If time travel is possible, where are the tourists from the future? - Stephen hawking.
Most of us are familiar with at least a TV series that had the concept of time travel in it, famous series for this is “the flash” and “star trek”.
As you are reading this, you must be thinking that this moment is now, but no matter how much you loved your past and how much you desire your future, you are living in the present. The big conclusion is that the present keeps updating itself. You have now, the moment it’s gone, you can’t have it again, except you time travel of course. And this would be my focus today, how possible is time-travel?
First of all, lets understand time, most people believe that time is constant, but according to Einstein, he claims that time is just an illusion, it can vary for different observers depending on your speed through space. Many physicists supported him and concluded that time is just a “subjective illusion”.
What is time travel?
Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically using a hypothetical device known as a time machine, in the form of a vehicle or of a portal connecting distant points in space-time, either to an earlier time or to a later time, without the need for the time-traveling body to experience the intervening period in the usual sense.
Both backward and forward time travels has no certain origin, although it can be traced to the twentieth century.
Some theories, most notably special is general relativity, it suggests that suitable geometries of space-time or specific types of motion in space might allow time travel into the past and future if these geometries or motions were possible. Not all scientists believe that time travel is possible. Some even say that an attempt would be fatal to any human who chooses to undertake it.
Here are some theories that proved time-travel to be possible.
One of the biggest possibility of time travel is to travel faster than light (186,282 miles per second in a vacuum), although Einstein’s equations show that for an object to attain that speed, it must possess an infinite mass and length of zero. Which is physically impossible. So some scientists proposed alternative researches to prove that time-travel is very possible, let’s take a look at a few of those alternative time travel methods.
Wormholes:
NASA stated that there is a linked possibility of creating a “wormhole” between points in space time that would collapse very quickly and would only be suitable for very small particles. Also, scientists haven't actually observed these wormholes yet plus the technology needed to create a wormhole is far beyond any type of technology we have today.
Infinite cylinder
Astronomer Frank Tipler proposed a mechanism known as a Tipler Cylinder where one would take matter that is 10 times the sun's mass, then roll it into very long but very dense cylinder. After spinning this up a few billion revolutions per minute, a spaceship nearby — following a very precise spiral around this cylinder, could get itself on a "closed, time-like curve". There are limitations with this method, including the fact that the cylinder needs to be infinitely long for this to work.
Blackholes.
This involves moving a ship rapidly around a black hole, or to artificially create that condition with a huge, rotating structure. According to Stephen Hawking, the ship and its crew would be travelling round and round while experiencing only half of the time of people who are far away from the hole. But for this to work they must travel in the speed of light.
Physicist Amos Iron at the Technion-Israel Institute of Technology in Haifa, Israel, pointed out another limitation if one used a machine: it might fall apart before being able to rotate that quickly.
Comic strings.
Cosmic strings are narrow tubes of energy stretched across the entire length of the ever-expanding universe. These thin regions, left over from the early cosmos, are predicted to contain huge amounts of mass and therefore could warp the space-time around them. Cosmic strings are either infinite or they’re in loops, with no ends, scientists say. The approach of two such strings parallel to each other would bend space-time so vigorously and in such a particular configuration that might make time travel possible, in theory.
Reasons for some scientist’s disagreement.
- Some scientists disagree with the few options mentioned above and say time travel is impossible no matter the method you try.
- The faster-than-light one in particular drew derision from Charles Lu, that "simply mathematically, doesn't work,"
- Also, humans may not be able to withstand time travel at all. Traveling nearly the speed of light would only take a centrifuge, but that would be lethal, said Jeff Tollaksen.
- Using gravity would also be deadly. To experience time dilation, one could stand on a neutron star, but the forces a person would experience would rip you apart first.
So basically, theoretically all these principles work, but practically, it might never “work” really. Every day we are drawing closer to technologies that might eventually make time-travel possible, until then, TIME TRAVEL IS STILL NOT POSSIBLE.
Sources:
Wikipedia
Scientific American
Goodread
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Howstuffworks
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