please explain?about relativity?

Question

Twin Paradox.
One twin stays on earth. The other goes off into space at the speed of light. In earth time, he's gone for 20 years. When he returns, his brother has aged 20 years, but he hasn't aged at all

Answer 1

Yes, check out the birthday paradox on wikepedia. In essence,
this paradox demonstrates that mathematical truth contradicts naive intuition. I have included this paradox to demonstrate the nature of paradox. In understanding this paradox, you may have a better comprehension of the twin paradox that Einstein also solved mathematically. In doing so, he correctly contradicted the naive intuition of everyone.

The problem: If 23 people are randomly selected it is about a 50- 50 probability that at least 2 will have the same birthday. Most people when confronted with this problem will intuitively estimate that selecting only 23 people will be considerably less than a 50-50 chance of having at least 2 people with the same birthday.
They will also estimate that to get to a 50/50 probability it will have to be considerably more than 23.
At wikepedia they give several different mathematical approaches to solve this problem. The best and simplest is;

A simple exponentiation
P(n)= 1-(364/365) ^(nC2)=
1-(364/365)^(23C2)=
1- (.99726) ^ (253)=
1- (.499488)=
.500511872

(nC2) is also expressed as n Choose 2...This is a factorial.
Therefore (23Choose 2) gives you 253 possible combinations.
(23x22/2x1)=253 This will be the exponent for (364/365).

With 60 people randomly chosen, this exceeds 99% chance of getting at least 2 with the same birthday.
P(n) =1- (364/365)^(60C2)=
1-(.997260274)^(1770)=
1-.00778178=.99221822

In essence, some Paradoxes can be proven false, as this one has been demonstrated. Some of our false truths throughout history have been based on naive intuition and only resolved with counter intuitive approaches. I hope this helps! GL



Below is an answer I submitted to the question "Is time travel possible"? In addition to this, Time, Size, and Mass will all seem normal for those in their own reference frame. These entities would seem peculiar, for example, if earthlings could somehow see (see in another reference frame outside their own) the people traveling close to the speed of light. The Earthlings would see the travelers shrink, become more massive, and notice that their clocks were running significantly slower. The following is a a brief description of time , the 4th dimension. I hope this helps.

Yes, one aspect of time travel is theoretically possible. That is to say, according to Einstein's Special theory of relativity it is possible to travel into the future. How far in the future in a given time span depends how close to the speed of light you accelerate. Traveling at 80% of the speed of light according to Einstein's formula y=1/ Sqrt 1-v^2/c^2 ,(v=velocity, c= speed of light) the clocks on Earth will advance 1.667 times faster than the one traveling in space. Therefore, after a twenty year journey by the space travelers, (20 yrs time has elapsed by the travelers account) upon their return, there will have passed on earth 33.4 years.
At 98% of the speed of light, 20 years of travel at this speed, upon return, 100.4 years will have passed on earth.
This is the equivalent to traveling into the future, which is a form of time travel. Therefore time travel is theoretically possible. In fact, check out this site as the guy proclaims that we will be able to approach speed of light travel within 100 yrs.
http://www.physorg.com/news10789.html......
Traveling back in time is debatable, as you would have to be able to exceed the speed of light to do that.
Plug in the numbers to this formula. speed of light c= 186,000 miles per second. For velocity, just multiply this number from .01 to .9999. Then just follow mathematical operations.

Answer 2

as you approach the speed of light it is thought that time will stand still for you, so time wont advance

there have actually been test conducted on this using radio active decay as a means of telling time

Say you know the decay of carbon 14 is X/years then, you can tace a small amount of carbon 14 and accelerate it to nearly the speed of light using a particle accelerator, come back in a couple of years and measure the amount of decay the sample has undergone

Answer 3

One time Bill Nye explained this pretty well. I still didn't understand it though.