Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: dianella94 on 22/06/2014 09:34:40
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Can someone please put my husband out of his misery? He is driving me mad with his theories!
Time slows down as you go faster and approach the speed of light. If you get to the speed of light, time actually stops. Or at least as we understand it.
Now light travels at 3 x 108 m/s.
My husband has done a "back of the envelope" calculation. According to him: the earth spins at 0.5km/sec, the earth orbits the sun at 33 km/s. Our solar system orbits around the Milky Way at 250km/s. Our Milky Way moves in the local group of galaxies at 300km/s. So he has added up the numbers and he has surmised that if everything adds up, in other words, all the rotations sum up, the total speed of travel would be 1 125 000km/sec. Which is faster than the speed of light.
So, his questions are: are his calculations correct? If so, should time have stopped, at least when/if all rotations line up? We should be able to look out and see other galaxies speed up their time, is this possible? And finally, he has heard that it takes an infinite amount of energy to travel at the speed of light, so it should be impossible?
Please help. Its a Sunday night and I really don't want to be talking about this stuff!!!
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Can someone please put my husband out of his misery? He is driving me mad with his theories!
Sure.
Time slows down as you go faster and approach the speed of light. If you get to the speed of light, time actually stops. Or at least as we understand it.
Not really. Nothing can move at the speed of light so a clock can’t move that speed nor can any instrument. Therefore you can’t measure anything stopping making it meaningless to say such a thing.
My husband has done a "back of the envelope" calculation. According to him: the earth spins at 0.5km/sec, the earth orbits the sun at 33 km/s. Our solar system orbits around the Milky Way at 250km/s. Our Milky Way moves in the local group of galaxies at 300km/s. So he has added up the numbers and he has surmised that if everything adds up, in other words, all the rotations sum up, the total speed of travel would be 1 125 000km/sec. Which is faster than the speed of light.
That’s incorrect.
So, his questions are: are his calculations correct?
No. His calculations are incorrect. You can only calculate speeds like that, i.e. by simply adding them together, by using non-relativistic mechanics, i.e. you’re only using an approximation. When things start moving fast or there’s enough to sum up which makes the final sum close or past the speed of light then you can’t use that approximation, use relativity. To see how to do that see Eq. (9) in
] http://home.comcast.net/~peter.m.brown/sr/velocity_trans.htm
In any case there is no absolute frame of reference so we're at rest in our frame of reference and no object can move at or faster than light. Only light and anything having zero proper mass can move at the speed of light.
Besides. Bored Chemist checked your husbands work and found it to be way off. I never checked it.
Please help. Its a Sunday night and I really don't want to be talking about this stuff!!!
He can always send me a PM or an e-mail and I can answer any question about relativity that he has.
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OK, lets check the arithmetic.
"According to him: the earth spins at 0.5km/sec, the earth orbits the sun at 33 km/s. Our solar system orbits around the Milky Way at 250km/s. Our Milky Way moves in the local group of galaxies at 300km/s.
0.5km/sec
that's 500m/s
33 km/s
that's 33,000 m/s
250km/s
That's 250,000 m/s
300km/s
that's 300,000 m/s
Adding them together gives
583,500 m/s
The speed of light is
299,792,458 m / s
which is about 500 times faster.
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Hi Dianella94. Was your husband multiplying the figures rather than adding them? If so, I can empathise, I'm that sort of mathematician as well. :)
Hope the rest of your Sunday evening is maths free.
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Hello all, thank you for your replies. Yes, in his excitement he was multiplying the speeds not adding them. Yes, he is that sort of mathematician.