Time Travel Machines
Created | Updated Jan 28, 2002
We can walk forwards or backwards, slide left or right and go up and down stairs, but we can only go forwards in time. Time travel has featured in many stories and movies. From H.G. Wells' The Time Machine to more modern onelike Doctor Who, Back to the Future and The Terminator. Physicist have been designing pratical time machines.
The Tippler Time Travel Machine was invented designed by Frank Tippler from the University of Texas. His machine is built from neutron stars. Neutron stars are a star that weighs about as much as our sun, but is only 10 or so kilometres across, not 1.5 million. It's extremely dense and s it has a very strong gravitational field. This is so intense that it seems to warp the very time-space continuum.
How to make a Tippler Time Machine:
Get a bunch of neutron stars and fashion them into a cylinder about 100 kilometres long and with a 10 kilometre radius. Then spin the cylinder about 2000 times per second. The surface would be moving at half the speed of light by now. According to Tippler's theory it should be draggin the space-time fabric with it, with enough force to mix up space and time. Now fly a your spaceship in a specific orbit around the giant cylinder. This should, in theory, take you back in time, but only till when the machine first started spinning. As you can imagine this requires some practically improbable engineering, but there are no theoretical reasons why it won't work.
Einstein's famous theory of Twin Paradox is another method for time travel. Einstein demonstrated that if you travel very fast, time will slow down for you.
How to use the Twin Paradox theory:
Get a pair of identical twins. One twin stays on the Earth, while the other is sent away on a spaceship travelling very fast, close to the speed of light. The travelling twin returns after one year as measured by her onboard clock, only to find that everything on Earth, including her twin, has aged half a century or so. The effect is a form of time travel.
Another theory requires the use of wormholes. A wormhole, if it actually exists, is a rip in the space-time fabric, sort of like a tunnel. Theoretically it joins two points of the universe, and can be used for instant travel, without actually travelling the full distance. So once youe enter one mouth of a wormhole, you instantly pop out of the other, even if it is a million light years away. One problem is that the wormhole would close up as soon as any object tires to enter. They managed to find a way around this without defying the laws of physics.
How to make a time travel machine using wormholes:
First, put the two mouths of the wormhole close together so they share the same time. Next, grab one end of the tunnel and accelerate rapidly to very close to the speed of light, taking away for about two hours. Bring the mouth back again. The wormhole will stretch itself in length as you take it away and will shrink back when you bring it back. Now, because the well-travelled mouth was moving very fast, time slowed down for it, thus using the Twin Paradox, in fact the other mouth is now 2 hours older than it. So if you drive your spaceship into the stationary mouth, you'll instanly pop out 2 hours earlier through the other.
There are however certain problems associated with time travel. One is the famous Grandfather paradox. What if, when we had invented time machines, you went back in time, and accidently landed on your grandfather, who as of yet had not had children. You would simply pop out of existence because you could not have been born. Then, you could not have killed Grandpa, and so he survives and you are eventually born and go back in time and land on him again, so you instantly pop out of existence..... A can be seen you would stuck in loophole.
Another physicist found a way around this, the old Parallel Universe theory. You start of in a universe where you exist then go back in time and kill you Grandfather in a universe where he never had children in the first place. And as such this doesn't create a paradox because it occurs in a seperate dimension.
People suggest that time travel could not possibly exist as we are not surrounded by people from the future. Physicists argue that the time travel machines may only be able to go back to when they were first made.
Another theory against time travel was the Chronology Protection Conjecture. At the time, it had many people convinced that time travel was impossible. It is now disregarded due to its ignoring of the gravitational effects of quantum fields.
It is well known that perpetual motion machines are impossible, but there are no laws of physics which rule out time travel machines.
The Tippler Time Travel Machine was invented designed by Frank Tippler from the University of Texas. His machine is built from neutron stars. Neutron stars are a star that weighs about as much as our sun, but is only 10 or so kilometres across, not 1.5 million. It's extremely dense and s it has a very strong gravitational field. This is so intense that it seems to warp the very time-space continuum.
How to make a Tippler Time Machine:
Get a bunch of neutron stars and fashion them into a cylinder about 100 kilometres long and with a 10 kilometre radius. Then spin the cylinder about 2000 times per second. The surface would be moving at half the speed of light by now. According to Tippler's theory it should be draggin the space-time fabric with it, with enough force to mix up space and time. Now fly a your spaceship in a specific orbit around the giant cylinder. This should, in theory, take you back in time, but only till when the machine first started spinning. As you can imagine this requires some practically improbable engineering, but there are no theoretical reasons why it won't work.
Einstein's famous theory of Twin Paradox is another method for time travel. Einstein demonstrated that if you travel very fast, time will slow down for you.
How to use the Twin Paradox theory:
Get a pair of identical twins. One twin stays on the Earth, while the other is sent away on a spaceship travelling very fast, close to the speed of light. The travelling twin returns after one year as measured by her onboard clock, only to find that everything on Earth, including her twin, has aged half a century or so. The effect is a form of time travel.
Another theory requires the use of wormholes. A wormhole, if it actually exists, is a rip in the space-time fabric, sort of like a tunnel. Theoretically it joins two points of the universe, and can be used for instant travel, without actually travelling the full distance. So once youe enter one mouth of a wormhole, you instantly pop out of the other, even if it is a million light years away. One problem is that the wormhole would close up as soon as any object tires to enter. They managed to find a way around this without defying the laws of physics.
How to make a time travel machine using wormholes:
First, put the two mouths of the wormhole close together so they share the same time. Next, grab one end of the tunnel and accelerate rapidly to very close to the speed of light, taking away for about two hours. Bring the mouth back again. The wormhole will stretch itself in length as you take it away and will shrink back when you bring it back. Now, because the well-travelled mouth was moving very fast, time slowed down for it, thus using the Twin Paradox, in fact the other mouth is now 2 hours older than it. So if you drive your spaceship into the stationary mouth, you'll instanly pop out 2 hours earlier through the other.
There are however certain problems associated with time travel. One is the famous Grandfather paradox. What if, when we had invented time machines, you went back in time, and accidently landed on your grandfather, who as of yet had not had children. You would simply pop out of existence because you could not have been born. Then, you could not have killed Grandpa, and so he survives and you are eventually born and go back in time and land on him again, so you instantly pop out of existence..... A can be seen you would stuck in loophole.
Another physicist found a way around this, the old Parallel Universe theory. You start of in a universe where you exist then go back in time and kill you Grandfather in a universe where he never had children in the first place. And as such this doesn't create a paradox because it occurs in a seperate dimension.
People suggest that time travel could not possibly exist as we are not surrounded by people from the future. Physicists argue that the time travel machines may only be able to go back to when they were first made.
Another theory against time travel was the Chronology Protection Conjecture. At the time, it had many people convinced that time travel was impossible. It is now disregarded due to its ignoring of the gravitational effects of quantum fields.
It is well known that perpetual motion machines are impossible, but there are no laws of physics which rule out time travel machines.
