Time is variable - how?
Discussion
It's probably my no.1 question that I still don't understand. I see a lot of stuff saying that time moves more slowly the further away you are or nearer to light speed you go but that doesn't make any sense to me.
If I sit here and send my mate into space at near enough light speed and then tell him to come back after 10 mins he's been 'flying' for 20 mins and yet somehow theory says he may have only been gone 5 minutes (as an example). What's going in with him then? Is he flying in slow motion or what?
Or is this something I'll never understand and it'll be 'it is, accept it.'?
If I sit here and send my mate into space at near enough light speed and then tell him to come back after 10 mins he's been 'flying' for 20 mins and yet somehow theory says he may have only been gone 5 minutes (as an example). What's going in with him then? Is he flying in slow motion or what?
Or is this something I'll never understand and it'll be 'it is, accept it.'?
You don't need to understand it to accept it.
It is weird to the casual observer, but it's real
Distance has nothing to do with it, but velocity and gravity do.
https://en.m.wikipedia.org/wiki/Time_dilation#:~:t...
Its A level physics complexity, but no more than this level.
As you get close to the speed of light, like really close, then time basically stops. But we can't do this yet anyhow, so don't worry
It is weird to the casual observer, but it's real
Distance has nothing to do with it, but velocity and gravity do.
https://en.m.wikipedia.org/wiki/Time_dilation#:~:t...
Its A level physics complexity, but no more than this level.
As you get close to the speed of light, like really close, then time basically stops. But we can't do this yet anyhow, so don't worry
have you asked chatgpt?
I've found it very useful for questions like that due to being able to use a couple of terms:
"dumb it down"
"imagine I'm 7 yrs old and try again"
"simpler please"
(none of the above is a joke btw... being able to back/forward with AI for topics like this is incredibly useful)
I've found it very useful for questions like that due to being able to use a couple of terms:
"dumb it down"
"imagine I'm 7 yrs old and try again"
"simpler please"
(none of the above is a joke btw... being able to back/forward with AI for topics like this is incredibly useful)
Frimley111R said:
Is he flying in slow motion or what?
Sort of, yes - because time itself is relative. i.e. to you, he's flying in slow motion, but to him, time is going at the normal speed and you are sped up / slowed down. i.e. Your perception of time depends on where you are, and how fast you are moving. If you are somewhere else, and moving at a (vastly) different speed, then the passage of time will be different for you because of this.
ikarl said:
have you asked chatgpt?
I've found it very useful for questions like that due to being able to use a couple of terms:
"dumb it down"
"imagine I'm 7 yrs old and try again"
"simpler please"
(none of the above is a joke btw... being able to back/forward with AI for topics like this is incredibly useful)
Lol, quite a good idea actually, didn't think of that.I've found it very useful for questions like that due to being able to use a couple of terms:
"dumb it down"
"imagine I'm 7 yrs old and try again"
"simpler please"
(none of the above is a joke btw... being able to back/forward with AI for topics like this is incredibly useful)
Gary29 said:
It's a head wrecker that I don't grasp either.
If you both synchronise your casio F91W's before your mate gets in the ship, would they not show the same time when he comes back?
Some light reading...If you both synchronise your casio F91W's before your mate gets in the ship, would they not show the same time when he comes back?
https://en.wikipedia.org/wiki/Hafele%E2%80%93Keati...
https://en.wikipedia.org/wiki/Error_analysis_for_t...
https://en.wikipedia.org/wiki/Twin_paradox
Also worth a watch:
https://en.wikipedia.org/wiki/Genius_by_Stephen_Ha... (this is on Disney Plus in the UK IIRC)
Gary29 said:
It's a head wrecker that I don't grasp either.
If you both synchronise your casio F91W's before your mate gets in the ship, would they not show the same time when he comes back?
No, they wouldn't. Anyone / anything moving relative to you experiences time dilation i.e. their watch will tick slower relative to you (it will look normal to them). In day-to-day life the dilation is far too small to notice, but using atomic clocks on something like the International Space Station it is noticeable because it's moving so quickly. There's a great little comic on xkcd ( https://what-if.xkcd.com/58/ ) showing how in many people's perception satellites are gently floating about weightlessly in space, when in fact they're hammering by overhead at about 35,000mph iirc. At those speeds, understanding time dilation is essential to modern life as where a huge amount of society now relies on GPS in one way shape or form, the GPS system has to account for the time dilation between you standing on earth looking at your location on your phone and the satellite that's transmitting the location data moving at 35,000mph relative to you. If you both synchronise your casio F91W's before your mate gets in the ship, would they not show the same time when he comes back?
There're loads of great vids on YouTube about it that are likely to be easier to follow than reading up on it. Here's one, for example: https://www.youtube.com/watch?v=1BCkSYQ0NRQ
If you don't have 10 mins here's a YouTube short that gives an explanation in 1 minute: https://www.youtube.com/shorts/qns3hiM4Fr0
Finally I would add that a lot of the physicists that come up with this stuff can't get their head round it either as it's so counter intuitive. Richard Feynman is considered to be the grandfather of quantum mechanics and is famously quoted as saying "I think I can safely say that nobody understands quantum mechanics".
Gary29 said:
It's a head wrecker that I don't grasp either.
If you both synchronise your casio F91W's before your mate gets in the ship, would they not show the same time when he comes back?
An attempt at explanation I saw...If you both synchronise your casio F91W's before your mate gets in the ship, would they not show the same time when he comes back?
Suppose your mate is going into orbit.
When your mate sets off travelling fast you have two frames of reference. To people on Earth the ship is going fast relative to them and therefore looks shorter in the direction of travel than it does to your mate. To your mate Earth is going fast and therefore the route looks shorter than it does to you. So when he gets back surprisingly quickly he is equally surprised how much time has passed on earth.
Time dilation due to gravity is a whole other issue, although to physicists it's probably fundamentally the same thing.
I watched a YouTube video about it not so long ago. Still confusing but one of the takeaways I got was the faster you travel at the speed of light the longer it takes for the forces between atoms to reach each other therefore the effect of time slows down relative to someone on earth for example. I could have completely misunderstood though.
Photons travel at the speed of light, because they have zero mass. Consider how long that photon has travelling since leaving that distant galaxy, maybe billions of years. How come it hasn't lost any of it's energy?
Because it's travelled at the speed of light, NO TIME has passed for the photon.
Because it's travelled at the speed of light, NO TIME has passed for the photon.
Time is a very local concept. As Earthlings, a day is the time it takes for the earth to rotate one cycle on its axis. An hour, 1/24th of that etc.
But once you leave the vicinity of this planet, what is a day? It's an entirely irrelevant unit that makes no sense anywhere else than here.
The most accurate way to measure time is to count the resonance frequency of atoms, usually cesium or rubidium. But this frequency whilst constant on earth, is affected by gravity, so again is only an Earth solution.
Once you start thinking universally, you need to start thinking about time as an entirely different concept.
But once you leave the vicinity of this planet, what is a day? It's an entirely irrelevant unit that makes no sense anywhere else than here.
The most accurate way to measure time is to count the resonance frequency of atoms, usually cesium or rubidium. But this frequency whilst constant on earth, is affected by gravity, so again is only an Earth solution.
Once you start thinking universally, you need to start thinking about time as an entirely different concept.
Orchid1 said:
I watched a YouTube video about it not so long ago. Still confusing but one of the takeaways I got was the faster you travel at the speed of light the longer it takes for the forces between atoms to reach each other therefore the effect of time slows down relative to someone on earth for example. I could have completely misunderstood though.
Yes - you haveTime dilation is real and has been measured.
However, any measuring done by an instrument travelling along with or even on board the object that is travelling at speed will also suffer the same time dilation effect - so, if you are on board such a high speed craft and you are watching the onboard clocks, everything will appear to you as if things are normal - as indeed they are, for you.
However, to an outside observer, THEY would see that everything happening on board the vessel was happening more slowly and that the clocks did appear to be running slowly.
Even things like atoms and the subatomic particles contained within them behave absolutely as normal as far as they are concerned - as long as they are being observed and measured by someone on board and travelling with them. But again, if you were able to measure their behaviour from a stationary position outside the vessel you would see that they were behaving as if everything had slowed down.
A number of experiments have been carried out over the years placing highly accurate atomic clocks on board aircraft and, even travelling at speeds of around 500 mph, distinct changes to the time keeping of the clocks on board the aircraft can be revealed.
When the clocks were taken from the aircraft and compared to a similar clock that had stayed on the ground, the clocks from the aircraft were found to have slowed down in exact agreement with Einstein's theory.
Fast and Spurious said:
Photons travel at the speed of light, because they have zero mass. Consider how long that photon has travelling since leaving that distant galaxy, maybe billions of years. How come it hasn't lost any of it's energy?
Because it's travelled at the speed of light, NO TIME has passed for the photon.
So from the photon's point of view it could equally be regarded as having started in an astronomers eye and travelled to the distant galaxy.Because it's travelled at the speed of light, NO TIME has passed for the photon.
Or we could say that photons don't actually travel anywhere but are just a relationship between a star and an astronomers eyeball. So the delay of billions of years until the astronomer notices their end of this quantum event is just down to the speed of reality.
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