And that won't confuse any layman at all, "no the light doesn't really slow down it's just their average speed is reduced"
Speed of light and its affects
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And that won't confuse any layman at all, "no the light doesn't really slow down it's just their average speed is reduced"
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And that won't confuse any layman at all, "no the light doesn't really slow down it's just their average speed is reduced"
It's important to remember that time is relative, in otherwords there is no 'universal time', everyone has their own personal time. You can measure time however you like, many different ways of varying accuracy and none will be affected by travelling at speed as viewed by an observer in the same frame of reference as the clock.
The one universal constant that we have found so far is light speed (c). No matter how fast you are going or with frame of reference you or the light exists in everyone always sees the light travelling at exactly the same speed. i.e. you're flying in a space ship travelling at 0.9c, you turn on your headlights and you see the light moving at speed c, a guy standing still relative to the space ship sees this and also notes that the light is travelling at c. Conventional thinking would lead you to assume the velocities would add and the light would travel at 1.9c but this is not the case.
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Light bulb just clicked on. So the speed of photon never actually drops below maximum speed. Otherwise photons would have mass in mediums. Cheers.
Yes that's correct but technically you've described it backwards. Something with 0 rest mass can only exist if travelling at c, since light has no rest mass it follows that it must always travel at c.
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I was gonna ask if light had a constant speed but thought it was a stupid q
Technically it does but it will appear to slow in a medium since it's getting absorbed and re-emitted all the time so it's quite common for people to say light slows down in a medium since it's a simplification of what is really happening.
The instantaneous velocity of light is always c but the average velocity can appear to be less then c.
The instantaneous velocity of light is always c but the average velocity can appear to be less then c.
What if I had a *really* long stick, and poked someone with it who was millions of miles away and at the same time I switched on a super bright laser? In the same way that with electrons down a wire, they move very slowly, but the electromagnetic waves are almost instantaneous. If you had a light enough stick that you could move it reasonably quickly, nothing has to go faster than the speed of light, but you would still have communicated faster than it. Unless there's a reason this wouldn't work
This wouldn't work.
Yak.h'cir, I may have missed this further back in the topic, but to what level have you studied this sort of stuff. Because you seem to give the impression of knowing a lot more than some of the lecturers that I have met, and I'm not being harsh to the lecturers, because they know a lot.
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no because the twins have a different reference of time, the rocket twin, has been travelling for 10 years (from the POV of the earth twin), but to the rocket twin him its only been a few days..
After the rocket twin returns to earth and is reunited, the earth twin is 10 years older
When calculated using the original time reference they are obviously the same age but if each twin had 2 perfect clocks counting each second, the rocket twin would be 10 years younger..
I dont see any paradox in the twin paradox nonsense
i believe i see the problem now, assuming the rocket twin did the 5 year (from earths perspective) journey in like 1 day ... on the way back the same will repeat.
Do you think that because he is travelling backwards he will now reverse time for the observer? while keeping himself in a state of normal time?
i think your thinking about time flowing in 1 direction, and travelling back would cancell it out, and they would then be exactly the same age?
I have a masters in Astrophysics from Bristol. If the lecturers you're referring to are Physics lecturers they should still know a fair bit more then me though.
EDIT:
This was a few years ago now and I really don't consider myself an expert, but I do take the time to confirm what I'm saying if it's something I'm not 100% on.
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I think describing things in words can sometimes help with understanding, Yak.h'cir will have had time to think about what he was going to write and adjust it afterwards to ensure clarity. Something you can't really do if you are thinking and explaining in real time
EDIT\\ likewise you have the opportunity to reread what he has written and absorb the information before moving on, again something you can't always do in real time
The paradox comes in because you can consider either twin to be the one that is moving, i.e. once the spaceship has reached its cruising speed and stopped accelerating any experiments/observations performed would not be able to confirm whether it is the ship that is moving relative to the Earth or the Earth that moves relative to the ship. However the paradox is resolved when you consider that only one twin is changing inertial frames (since he turns around to come back) so the two are no longer symmetrical and this is what accounts for the differing ages.
Yeah it's easy to trip yourself up when talking about relativity, it's just so different from what we experience in everyday life! It's definitely something that you need to think carefully about before putting it into words but I find that the process of doing this improves your own understanding greatly.
Can a mod change it?
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Even if the twin doesnt turn around to come back, he would still be X amount younger..
I still dont get what exactly the paradox is suppose to be?
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What he was saying is that if twin A didn't turn around and come back, there would be no way to tell which one of them is moving. Is twin A moving away from the earth at 0.98c, or is the earth (carrying twin B) moving away from twin A at 0.98c? So there is no way to determine their relative ages. There may also be the slight problem of the earth not being an inertial frame of reference too.
Only when he slows down and rejoins the same inertial frame as his twin. Remember there isn't a universal time frame that exists between inertial frames.
It's a paradox because if you compare the ages during the journey you could just reverse the frame of reference and consider the twin on the ship is stationary whilst the twin on Earth is the one moving at 0.9c for example. The result appears to be reversed and you have the the older twin in on the ship and the younger back on Earth, hence the paradox. It's only when you consider the changing inertial frames that the paradox is resolved.
It's a paradox because if you compare the ages during the journey you could just reverse the frame of reference and consider the twin on the ship is stationary whilst the twin on Earth is the one moving at 0.9c for example. The result appears to be reversed and you have the the older twin in on the ship and the younger back on Earth, hence the paradox. It's only when you consider the changing inertial frames that the paradox is resolved.