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Useful info

cruise (September 25th, 2003, 1:35 pm)

First, has a nice description of the basics of forces, and some of the new thoughts on gravity and dark matter. I can already see a couple of story ideas in there...

Second, last weeks New Scientist feature article was on Time Travel, and helpfully lists the seven known ways of time-travel under General Relativity:

1) Godel's Universe

If the universe is spinning then light no longer travels in straight lines, and it's therefore possible to take shortcuts, travel fast than light, and on a long enough journey, arrive before you leave.

2) Van Stockum Space-Times

All these revolve (pun intended) around a super dense column or line rapidly spinning. With sufficient mass and rotation, the space-time distortion created enables an orbiting traveller to skip backwards in time. The more orbits, the further back.

3) Kerr black-hole

A spinning blackhole, this stretches the singularity at the centre into a ring, which can send you back in time if passed through in exactly the right way. It won't do you much good, however, since you'll still be in a black hole, just earlier than before. A five-dimensional variant, BMPV black hole, extends the time-loops outside the hole's boundaries with sufficient rotation, but see my notes at the end.

4) Gott's Time Machine

Two long, super-dense stings passing each other at high speed allow you to travel backwards in time if you loop around them as they pass each other.

5) Space-time foam

Below the planck length (10^-35 metres), space-time is a mess. Travelling backwards and forwards in this time is like "bobbing up down with the waves on a stormy sea." Unfortuantely, it's also way belong the size of any particles, so this might be pretty hard to use...

6) Morris-Thorne Wormholes

Probably the most well known method these days. Take a wormhole, make one end travel at a high velocity, and because of relativy's time dilation, one end will be "behind time" to the other. Send something through the advanced end, and it would come out the other end before you put it in.

7) Alcubierre Warp

Fold space, create a tunnel between two points. Faster-than-light travel, with the nice added bonus of acting as a time machine. Presumably such a space-folding is different from a wormhole, though why isn't explained.

Googling should turn up any info you want, since I coped the names direct from the article.

The reason all this was mentioned is that researchers have discovered that super-string theory prevents two of these methods (Godel Universe and the BMPV black holes) from occuring. If you want more detail, let me know...both are pretty complicated, so I won't go into them here...

Still five more valid techniques though... :P

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BlacklightResponsive (September 25th, 2003, 7:57 pm)

So if I write something about this, will you be happy? I very much do enjoy to make people happy.

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BlacklightResponsive (September 25th, 2003, 8:01 pm)

So, one day, one super dense string is floating by at a liezurely clip of near light speed, when another super dense string passes him. During this pass a man started spinning around the two of them as they sped past one another, stimulating their time differentials. He stared out slow, barely making a revolution every pinto-second, but his speed quickly increased and topped off at a near 300 revolutions per pinto-second before he was through. The one super dense string then remarked to the other, "Wow, these time slip orgasms are great, it's like I'm constantly cumming, but at the same time I can't help but get the feeling that I premature ejaculated."

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kromekoran (September 26th, 2003, 8:34 am)

wait, I thought you could only go one way through wormholes...

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kromekoran (September 26th, 2003, 8:36 am)

or did I read that wrong?


BlacklightResponsive (September 29th, 2003, 11:56 pm)

Its hard to say whether or not you can go back through them, but Michael Crighton already used this idea in Timeline.


BlacklightResponsive (September 29th, 2003, 11:56 pm)

Quantum foam makes me roam.

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