Do we travel through time at the speed of light? 

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

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. :-)

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?

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?

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.

"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

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!

You just fancy her! Admit it Sir!!

@@DeadlyKiss000 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.

should be plus, it's hyperbolic

"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

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).

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.

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?

it's impossible to go back in time, you would theoretically have to travel faster than the speed of light, but that's impossible since the faster you go the more energy you would need to accellerate further, you would need an undefined amount of energy to exceed the speed of light, maybe if you had negative mass you could, but the speed of light is a constant in which we all find ourselves into, if we go fast, we travel slower through time and if we stand still, we travel faster through time, so we are bound to that c constant (if I understood well)

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

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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-944y9HlLmqw.html

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.

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.

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.

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.

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.

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?

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.

Travelling one does with the mind. Perhaps get clear the time/space/movement constant.

There's also a part of your brain dedicated to flagging things to you that are relevant to what's on your mind.

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?"