Hey physicists, I have a time travel question?

Question

I saw a program on tv the other day that was explaining how GPS works. Due to the effect that matter has on spacetime, time runs slower on earth than it does in space and in order for GPS to work correctly they have to account for that difference.

So what I was wondering is...

If an astronaut was orbiting space for quite a while and they then came back down to earth would they have effectively travelled in time? If so any idea how long they would have to orbit the earth for there to be a noticable difference? I realise that it would be no different that flying somewhere and having to adjust clocks for the time zone but unlike that, would it essentially be time travel?

Answer 1

Sort of. Time exsists as do different principles. One is preceived time(Ptime) this is what a clock measures. The other is biological time(Btime), most of the time it corresponds with preceived time. The difference is only noticable from outside the sphere of inflence. That is, you can't preceive the difference of time by just watching a clock at the GPS satelite, you would have to watch a clock on earth from the GPS. This is becuase gravity directly porportional to flow of time. Therefore, the more mass an object has, the more grvity it produces and the slower time flows. Also, time flows slow on the ocean floor than it does on top of a mountain. So yes, theoreticaly time travel is possible. If you want to skip ahead a few years go float near a black hole for a few secounds and a few thousand years will have past. And if you were 16 year old who wanted to see a raded R movie, go float in a pure vaccum for two years while only a few secounds or days have pasted here. This is travel through Btime, which cannot be reversed unlike the movies which is travel through Ptime. It is quite confusing, but fun to ponder.



Anyone is welcome to message me if they would like to discuss this or silimar things.

Answer 2

The answer to your question has already been answered by NASA years and years ago. Astronauts who had spent extended time periods in orbit around earth did lose an extremely minute fraction of one second during their entire experience.



No, this does not constitue a virtual time warp experience.

But right here on earth we are heading into the future with every day that passes. We just think of it as growing old.



We can not go backwards through time, only forwards. But scientists have observed sub-atomic particles travelling backwards through time when they smash atoms. Check that out, too. that is bound to be the nearest we shall personally experience travelling through time backwards, ourselves, unless we turn our bodies into atomic particles to get used in an atomic collider.



Explore the literature about matter falling into super massive black holes. That should be interesting but I am confdent you won't find your answer there, either.



Have fun.



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At the speed of light, there is no time. If your astronaut was able to speed along at exactly the speed of light, he could travel back home again and even if, say, he ws gone for 80 earth years of time as mesured on earth, the astronaut has not experienced any time and it would seem to him that he was only to get into his rocket just to get out again. He would not have aged but for a matter of a second while everybody else then alive here on earth has grown old and died.



The speed of light is the ultimate speed. Nothing can travel any faster than this. You look up the speed of light and read about it all by yourself. Also read what Einstein made of it.

One day perhaps we may build ships that travel close to the speed of light and the time dilation would be present. Maybe, if you did travel for 8o Earth years, the astronaaut may have saved one day in his life.



There is not enough energy in the entire cosmos to drive a single gram of matter along at the speed of light. So, the fun stories of Star Trek whereby the space ships speed up to several times the speed of light are just fun stories. It cannot happen. Maybe, one day, you can pursue this fascinating phenomenon and find what everybody else may have overlooked - the theoretical means to make it happen.



What would happen if you were able to succeed in going faster than the speed of light? You would go backwards through time. Theoretically, you could arrive back on earth in time to watch yourself take off.



Try and think of a way to illustrate that. Tip. You take off and are travelling at the speed of light. You decide to watch some television. You switch on your set . There is a still picture on the screen. You wait for it to move,but it never does. You try to radio back home but you cannot get through. Actually, you are speeding away so quickly your message gets left behind or stranded, the real "Lost in Space."



So you see what will happen and you speed up your ship. What does happen? The picture on the television screen starts running, but it is running bacwards. Cars go backwards down the street, People walk backwards.



Why would this be so? Think about it. tell yourself, not me.



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Answer 3

If they are orbiting the earth, aren't they still held by it's gravity and therefore unaffected by the effect that the earth's mass has on space/time?

Answer 4

i think the time difference between the gps satellites and earth is about 40 microseconds per day!