Question about twin paradox - Page 3

On July 22 2011 03:07 XxDefexX wrote:
Cool!! Thanks a lot for the explanation. Say we were to make a glass with very small holes in it. Given the right proportions, the water would actually stay in the glass and thereby stay close to the other water molecules, instead of leaving the glass?

On July 22 2011 03:07 XxDefexX wrote:
Cool!! Thanks a lot for the explanation. Say we were to make a glass with very small holes in it. Given the right proportions, the water would actually stay in the glass and thereby stay close to the other water molecules, instead of leaving the glass?

On July 22 2011 03:13 JinDesu wrote:


I forget the name of the fabric, but there is a fabric that can hold water because of surface tension phenomenon. If I can remember the name of the fabric, I'll find links to it.

On July 22 2011 03:15 XxDefexX wrote:
I see, it would be nice though. Say I ragequit a 1v1 game and accidently hit my glass of coke, a little hole occurs but it doesn't spill on my computer cause of surface tension, so I can keep 1v1-ing :D. Please let me know, if you find the link

On July 22 2011 01:07 skunk_works wrote:
how does traveling at the speed of light keep you from getting old?

On July 22 2011 05:06 Sabin010 wrote:
The real question is what if the twins kept in contact via morse code through entagled particles?

On July 22 2011 01:02 Nawyria wrote:
The Lorentz transformation in flat space-time is a continuous transformation, so the signal will not be discrete; however, the signal will be distorted due to the relativistic doppler-effect.
Name the twin that stays on earth twin A and the travelling one twin B; assume further that they communicate by way of a continuous stream of light that varies mildly in wavelength around 550 nanometres (yellow).

1B) As twin B moves away from the earth at high speed, the relativistic doppler-effect redshifts the light signal, the signals he receives are in the red or infrared. He will also receive the signals at a lower pace due to the fact the light signals have to catch up to him, and thus the intensity will be much lower and the transmitted message plays very slowly.
2B) Just after twin B reverses his direction of travel (which we will assume he does instantly), all the signals he has been travelling ahead of will catch up to him in a very short amount of time. Since twin B is now travelling towards earth, the signals will be blueshifted and the signals he receives are in the blue, ultraviolet or beyond. He will now receive the signals at a much much higher pace, so the intensity will be much higher and the transmitted message plays extremely fast.
3B) After this short burst has passed and twin B is travelling back towards the earth, we are in the inverse of situation 1B. The light signals are blueshifted (as in 2B), the intensity is higher (though not as high in 2B) and the message players faster (though not as fast as in 2B).

1A) After twin A says his farewell to twin B, he will receive messages at a very slow pace, with the same redshift, intensity and message speed as in 1B.
2A) As twin B nears earth, all the messages that he has sent since turning around will reach earth in a very short fashion, much like what happens in 2B, only the intensity will be even higher.

Edit: Assuming the distances are vast enough for twin A to die as twin B is travelling, it depends on the speed of twin B whether he receives words of twin A's death as he is travelling or soon after he turns around. The faster twin B travels, the less messages he will receive before turning around, thus increasing the chance he will hear of it after he turns around.

On July 22 2011 05:14 Reborn8u wrote:
Time is relative to the individual. The twin traveling would experience time in slow motion. So if you could talk via communication hypothetically, the twin traveling might take an hour to say one word, as it was observed by the twin here on earth. But to the twin in space time would feel normal, and when the twin on earth spoke it would probably sound like it was on fast forward.
Here is something else to wrap your mind around. It takes 8 minutes for light to travel from the sun to the earth. If you had 1 long chain or rope and it stretched from the earth to the sun. When you pulled one end it would take 8 minutes for the other end to move.

On July 22 2011 05:06 Sabin010 wrote:
The real question is what if the twins kept in contact via morse code through entagled particles?

On July 22 2011 00:49 Jombozeus wrote:
Well, your signal would take a near-infinite amount of time to reach your twin if hes traveling at near the speed of light.

In other words, its probably just not going to reach him within his lifetime after 2 days if hes traveling at 99% speed of light. Just do the math.

On July 22 2011 01:58 Blazinghand wrote:
A similar, but somewhat different effect happens with "time dilation" where if I communicate, say, through a series of pulses, each pulse and the gap between each pulse becomes shorter and shorter as my reference frame moves faster and faster. This would make the establishment of some sort of communications standard very difficult, since anything using frequency would be out the window, or extremely hard to calculate.

On July 22 2011 01:07 skunk_works wrote:
how does traveling at the speed of light keep you from getting old?

On July 22 2011 05:38 Frigo wrote:


There are self clocking signals that would make this kind of communication possible, provided you have a means to intercept shifted frequencies properly.

I'm not sure about the latter tho, signal to noise ratio of time dilated signals might be pretty bad to make any kind of receiver impossible. You need to have a receiver capable of receiving very high frequencies, that's for sure. It would be certainly interesting to look into this matter.

On July 22 2011 05:43 Blazinghand wrote:
I never said that establishing a communications standard would be impossible, just that it was "very difficult". Assuming, of course, that you can move at .99c, instead of firing lights you could just launch projectiles at .99c towards home, and which projectile you launch could be code for the message.