracy (duality) leads to new truths.
Love this. Barely understand a bit of it but I want to replay it to try again.
Reads title : 😮 woah..
Now I'll be saying slow down to everyone, completely out of context, then giggling and nobody would even know wtf I'm on about.
( I'm a fan of Preter from family guy)
I will have to get used to saying a new answer,
"In spacetime." instead of "In time."
to the question
"When will we be there?"
I think the confusion comes from the concept of time dilation which says that clock would not seemingly tick as one travels the speed of light. I remember it imagining like teleportation but everyone not onboard gets old.
Cool that there is clarification between time and spacetime. Thank you Sabine.
plotting them on a graph, time as y space as x, you can imagine the gradient of the line is the speed. So max speed 'C' is totally flat and no movement along the time axis.
@@jorgepeterbarton I remember plotting like that in my relativity class. Seems you're right because I remember that a light particle makes a straight diagonal line ( forming 45 degree angle from both space and time axis if normalized units were used). And indeed if we take gradient (dt/ds), it would be c (or normal unit 1, for us who took basic relativity class). The gradient is constant and thus flat if plotted against time.
Thank you for reminding. Now, I have more intuitive sense of these concepts graphically.