Time Dilation - Albert Einstein and the Theory of Relativity

Two spaceships are traveling together through the galaxy at close to the speed of light. Mounted on one ship is a laser that can fire pulses of light, and on the other, a mirror. The pilot of the first ship fires a pulse at the mirror, and watches as it is reflected back. A clock on board measures how long the round trip takes.

But now suppose that he does this as the ships are passing an observer on a nearby asteroid. According to relativity theory, this observer sees the pulse moving through space at exactly the same speed that the pilot does -- namely, the speed of light. But he also sees the pulse traveling a longer distance, because from his perspective, he must add the forward motion of the ships to the motion of the pulse between them. So he measures a longer time interval for the round trip than the pilot does, because he is watching the pulse go farther without going any faster. This effect is called time dilation: if one observer is moving with respect to another, each perceives that the other's time is flowing more slowly.

National Science Foundation

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[ven0IVI]

perfect example... never really understood it til now

[jsrpictures]

λ - Lambda!

[tubertomp]

the velocities are the same because time is slowed down from the frame of the travelers but not so for the observer, v = d / t

keep in mind this is an extreme example, and although time dilation is the most commonly spoken about dilation mass also increases as one approaches the speed of light. the regression for the amount of force to overcome intertia to increase speed is such that one can never reach 1c. also if you tried to enter a worm hole in time via a black hole time would slow down.

[ImageRaiter]

@monstamunch90

The one where the boy travels at the speed of light and one stays on earth involves Acceleration and Deceleration, and is much harder to explain. Look up for the Twin Paradox.

[ImageRaiter]

@matt876mma

Time dilation phenomenon is very real and has been scientifically proven over and over again.

[plix3r]

@baroknight I was asking myself the same question.

[popshuvitskater]

@baroknight no because the light is moving with the rockets

[baroknight]

Wouldn't the lazer miss the mirror as the rocket is moving near the speed of light?

[trfinck]

@monstamunch90 of course it validates it as Sagan was validating Einstein

[trfinck]

@matt876mma time dilation isn't a "maybe", this has been proven in a lab. In fact, a perfect example is GPS satellites. They need to compensate for time differences as it travels around the planet. As Richard Feynman once said, "people can believe these absurd stories of how the universe was created, but the reality is that its much weirder than that."

[matt876mma]

I dont believe this time dilation theory. It's way too bruce willis science fictiony for me. If i travelled the speed of light for a few hours. Thats just means i'm fast dont mean i've travelled in the future or i will age more slowly, and things on the outside will age must faster. I need more solid proof before i believe in this.

[monstamunch90]

...so how does this validate Carl Sagan's video explanation of time dilation, in which a boy travels at almost a speed of light for a few minutes, only to return to his friends, finding out they have aged decades. So this is where I'm confused... It seems to say it is only the observers perception that makes it appear to be moving slower, whereas the theory also explains time DOES slow down. Can somebody please clear this up for me??