FUTURE warns PAST —- Part 3

Einstein’s theory of relativity brought space and time together in a single, four-dimensional arrangement that he called spacetime. We know that we can travel forwards, backwards and sideways in space, so why not forwards and backwards in time? Mass warps spacetime. Four dimensions are difficult to imagine, so physicists usually suggest you think of spacetime as a rubber sheet stretched out flat. If there are no large masses around, the sheet stays flat, and so any object placed on it will move around in straight lines. But a large mass, such as the Sun, makes a dip in the sheet because it actually warps spacetime. Now any other object with smaller mass, like our Earth, moving about in spacetime rolls into the dip as it comes past the Sun. It appears ‘attracted’ to the large mass. This effect of warping spacetime is what gives rise to gravity. Light is bent around the curves of spacetimeThe Universe is full of heavy objects exerting gravitational effects and the net result is that spacetime is not flat at all but curved. Everything, including light, has to follow curved paths in spacetime. We know Einstein was right about this because astronomers can sometimes see distant stars that ought to be masked by nearer objects such as the Sun. Instead of travelling in straight lines and hence being blocked, the light from the stars bends round the obstruction. Microscopic structure. If you could look at spacetime with a magnifying glass so powerful that it reached down to the quantum scale, you would not see the smooth, continuous sheet of Einstein’s spacetime. Just as a foam rubber ball looks smooth from a distance but rough and ragged close up. In this picture of spacetime it is quite likely that tiny holes could open up, entrances to little tunnels between now and other times, or between here and other universes. Another option for future time travellers would be somehow to harness these tiny wormholes and expand them.

http://www.bbc.co.uk/science/space/exploration/timetravel/index.shtml

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http://www.ws5.com/spacetime/

http://www.spacetimetravel.org/

http://info.hartwick.edu/physics/spacetime.html

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https://gheorghe47.wordpress.com/2010/08/27/future-warns-past-part-2/

https://gheorghe47.wordpress.com/2010/08/22/future-warns-past/

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