What do you think the real confusion is in the twin "paradox" and special theory of relativity?

Question

It is easy enough to go through and prove there is no paradox in relativity.

Makes sense - it is a mathematical theory derived from established mathematics. People still don't buy it though.

I think the real problem is the conclusion we try to draw from "thought experiments." Creating fictitious situations has a way of masking reality.

Case in point, if you REALLY put a person in a space ship and flew him at half-light speed to a distant star and back, would he really come back that much younger than his earthbound twin?

I'm guessing no, because the simple twin-paradox problem neglects way too many other factors that would actually come into play.

Answer 1

The confusion is simply the result of the contridiction of our common sense based on our earthly observations vs. the reality of how the universe actually works.

The same confusion existed when it was proposed that the earth was not flat - or the stationary center of the universe.

The twin paradox is absolutely real.
Time slows with accelleration, greater gravtational fields and speeds approaching that of light. All actual observations and experiments have confirmed this phenomenon to be exactly as predicted by Einstein's formulas and equations.

If a real person were to be accellerated into space, fly at half light speed for a while and accellerate back, he would find that the earth and the people on it have aged more than he has.

When time slows due to this phenomenon, all processes slow - from biological right down to the molecular levels.

Before you consider that the person sent from earth has found the fountain of youth - consider this:
If two people can perform a task in one hour and they start at identical times on earth - and then one of them is accellerated into space. When the one on earth has finished his task - the one in the spaceship would still be working on it - his hour has been stretched out.

If the one accellerated sends a message back to his buddy on earth, the one on earth would have to tape the message and speed up the playback to make it understandable.
In other words - the perceived time for both is the same - it litterally takes two earth years for the one in the spaceship to perform the same tasks as the one on earth has finished in a year (relative to earth time).

The twin paradox occurs when the two different references are brought back together and compared.

Answer 2

"...if you REALLY put a person in a space ship and flew him at half-light speed to a distant star and back, would he really come back that much younger than his earthbound twin?..."

Einstein's theory that leads to time dilation--which is what's going on with the so-called twins' paradox---has been shown over and over again to be an actual phenomenon by careful and very precise experiments. The most well-known deals with two atomic clocks that have been exactly synchronized. One clock is flown around for a prolonged period aboard a high-speed jet then brought back. The once-synchronized clocks no longer show the same time.

Answer 3

The twin paradox on exists in special relativity. If you consider general relativity it goes away. Here is why:
In order for the equations of special relativity to apply you can not have acceleration. But in the twin paradox you have accelerate one twin to a velocity close to c, then he decelerates to a stop reverses direction and accelerates to high velocity again. When you consider all these accelerations you can distinguish which twin will age slower, and the paradox disappears.

Answer 4

There is no paradox. General Relativity put the supposed paradox to rest.
You have it wrong, however, because the travelling twin would in fact be younger. There is nothing wrong with the thought experiments of Einstein, I think you just don't quite understand them.

Answer 5

Ahh...as with all physics, there is both positive and negative values. Would not the return trip yeild a recinsion of any effect acheived by the away journey?

One must first fully grasp the concept of relativity. As it relates to lightspeed, the concept is that TIME itself flows as defined by change in space. no movement, no time. Movement relative to what?

Could you not say that when one twin leaves earth at half lightspeed, he could think himself as standing still and his brother as moving? Could not BOTH brothers see the other's time as being faster?

What happens if they were triplets and the third brother, halfway to that star, launches away from the second brother's spaceship at 3/4 lightspeed relative to the spaceship? Does the first brother witness 1.25 lightspeed from his vantage?

NO! Nothing travels faster than light. Since their space is traversed at different near lightspeed velocities, IT IS THE TIME THAT CHANGES AS THEY VIEW THE TIME OF OTHERS.

BUT, THAT IS RELATIVE!!

The triplets are assumed to return to the same "space" and relative velocity. They will return to a place where they measure time the same.

Let us say that a year has gone by. Is it the same year for all three? Each will say:

"Only a year has gone by, but your time was faster than mine."

All three say that same thing.

SAME YEAR, SAME AGE, SAME TIME (for now) - NO PARADOX.

The near lightspeed velocity alters the time, but only RELATIVE to how they see time flowing upon another, and not upon themselves.

YOU might right now be travelling at close to lightspeed relative to another place in space. Without a change in space, there can be no time, Since lightspeed is the absolute, then time itself becomes a deviation of that...relatively speaking.

Answer 6

No paradox: http://en.wikipedia.org/wiki/Twin_paradox

The two frames are NOT symmetrical, therefore, you cannot apply reverse Lorentz contraction to the stationary twin.

Time dilation exists, all GPS satellites have demonstrated a time error due to relativistic effects:
http://en.wikipedia.org/wiki/Global_Positioning_System#Relativity