Apparently if you built a train track around the planet and got it close to light speed, in about a day of riding the train you would get off and be in the year 2150. This seems like fake news. But if it's true, why dont scientists simply build a small donut shaped vacuum chamber with a capsule and a note in it saying, 'We are from the past, if you invent time travel send someone to 2022 and say hi'.

The vacuum chamber doesn't even have to be big, infact smaller would be easier as less energy needed. Then just blast the thing until it reaches close to light speed, and apparently it will stop in the future. In theory even half light speed would cause some time travel so its entirely possible.

Didn't read

Light speed is a measure of distance, not time.

If you travel at light speed time stops for you and increases for everyone else so you time travel, its basic physics taught in junior high

No one could handle that speed even if someone could I doubt it would speed up time.

Not true. The earth is moving something like 70k miles an hour. The issue is acceleration. If we slowly accelerate to speed of light, humans can handle the speed. The G forces of acceleration are what hurt. Think like the boiling frog experiment.It's relative but I'm not a physicist who can explain it.

https://en.wikipedia.org/wiki/Time_dilation

When traveling with the speed of light time does not "exist". Well sort of. If a body is traveling with the speed of light its origin and destination are one and the same. The question has no point because traveling with the speed of light means you have always been and always will be traveling with the speed of light. Of course from the viewpoint of an observer the speed of light is a defined number, but for a photon time is not a "thing". So overall it wouldn't freeze so much as stop existing.

https://www.popsci.com/science/atomi...-dilation/?amp

According to relativity, time slows the faster you go as you approach the speed of light. Gravitational fields can cause the same slowdown, too: The stronger the field, the greater the time dilation. Take Earth. The closer you are to Earth’s center the more Earth’s gravity is pulling you down, and the more time dilation you experience.

In fact, you’re experiencing time slower than birds above your head, and the stuff under your feet is actually experiencing time slower than you are. Earth’s core is actually 2.5 years younger than Earth’s crust. That might sound like a lot, but against our planet’s 4.6-billion-year-long history, it’s not even a drop in the bucket of time. Yet scientists have been measuring these kinds of subtle differences for decades, using everything from gamma rays to radio signals to Mars to, indeed, atomic clocks.

In 1971, two scientists carried atomic clocks on board commercial flights and flew them around the world, one in each direction. They measured a subtle difference of several hundred nanoseconds, matching predictions. In 2020, scientists used two clocks, one 1,480 feet above the other at the Tokyo Skytree, and found a difference that again proved Einstein correct.

These experiments show relativity is universal. “It’s the same everywhere on Earth, basically,” says Alexander Aeppli, a graduate student at JILA and NIST. “If you can measure one centimeter here, you can measure one centimeter somewhere else

bruh never heard of Super Man?

You're missing the point.
So you build a vacuum chamber in a donut shape the size of a tennis court. You put inside a tiny capsule with a note in it saying we are from the past etc. You then accelerate the capsule until it reaches somewhat close to the speed of light, maybe just 70% light speed. The capsule in theory will now travel forward in time hundreds of years over the course of several days. When you turn the chamber off does it just stop existing because it's in the future now? Where does it appear for people in the future?

Those experiments show that there is an imperceptive difference in the clocks.

I could never understood this concept.

If you travel faster, say like quicksilver, I suppose everyone is very slow relative to your perception so it looks like you slowed down time.

But did you really? All you did was travel faster than the rest, time still moved forward as it always has.

Let’s say you’re so fast you reach the other side of the world in 1 second, technically you done so much and it almost seems like time paused for you, but it didn’t, all you did was travel fast enough to get there in 1 second. Now travel 10x the distance and it’ll take 10’seconds, time isn’t slowing down much less reversing.

If it takes light 1 day to reach a far away galaxy and you travel slightly faster than light in a race to that galaxy, wouldn’t it just mean you arrive there before light and it’ll be dark when you get there and light won’t have reached you yet.

I guess I can’t truly understand the concept of time. To me it’s something that’s always moving forward. Everyone can have different perceptions of it but it’s moving forward nonetheless. If time is the process of micro events happening in sequence, why would moving very fast reverse that sequence of events?

Im guessing it depends what the people in the future will do with it ? For example if nobody touches it it will come back as usual but with significant aging but if something happens to it in the future it will disappear. But there are a lot of variables. What if in the future the camber breaks or happens something to it ?
Wait and what happens if someone from the future enters the capsule and you stop it ?


After thinking about this for a while like you can see above I think the answer is you can only travel forward in time but not backwards, If you accelerate it like you said in that chamber it disappears but how does it reappear somewhere else ? because in the future there is already one of those so you will have like 2 capsules ?
Wait so IF we leave it be, we (the present ) have one capsule and the future has the same capsule, but in the future, so everybody has 1. IF we fiddle with time like you said and send it into the future THEN our capsule from the present will DISSAPEAR and the FUTURE will have 2 capsules ( one from the past ( from our present ) and their one ( the one from the future ) ! I think this is the answer. But without the posibility to send it back in time, only forwards.

Edit: And how i think it will happen ? It will just appear somehow, like in the cartoons where it pops into existence. Also, we have not yet experienced this because look at our past, nobody will try this in the past because they are not capable. THE PAST has not reached that point YET.. What will be interesting is at the moment in time we figure out how to do time travel in the future, the PAST WILL TRY IT and then we ( the future we ) will see the past we try time travel.

For example lets say we figure time travel and send a pen 10 minutes into the future. It will pop out of existance and AFTER 10 minutes the future us will see that pen.


Can someone confirm my thought process please ? ayy

See, it is thought provoking and I cant think of any scientist explaining that one. Seems impossible tbh maybe I should contact Neil DeGrass Tyson

read my edit post, that is the only way I can see it happen and im pretty happy with that answer

Edit: And how i think it will happen ? It will just appear somehow, like in the cartoons where it pops into existence. Also, we have not yet experienced this because look at our past, nobody will try this in the past because they are not capable. THE PAST has not reached that point YET.. What will be interesting is at the moment in time we figure out how to do time travel in the future, the PAST WILL TRY IT and then we ( the future we ) will see the past we try time travel.

For example lets say we figure time travel and send a pen 10 minutes into the future. It will pop out of existance and AFTER 10 minutes the future us will see that pen.


Can someone confirm my thought process please ? ayy

brb trusting that tradies like dogorman built the train structure strong enough to never break while you're going near speed of light.

brb trusting no one is going to fk with it while your on it

brb could just get in a space shuttle and orbit the earth with far less energy

But wut if the planet/disk is spinning at the speed of light in the opposite direction as the train?

Read but didn't understand a thing.

Maybe I am too tired

Special relativity.

We've known about this since 1905 brah. Time is relative, the perceived passage of time depends on your reference frame. We experience time on earth roughly the same because we are in the earth's reference frame. Time dilation and length contraction (since you also experience length differently at different velocities) can be calculated using the lorentz formula, it's a predictable, deterministic linear equation.

You're not 'travelling to the future' as such, you're taking a different path through spacetime and experiencing time differently to other reference frames. It's effectively the same thing though.

Sooo what happens to the capsule

I've only skimmed the thread, what's the question?

How are you going to power something to achieve and maintain that speed?
What happens when something traveling at that speed collides with something?

It ignites the atmosphere and blows the Earth up

That or you hit the fast forward button on time for everyone else

You're misunderstanding how relativity works.

First of all, even a capsule would require an enormous amount of energy to accelerate close to the speed of light, anything with sizeable mass would but i'll let this slide. Accelerating mass to the speed of light itself requires infinite energy.

Time dilation is only really significant at speeds very close to the speed of light, we're talking like 95%+. At 70%, for every 1 year in the capsules reference frame, 1.4 years passes in the humans reference frame.

So what this would mean is, at 70% of the speed of light, for every 1.4 years the humans are looking at the capsule, the capsule has 'experienced' 1 year.

So for example, if the capsule had some strawberries in it, and it travelled very close to the speed of light (like 99.9%), the observers would see it travelling for a much longer time that it experiences, so they may watch it for months and when it stops the strawberries could still be ripe (depending on the reference frame), as the strawberries would have experienced much less time than the observers looking at it. Nothing 'travels to the future', different reference frames experience time differently depending on their velocity. They also experience length differently, known as length contraction. Time dilation and length contraction together are what ensures the speed of light is a constant from all reference frames, even though velocity is a relative property.

In your scenario, but with say 99.99% of the speed of light, the capsule itself may experience seconds, but to the people outside it's been travelling for hundreds of years.

Lose the notion of 'absolute' time, and this becomes easier to grasp.

It means 299 792 458 m / s

m/s = speed



It can be used as a distance (light years) but... mph can be used as a measure of distance too.

If we talking about 100mph, then 1 hour means 100 miles.

If we are talking about light years... we are talking about 670,616,629 mph so... 1 hour = 670,616,629 miles.






Right? (I mean... I'm not a physicist)

TappingTheZen's response above is on point.

If you shut down the accelerator, removed the capsule, and destroyed the note after a few days.....the note wouldnotexist several hundred years into the future or anything like that. It never got past those few days! That's now how time dilation time travel works.

What did happen is the note aged very little during that time, assuming its speed was high enough. See the segment starting around 3:25 in that video in the OP. From our frame, looking at this capsule whizzing around the tube, we would see the time appear to move slowly for the note. I like Zen's example of the strawberries better because the effects of aging are more obvious than a written note. But the point is if you shut down the whole thing after a few days, whatever was in that capsule barely aged at all, and yet coming out of there, it would be a few days later in time on earth, a surprising result. But not hundreds of years into the future or anything like that. It would just be a few days into the future, but a less-than-that aged note.


Now if the apparatus was running for hundreds of years (somehow, and for some reason), and then shut down, someone hundreds of years (say 300 years) into the future could extract the note and see what it says. But this wouldnt be some kind of surprising result to them: to them, it was just a note whizzing around for hundreds of years in a tube, and then extracted. It wouldnotbe as if some mysterious note appeared out of nowhere, from the distant past. Actually this wouldnt be much different than if the original scientists just wrote a note, put it into a time capsule, and then stuck it underground, to be unearthed in 300 years. There is one noticeable difference though....the note in the ground aged 300 years while the note whizzing around in the tube aged a lot less than that.

Reminds me of Han Solo bragging about making the Kessel Run in a certain number of parsecs.

c is a speed, not a unit of distance or time.

Technically it's not a measure of anything....it's not measured! The speed of light in vacuum, c, is defined to beexactly299,792,458 m/s, it is a derived unit. Because of how units were defined by convention in 1983, a meter is no longer defined as the length of a platinum bar in paris, a fraction of the circumference of the earth, etc, etc....it's defined as the distance light travels in vacuum in 1/299,792,458 of a second (a second being defined separately). With that definition of meter in place, and knowing that the speed of light in vacuum is constant, you know what the speed of light is without conducting a single experiment to measure it....it has to be 299,792,458 m/s. (notice the exact integer with no decimal....that would quite the remarkable coincidence if a meter was for example a bar of platinum in paris). The meter, on the other hand, is somewhat tricky to actually realize in reality. When someone says they are "measuring the speed of light", they are really "measuring the meter".

You’re thinking light-year, you clown lol.

Light-year is the distance light travels through a vacuum in a year.

Accelerating a train to even 1/1,000 the speed of light would require a rediculous amount of energy. Far more energy than humans will ever produce for our entire existence combined. The closer matter gets to light speed travel the more massive (heavier) it gets. That's why it's mathematically (physically) impossible for any matter, even an electron, to travel the speed of light. It's mass would eventually approach infinite and require more energy than the entire universe to accelerate any further.

This is they key to making sense out of how it's possible. Obviously it's more complicated but in simple terms, the universe slows down time and contracts the distance of objects relative to each other so that the speed of light is ALWAYS measured the same no matter what your reference point is.

Even if you're traveling 99% the speed of light, when you measure a photon it will still be travelling at 100% the speed of light, not 1% as you might think since you're already moving at 99% light speed. The passage of time and distances contract so that photons will always and only travel at light speed. Everything else is relative.