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Indicative
03-27-2016, 02:56 AM
Every now and again, we all indulge in dreams of traveling in time. Wouldn't it be wonderful to return to that specific point in the past to change a bad decision or relive an experience -- those halcyon days of childhood. The mystery of time travel is full of excitement and wonder.

By using mathematics you learned at school and with a little help from Einstein's time dilation formula you can show that time will slow for someone who is moving. Einstein's theory says that if you want to slow time down -- essentially, to time travel -- you need to move fast, very fast! Imagine setting off on a mission from Earth in the year 2000, for example. You are scheduled to be away until 2032, but will be traveling at 95% the speed of light (around 285,000 km a second). The amazing thing is that, on your return, your watch would tell you that it is 2010, despite it being 2032 on Earth, and you'd be 22 years younger than anyone you left behind. That's time dilation and it works at slower speeds, too, albeit to a much less profound degree.

But there's a catch -- 285,000 km a second is very, very fast. The fastest land vehicle cannot even get to 1 km a second and even a spaceship when escaping Earth's atmosphere is traveling at a relatively pitiful 10 km a second. Even if we could reach these speeds, it is questionable whether we could survive the stress on our bodies. So time travel into the future is possible, but a bit too difficult -- for now.

So, can you build a Time Machine? Yes, you can.

First, you need a lot of money to buy a large cylinder, perhaps a 100km long. The cylinder also needs to be at least the mass of the sun, but very densely packed together. You then need to start it rotating, faster and faster, until it's rotating so fast that it starts to disturb the fabric of both space and time -- and you would be able to detect a wash of gravity waves coming from this structure.

I also need to add a health warning, as coming close to such a dense structure would cause issues. The mass of the Earth pulls us down to its surface, but getting too close to an object this massive would be hugely dangerous -- it would drag you towards it and squash you flat.

If you can get round this squashing problem, however, approach the rotating cylinder and start following its spin -- as you get closer, strange things will start to happen. Your path, which normally inextricably moves you forward in time, changes, since moving around the cylinder in the direction of rotation will shift you back in time. The machine makes the direction of time collapse into the past, so the longer you follow the machine's spin, the further back in time you will go. To reset the movement to normal, simply move away from the cylinder, go back to Earth and you will be returned to the present -- albeit a present in the past.

But be careful what you do there. Fiddle around with the past too much and -- like Marty McFly in Back To The Future -- you may just break up your parent's first date or even ruin your chances of being born. Time can be funny like that.

|ThyLuigi|
03-27-2016, 04:23 AM
That's known as Einstein's Theory Relativity, in case anyone was wondering, which has faithfully predicted most of the things it states. Recently, gravitational waves were detected that shook space-time coming from two black holes colliding a few billion years ago. :3

Anyway, that is a sort of loose definition of time travel, don't you think? You aren't really going forward or backwards through time, time is just racing past you as you race through space.