Time dilation is a serious problem for interstellar travel. A close trip to Proxima Centauri at 95% the speed of light would last around 4 months on board, but around 8 years would pass on Earth. If you go to Proxima Centauri and return it would be an 8 months trip to you but 15 years would have passed on Earth.
The greatest hope is that the energy problem in warping space-time is solved. If you get a ship that can warp space before it to a factor of 10, effectively traveling 10 times the speed of light, it could reach Proxima Centauri in 40 hours and only 40 hours would have passed on Earth as the ship isn't actually traveling at the speed of light but warping space-time around itself.
The problem is that only forming the warp envelope around a ship to reach this factor of 10 would require energy equivalent of the entire mass of Jupiter being converted into energy in a fraction of a second. If you want to know what kind of energy this means, just use the mass of Jupiter in kilograms to the famous E=mc2 equation... Trust me it's a lot of energy...
There are scientists dedicated to finding a solution to the energy problem, such as the Tau Zero Foundation, created by a former NASA physicist, but, as far as I know, nobody has found a solution.
Other proposed solutions such as artificial wormholes meet both the energy problem and the stability problem. Opening a stable wormhole would require both dark matter and dark energy and we have no idea how to generate, capture or store them.
@shandyr Time dilation happens because a body with any speed distorts space-time around it. I would have to go into Eintein's theory to explain, but it's one of the effects we know to be true. The entire GPS, for instance, has to compensate for time dilation of the satellites relaying signals back to Earth.
My biggest problem with time dilation is the idea that every observer has their own clock so to say.
I had always assumed that the passing of time was constant and the same for everyone.
This does not seem to be the case though. And I'm having a hard time to accept and understand that.
That's pretty much THE key idea of Einsteinian relativity. It works because it has to, because the speed of light is a constant however the observer is moving.
That's more of a "what" than a "why". The BBC* did some documentaries with Prof Brian Cox (who I was at uni with) that explain the reasons and implications of relitivity without going into the maths.
That's the beauty of it. That we are able to discover the Universe is not at all what we thought it was and can use that knowledge to our own advancement. GPS would be impossible without knowledge of relativity, the computers and phones we use everyday rely on some properties of matter related to quantum physics and so on...
For a long time, us weird apes had a whole buncha cultures that saw an intuitive, easily graspable objective thing in the sun rising, moving across the sky, and setting. The sun traveled around the Earth! It must have!
Luckily for us, some even weirder apes realized the counter-intuitive was actually true and the thing which intuitively followed from our basic sense perception was, in fact, an illusion. We were the ground which was spinning, but feet firmly planted don't register that motion, and conspire with eyes to fuel the subsequent illusion.
A lot of stuff is like that, it turns out. Feeling oneself at the center of something often makes the things outside seem mappable to that backgrounded, ignored default...which is more often wrong than right. Time and space are no exception!
I have a question for you smart people, how can someone create this calculation and prove it's correctness?
Is the time dilation per % of lightspeed an approximation or is it proven? It seems.. too perfect that it's exactly 10x to 100%. And what does 10x mean? In the text it seems there are time dilations higher than 10 times the normal earth speed of time.
Unrelative to the thread, but as an FYI - been listening to space ambient music for a couple of days now and been thinking alot about 'space'; the size, our little planet and what it would feel like to ride through the vast, empty space alone on some space ship.
The math involved is way over complicated to be briefly explained in this thread. Proving it wasn't easy either. One of the experiments involved two atomic clocks one on land and the other in a high speed vehicle. The difference in time measured was compared and was within prediction.
The derivation is a little long to post here - I have a 286 page textbook in front of me (and that presupposes A level Maths and Physics). However, I can explain where it comes from.
Like all proper science, it starts with an observation. In this case, that when you measure the speed of light you get the same answer, irrespective of how you are moving when you do the experiment. This cannot be explained using the laws of motion calculated by Isaac Newton. If you want to know how the original measurement was made, look up the Michelson-Morley experiment.
Since speed is equal to distance divided by time, for the speed to remain constant, distance and/or time must change with the motion of the observer.
How we know it is correct is in it's use: if we used Newton's laws to calculate the position of satellites, GPS wouldn't work. With Einstein, it does. That doesn't mean it is absolute truth though. Science doesn't peddle "Truth". It works for all the observations we can make now, but there many be observations that we become able to make in the future that mean that the theory has to be modified. Newtonian mechanics still works perfectly well for pretty much any every-day life situation.
As for the limits of time dilation, as you approach the speed of light, the rest of the universe that you observe appears to slow down, and would come to a dead stop if you where travelling at the speed of light. This has the implication that anything that is travelling at the speed of light, such as a photon (a particle of light) is frozen in time. This is why it was a major issue for science to determine whether a tiny insignificant particle called a neutrino had any mass. Neutrinos are emitted during the nuclear fusion process which powers the Sun. However, only about 1/3 of the predicted number of solar neutrinos where detected on Earth. Now this either meant that the Sun was dying or those particles where changing so as to not be detected. If they had zero mass they would have to travel at the speed of light, making them frozen in time, and hence unable to change, and therefore the Sun is dying. Fortunately for us it turns out that they do have a very tiny mass, and so they can turn into something else (a different type of neutrino).
"My own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose." - J. B. S. Haldane
"And I, for one, find that a comforting thought." -Gandalf
My biggest problem with time dilation is the idea that every observer has their own clock so to say.
I had always assumed that the passing of time was constant and the same for everyone.
This does not seem to be the case though. And I'm having a hard time to accept and understand that.
That's pretty much THE key idea of Einsteinian relativity. It works because it has to, because the speed of light is a constant however the observer is moving.
Yeah, except when moving through glass. Then it's speed is roughly cut in half. Lightspeed is, like anything else, relative. Like time, it seems.
Different phenomina. When trying to explain something to someone with no background in a subject it isn't a good idea to introduce factors that do not influence the conclusion. You don't need relativity to explain the motion of light through a medium.
And given that most glass has a refractive index of around 1.5, it would be more accurate to say the speed is reduced by about 1/3 if you want to pick nits.
"However, a photon emitted from a star in Andromeda and heading out towards the Earth travels in a vacuum and, because it's a photon, travels at the speed of light. Because the photon is moving at the speed of light it has a 100% time dilation factor. To the photon time does not exist until it strikes the upper atmosphere of our planet and even then is only slowed down by a tiny fraction. According to a photon in free space, time, or for that matter distance, has no meaning whatsoever, and it gets from wherever it is to wherever it is going instantly!"
Mind = Blown
Today I learned future lengthy space journeys will be done by way of selfies.
Comments
Because it's not like they already had a trilogy of games focusing on humans in the ME universe.
The greatest hope is that the energy problem in warping space-time is solved. If you get a ship that can warp space before it to a factor of 10, effectively traveling 10 times the speed of light, it could reach Proxima Centauri in 40 hours and only 40 hours would have passed on Earth as the ship isn't actually traveling at the speed of light but warping space-time around itself.
The problem is that only forming the warp envelope around a ship to reach this factor of 10 would require energy equivalent of the entire mass of Jupiter being converted into energy in a fraction of a second. If you want to know what kind of energy this means, just use the mass of Jupiter in kilograms to the famous E=mc2 equation... Trust me it's a lot of energy...
There are scientists dedicated to finding a solution to the energy problem, such as the Tau Zero Foundation, created by a former NASA physicist, but, as far as I know, nobody has found a solution.
Other proposed solutions such as artificial wormholes meet both the energy problem and the stability problem. Opening a stable wormhole would require both dark matter and dark energy and we have no idea how to generate, capture or store them.
*other good documentry makers exist.
@mlnvese, started reading the link you posted. Great stuff!
Luckily for us, some even weirder apes realized the counter-intuitive was actually true and the thing which intuitively followed from our basic sense perception was, in fact, an illusion. We were the ground which was spinning, but feet firmly planted don't register that motion, and conspire with eyes to fuel the subsequent illusion.
A lot of stuff is like that, it turns out. Feeling oneself at the center of something often makes the things outside seem mappable to that backgrounded, ignored default...which is more often wrong than right. Time and space are no exception!
Is the time dilation per % of lightspeed an approximation or is it proven? It seems.. too perfect that it's exactly 10x to 100%. And what does 10x mean? In the text it seems there are time dilations higher than 10 times the normal earth speed of time.
Unrelative to the thread, but as an FYI - been listening to space ambient music for a couple of days now and been thinking alot about 'space'; the size, our little planet and what it would feel like to ride through the vast, empty space alone on some space ship.
Like all proper science, it starts with an observation. In this case, that when you measure the speed of light you get the same answer, irrespective of how you are moving when you do the experiment. This cannot be explained using the laws of motion calculated by Isaac Newton. If you want to know how the original measurement was made, look up the Michelson-Morley experiment.
Since speed is equal to distance divided by time, for the speed to remain constant, distance and/or time must change with the motion of the observer.
How we know it is correct is in it's use: if we used Newton's laws to calculate the position of satellites, GPS wouldn't work. With Einstein, it does. That doesn't mean it is absolute truth though. Science doesn't peddle "Truth". It works for all the observations we can make now, but there many be observations that we become able to make in the future that mean that the theory has to be modified. Newtonian mechanics still works perfectly well for pretty much any every-day life situation.
As for the limits of time dilation, as you approach the speed of light, the rest of the universe that you observe appears to slow down, and would come to a dead stop if you where travelling at the speed of light. This has the implication that anything that is travelling at the speed of light, such as a photon (a particle of light) is frozen in time. This is why it was a major issue for science to determine whether a tiny insignificant particle called a neutrino had any mass. Neutrinos are emitted during the nuclear fusion process which powers the Sun. However, only about 1/3 of the predicted number of solar neutrinos where detected on Earth. Now this either meant that the Sun was dying or those particles where changing so as to not be detected. If they had zero mass they would have to travel at the speed of light, making them frozen in time, and hence unable to change, and therefore the Sun is dying. Fortunately for us it turns out that they do have a very tiny mass, and so they can turn into something else (a different type of neutrino).
"My own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose."
- J. B. S. Haldane
"And I, for one, find that a comforting thought."
-Gandalf
And given that most glass has a refractive index of around 1.5, it would be more accurate to say the speed is reduced by about 1/3 if you want to pick nits.