In the faster than light world, everyone says you can't go slower than light.

The was a woman named Bright Who flew at the speed of light She went out one day, in a relative way And came back the previous night.

I am 55 years old and your explanation / analogy of the why we can travel faster than the speed of light was the best I have ever heard. Your caveat concerning the shortcomings of the analogy were most helpful as well.

Why didn't anyone ever explain this to me? Seriously, it took him 8 minutes. I'm seventy f##king one and no one has explained this little fundamental, essential piece about motion through spacetime to me before. Suddenly a lot of other things are much clearer. Damn. Thanks, Prof Lincoln, you're a star!

Einstein's girlfriend, "I need two things from u space&time Einstein-"Okay what's second"

The conclusion seemed to be, you can't go faster than the speed of light because the speed of light is the fastest you can go.

I missed a large chunk of this at the start when I read the email, "I am a Nigerian Prince"......just lost it slowly but surely.....thank you for that Sir!....(..& G'Day from Bunbury , West Australia). Keep up the excellent work....clarity is much appreciated!

Sir, THANK YOU!! I find this topic very hard to understand.... Or did, until I came across your video. You've made it so easy to understand, and I find it intriguing. Thank you so much! 🙌🙏

When you hear "just trust me on this" you know quantum physics is being discussed.

0:54 So y'all not gonna talk about the Nigerian Prince in the e mails? 😂😂😂😂😂😂

I wanna say thank you so much for saying this in a clear way, I ve seen some videos on this and they couldn't really explain it well to me

By far the best and simplest explanation of relativity and the connection of space and time I have heard. He knows how to get to the core of the subject. Good job! I have become a fan!

... That was a complicated way of saying, that you can't go faster than light because you can't

“I am a Nigerian prince” in your email. Nice 😂

Both the notion of space-time and the abstraction explained here are mathematical tools to better illustrate and package the concepts contained in the theory of relativity. Even though I appreciate the simplicity they bring to the subject, it is perhaps a bit of a misrepresentation to claim that an abstraction constructed to simplify the concept is the reason that the concept works in the first place. To expand a bit on the topic discussed in this video, I should say that we have no notion of the speed at which we move through time so to say that when we are at rest then we move through time at the speed of light is an artificial idea that makes sense only in the context of trying to find a framework to make sense of relativity, and so to claim this constructed concept explains why you can't go faster than light seems wrong. Neither spacetime nor the Minkowsky abstraction explain relativity but rather are mathematical abstractions to simplify visualizing the consequences of relativity.

Its Good to see the many responses to this topic !!!!!😀 . Its through discussion of ideas that we refine our theories . Its strengths and weaknesses .

0:55 "Alpha Centauri is easy" "The New Einstein" "Relativity is an Illuminati plot" "I am a Nigerian prince" LOL

Ahhhh 🤔 So that's why when I go for an hour long run, time only shows 5 minutes have gone by

It took me a long time to get this one, but it blew my mind once I got it! Thank you!

The question posed for this video is " why can't you go faster than light?". The answer included the idea that our movement through space time is constant, and we really don't know why that's true. Maybe I'm missing something but that doesn't explain anything in my mind.

The true theory of relativity is this; If you're a millionaire and you die without a will, you'll suddenly have more relatives than you dd when you were alive.

Love the "I am a Nigerian Prince" cameo in the gmail inbox! 0:55

I've been told that the reason is, that as you move faster, more energy is required for increasing the velocity. Then at the speed of light, assuming you'd ever get there as a non-massless object, the amount of energy needed to accelerate beyond the speed of light would be infinite. And since we could never have an infinite amount of energy, we couldn't ever reach the speed of light, let alone go beyond it. Is this incorrect or just another way of looking at it?

This is by far the most visualized and easy to interpret explanation of time dilation and why time cannot be exceeded and it explains the deeper reason behind. Most of the explanations I got is just mass increases and cannot be infinite. In my opinion, speed of light is like video game’s pixel loading speed

My bicycle can't go faster than light because it's two-tired.

"There was a young lady named Brght Who travelled much faster than light She took off one day In a relative way And came back the previous night"

I remember about 11-12 years ago there was this major story in science about how at CERN they had supposedly discovered neutrinos that move faster than light. I never got all the details of the story, but from what I recall, it’s turns out a wire was lose somewhere, which caused this reading, and a number of scientists became embarrassed from having supported this finding (Don’t know if the last part is entirely true though)

It's not tool late to find this out ! thanks for the great job you are doing on this channel

The email part has to be fake...it's so perfect This guy is better at making memes than all of us

I think that my car goes faster than the speed of light because when I turn on my headlights nothing happens.

The travelling car analogy is perfect. So easy to visualize Space x Time when thinking of it as North & East. Now, what if you threw the car in reverse??? hmm....

Outstanding! This was a very nice, and simple to understand, high level explaination for why we can't move faster than the speed of light. Although you didn't get into some of the more intriguing and exotic characteristics of this question, I appreciate how well you were able to convey this information so fast, efficiently, and understandable to anyone. I'll look forward to viewing your other video presentations.

As a person who dropped out of high school to work, then in later life started to enjoy finding out about physics, I have to say, your videos are always ( mostly 😊 ) easy to understand, I just wanted to say thank you for another great explanation! Slainte 👍

I'm glad he moves his hands with every sentence, it really makes the information clearer.

This was way more clear than most of the fancy flashy pop science channels. Thanks

The clearest explanation yet. I was blind and now I see. After hearing you everything else just fell into place. Thank you

“I’m so fast that when I turn off the bedroom light, I’m in bed before the room gets dark.” Mohammed Ali

This video: "Why can't you go faster than light?" Up next: "How to travel faster than light" huh

Thanks. If v > c then the Lorentz factor is complex. Does this possibly mean that if we could jump to a velcoity v >c (maybe not through typical acceleration which would never exceed c), we could move out of space time and maybe into something inbetween it. I guess my thought was that this might be similar to the >c jumps in star treck. Based on travel between space-time, we could emerge at other points in space-time with little or no difference in the actual change in time within space time. So a complex time might mean that time exists in more than one dimension, or that there is a complex addition to space-time. Is it possible that sub-atomic particles might be able to make these jumps? So changing position without observation?

I was thinking the same thing the other day and then I thought: If I was traveling at infinite speed. My line would be vertical on the graph. Which means I would not be moving at all because my position on the x axil stays constant. Which is counter intuitive because if my speed is indicated by the slope of the line and a vertical line has no slope. Which means I have no speed. I am stationary. However I could not tell if that was the speed of light. Because if the slope of the line indicates speed. The slope of the line would be determined by how I decide draw the scales on my graph. I would know how much I have traveled because we can measure distance. For the sake of argument, if we rule out relativity at this point which means we think our meters don't change no matter how fast we are moving. I wouldn't know how time is flowing faster or slower. I wouldn't know if my watch is working properly. How could I tell if it was? How would I know if the vertical line indicates the speed of light? This bothers me because there is indeed a speed limit in this universe but it could be whatever I wanted it to be? This didn't make a lot of sense. If I draw the y axil longer all the lines on the graph with the same slope would indicate higher speed.

I think the explanation on PBS spacetime was satisfying as well. It explained the speed of light was actually the speed of causality. Its the quickest speed that anything can react to anything else in the universe!

0:55 the infamous Nigerian Prince strikes again...

Wow, great explanation! first time I've heard it explained this well

Thank you for the explanation! Now I am going to watch your video titled "How to travel faster than light." 🙂

I get it now. Thanks for not going too fast. I needed a moment for it to sink in. The graph and car analogy helped tremendously.

This is excellent. Thank you for making this topic accessible to regular folks like me.

In the beginning I thought this was going to be another video I would not understand but you explained it well.

A very nice explanation, but now I have another question. Why is every object moving through spacetime at one and only one speeds? What determines this boundary?

"The faster you move through space, the slower you move through time" Ah, so that's why an hour always lasts a year when I'm exercising...

Even if we sit in place, aren't we moving with great speed across space, along with earth, sun and milky way?

That was the first time I even thought I had any idea what "space-time" meant, amazing. Duly subscribed, thanks!

Excellent. And for some good visualizations of this (without the math), I suggest "We all move at the Speed of Light" by ScienceClic English, also on the Tube. And for lots MORE math, there's "Do we travel through time at the speed of light?" by Sabine Hossenfelder.

Diarrhea is faster than light... in fact, i didn't even had time to turn on the light.

I like that I am travelling at the speed of light through space time, even when lying in bed watching this on my iPad.

What we learned way back in 1970 was that a small portion of our SPEED was converted to mass, and even with a slight portion of mass involved SOL was then unobtainable. Since I am just a biologist, musician and such and NOT a physicist, things may have gotten further since then?

sign of a good theorist .. able to convince everyone that they understand fully his theories

THIS is the kind of explanation I've been looking for. Much appreciated.

Title: "Why can't you go faster than light?" Video: Ya just can't, trust me.

Here is my question: this explanation is great, but if I am correct it is based on assumption that we move through spacetime at the speed of light. But why at that speed and not, for example, 0.8 x speed of light?

This is great, and technically correct relative to the title (the best kind of correct), but doesn't really explain why you can't go the speed of light. In fact, it implies that you CAN go the speed of light.

In the year 2500, I went faster than light in an experimental machine. Turns out it made me go backwards in time and now I am stuck in the year 2021.

After years of study... your geometric diagramme (x;y) has finally made me understand spacetime and the connection between the two 😭 cannot thank you enough, you have achieved in a few minutes what Hawkings' book did not 🌷! Mathematics rules!!!

There is a difference between "We move through spacetime at the speed of light" and "The velocity of an object". What he doesn't get into is every particle, like a photon of light, that has zero rest mass travels through space at the speed of light. They don't experience time. If you have mass and want to travel at high velocity and slow down time from your perspective, you have to introduce kinetic energy to gain that velocity. But it gets to the point where the energy cost to gain momentum is simply too great. You have to keep adding more and more energy for less and less velocity the closer you get to the speed of light. Until finally you can't go any faster. That's the real reason all objects that have a non-zero rest mass cannot exceed speed of light velocity. You cannot violate that energy limitation. Which is a geometrical property of spacetime itself. Hope this helped.

Hi Fermi! for 18 yrs lived in Batavia right off Pine and Hart. My buddy next door was in charge of the LinAcc for 25 yrs, Duke Wahl.

You clearly have a deep understanding of this. You explained something commonly very confusing for people very simply. Bravo.

I saw this and laughed,it's impossible to go faster than the speed of light, you would be traveling in the dark and crash.

How to measure the one way speed of light. Use two clocks that are synchronized by an external tick. Use a cosmic pulsar to synchronize the two clocks. Put the clocks together and synch-up with the pulsar pulses. Move the second clock some distance away(D). During the movement, the two clocks stay synched up via the pulses of the pulsar. This negates any relativistic induced error caused by the movement of the second clock. Fire a light pulse that will be detected by the second clock. Bring the second clock back to get the difference in time(T). The two clocks are still synchronized by the pulsar, and have remained synchronized during the entire experiment. C = D/T

Wow, you just clearly confirmed what I thought was only my vague suspicion- that we're all hurtling through space-time at the speed of light..

There was a scene in the original Cosmos that disturbed me very deeply. A teenager leaves on his scooter for a relativistic tour of the countryside. When he returns, just a short time after he left, there is an ald man sitting where his brother was. Then they explained that the old man WAS the brother. I was about 10 at the time, and for some reason this had a powerful effect on me. They had the same sort of thing in a movie, but not quite as dramatic. In the movie this kid is sent out to bring his little brother home. The kids end up separated. The older kid falls and is knocked out. He come to some time later and goes home. The door is locked and he finds some other people living in his house. The police are called and they find out the kid was reported missing years before. He is reunited with his family, but his mother is much older, and his little brother is now a teenager, older than HE is.

Dr. Lincoln, thank you for that easy to understand explanation about the Speed of Light. Your example of North / East and the Vector the car is traveling makes sense. By substituting Space / Time, something that was hard to comprehend became much easier. I understand this new concept and will forever forget about increasing mass relative to speed as I was taught years ago.

it's possible I understand it better than I ever have from his simple example, good stuff

My theory, I call “Shell Universe” theory is; It’s because our entire universe is a shell around a black hole in a parent universe. Nothing enters a black hole because as particles reach the event horizon they become stationary in time relative to their parent universe, forming a sphere of mass around the black hole. A formation of a black hole and creation of this shell we call the “Big Bang”. All particles to exist within this shell have a common energy level which results in either a velocity or spin. Particles with low spin we perceive as light, although light particles with marginally higher spin have fractionally lower velocity/inertia hence are diffracted to a greater angle in a glass prism. Particles with high spin and low velocity we perceive as mass and form atoms, dark matter is just the stuff in-between we can’t see. Might be totally wrong though, so far my only taker on my theory is Murphy my dog and even then it took a bribe of several treats.

Thank you sir for remembering that not everyone is used to calculate in imperial system (SI is THE standard one...). You are very good in explaining difficult things for common people like us. I am a PE teacher with a passion for science and space exploration. Salutations from Italy, thank you.

I went faster than light but nobody saw me.

When I was 18, more than half a century ago, I postulated that the speed of gravity was faster than the speed of light. And this deduction made me think of how a spaceship could travel at the speed of gravity (faster than the speed of light). Here's how I deduced all this: I imagined that a laser light briefly turned on and off (pulsed), and that as the light pulses or beam moved forward it would be bent or otherwise distorted by gravity. In order for the pulses to be "captured" and distorted by gravity, the force of gravity had to move quicker than the light pulses could move. Therefore, gravity was faster than the speed of light. With this in mind, I imagined a round spaceship (a flying saucer) with a giant size gyroscope inside. I had a large enclosed gyroscope toy that had a crank to wind it up (instead of a pull string). I noticed that when I cranked it really fast, not only did it perform as gyroscopes do to balance themselves, but if I tossed the gyro up, it appeared to pause at the apex of the ascent - demonstrating an anti-gravitational characteristic. This seemed different than the mere tossing of a ball into the air, which I would say demonstrates no delay of any kind in switching from ascending to descending. I then imagined that if the gyro could spin fast enough that it would become anti-gravitational. I likened the force of gravity and anti-gravity to different magnetic fields (like and unlike fields), which would instantly (at the speed of gravity) attract or repel each other. The result would be that the flying saucer would have the ability to be repelled from, or attracted to, a celestial body such as a planet at the speed of gravity. From this, I had to work out how a flying saucer would be able to hover (not be instantly repelled completely away from a planet), how it could move gradually up and down, move horizontally, what could possibly power the internal gyroscope to reach its anti-gravitational speed. I presumed then, and still maintain now, that a nuclear-powered engine would be used, and that a computer(s) would automatically and rather instantly adjust the speed of the spinning gyro to keep the ship steady to hover, increase to ascend, or decrease to descend. Moving horizontally or diagonally would be accomplished by slight tilts in the balance of the ship which would act somewhat similar to how a sailboat can move forward against a wind by tacking. The tacking actions would be so instantly controlled by the onboard computers that the minute zigzagging movements would appear to observers as being in a straight line. I imagined that space travel would be possible by using the ship's anti-gravitational forces to repel from one planet or star towards another, and then ricochet from one to another - similar to how a ball in a pinball machine picks up speed as it bounces from one bumper to another. I imagined that any onboard computer(s) could chart the cosmic path and make adjustments at the speed of electricity (the speed of light). Moreover, I imagined that cosmic knowledge and "charts" would be used to best determine when voyages could be made in order to use closely aligned bodies to bounce from one celestial body, thereby shortening the distances, and perhaps even multiplying the speed at which the ship could travel - twice the speed of gravity, three times the speed of gravity, etc., etc. In Star Trek vocabulary, Warp 1, Warp 2, Warp 3, and so on. Somebody get Elon Musk on the phone! Any thoughts or criticisms?

1) This also explains why time-travel isn't possible. For objects to travel through time, they would need to be faster than the speed of light in order to arrive head light, which isn't possible. 2) As a geopolitical analyst, I can attest to the fact that ordinary people far from always exist in a world of broad knowledge, wisdom, and insight. And those emails you showed there... makes me chuckle, thinking of my own inbox and the hundreds of emails I get about why I am wrong or why people disagree. And 99% of the time, it is simply because of a lack of insight -- not always at their fault, mind you. We can only concentrate on and so and so much. And for most people work, job, kids, marriage is more than enough.

Thank you so much, Dr. Lincoln. Your videos are so helpful and have helped me gain a more complete understanding in some key and fundamental concepts in physics through the consistency of your presentations. I also love how you make sure to include other videos linking to the content in the current video. It's taking me down a wonderful rabbit hole of knowledge!

Excellent video. The simple fact that everything moves through spacetime at one and only one speed brings it all into focus. Thanks for that. Cheers, Russ

Such a cool explanation. Is there a video about General Relativity?

It's very possible that there are things that travel faster than light that we are not designed to perceive, similar to the wavelengths of light that our eyes can't see or sound beyond our capacity to hear,

This is one of the most interesting shows you've done! I like it. Hermann Minkowski's intuition was so insightful and so very important to put Einstein's theory of relativity in an geometric context. I've viewed this show twice before and several months later I viewed it a third time. On the third visualization I got an idea. I would like to offer an answer to your question: "Why everything in our universe is travelling through space-time at at the speed of light?" I offer the answer: "It's a quantic property of our space-time". This is reminescent of atoms absorbing energy at specific energy levels. This my speculation here. If we think of our space-time as a bubble in a super-space containing our space-time universe and possibly many other things that are hard for us to imagine. The only way to enter our space-time bubble is to have a specific level of energy (like quantic behavior of atoms). Conversly, one way to exit our space-time is to diverge from that level of energy. Black-wholes may be one example of diverging from our space-time universe's level of energy. I am suggesting that whatever is in black-wholes is outside of our space-time universe because what's inside diverges from our universal level of energy to travel through space-time at speed c.

Thank you sir. Very clear and wonderful way of explaining. Science is amazing.

Elsewhere I've heard it said that the Speed of Light would more accurately be referred to as the Speed of Effect, as it is the speed at which an effect occurs. (Assuming I understood it correctly and am remembering correctly)

Open to anybody ; How does gravity bend space ? How does gravity grasp a hold of space ? Physically . Explain further your thinking , in detail . On how this can actually happen .

0:55 "Alpha Centauri is easy" "The New Einstein" "Relativity is an Illuminati plot" "I am a Nigerian prince" -Dr. Don Lincoln

This is the first explanation that has made sense to me. Awesome video!

I think it's a truly convoluted explanation for something that should be simpler. Energy of a body is equal to its inertial mass (times c^2), aka, its energy content, plus its kinetic energy (1/2m*v^2, if v is small). Or in brief, it's its mass at rest times c^2 times gamma (the Lorentz function of the velocity), E=gamma*m*c^2. If v approaches c, the relativistic energy of the body approaches infinity, it grows unbounded. Meaning to accelerate a body to c you need infinite energy.

Any time there's a fixed propagation speed, there is a supporting medium, a carrier, of the wave. Whether air or water or solid, the medium is of a certain density which fixes the propagation speed of sound through it. So what is the carrier medium of light? What property of "space" fixes the permittivity/permeability value to what it is? Or is it just a fixed constant, a "law of nature" that we should never enquire about?

I've watched a lot of relativity videos (and taken a physics class or two) and this is the first one where someone mentioned that everything moves at the same speed through spacetime and "velocity" is just changing the direction of that vector. And OMG everything else suddenly makes sense now.

Since I am on my bed listening to your lecture, I was thinking that even though I am stationary relative to earth I am technically moving through space and time on a determined vector relative to the sun.

Nice explanation on the two directions of space and Time . I am still convinced that there is a density of space that keeps the speed of light (and Us) fixed. The M&M experiment seemed inadequate to explain it. I also have the crazy idea that some of the particles identified by physicists are just the peaks of combined waves in that density. Realizing that there were air particles that transmitted sound waves, that the waves in the ocean are energy waves (of many combined frequencies) transmitted by the water molecules (See Waves and Beaches - Bascom/Mcoy) are explained with simple experiments. Seems like there might be a simple experiment to show the density (material) of space. Sadly, I haven't thought of it yet. Thanks again Doc.

Hi Doc, I'm a bit late in the game to ask questions, but I totally understand the Time/Space Graph. Is the reason why light has a speed limit the same reason why a cloud cannot travel faster than the wind that carries it?

You can't fool me. I've seen every episode of Star Trek. The secret is to have a Scottish engineer.

Great explanation by Dr. Lincoln, as always. I am wondering if someone catched the funny touch of his inbox's message list (0:54). Very hilarious message subjects, including a nigerian scam prince letter! 😂

While I seem to be able to understand the connection between space and time on a fundamental level, I'm still not clear on limitations of time. Furthermore, I'm also not clear on how mass is used to determine whether or not we can move faster than light because it was mentioned but not explained in this video. Now, space is apparently infinite so I guess there's no limitations there, but the limitations of time seem to be directly linked to the limitations of speed through that unlimited space (to my understanding). And those very limitations, (again, to my understanding) are used as a basis to postulate theories of limits of speed through space since going faster than light would mean the time would start going in reverse. So far so good? Correct me if my comprehension failed me. My question is: why is it asserted that everything always moves at the speed of light? I suppose it's asserted in relation to time, but how do we know time has stopped for every single particle of light? Because that's what we would need to know to be absolutely sure.

Because of the related time dilation that occurs as matter and energy approach the speed of light, the forces under which matter and energy operate could no longer have enough of an effect, resulting in matter and energy literally coming apart at the seams, which is why nothing can exceed the speed of light.

Great simple visual explanation using an X/Y chart. Really cleared up my understanding of speed through time and space.

Physicists: "Faster than light travel is impossible." Aliens: "It is until you know how to do it."

This is exactly the explanation I was looking for

Thanks for a real cool explanation! Enjoyable video.