Once Again, While browsing through Stephen Hawking's The Universe in a Nutshell
I stumbled upon one of the most intriguing questions in modern physics; The possibility of Time Travel!!
It is tricky to speculate openly about time travel. One risks either an outcry at the waste of public money being spent on something so ridiculous or a demand that the research be classified for military purposes. After all, how could we protect ourselves against someone with a time machine? They might change history and rule the world. Physicists disguise the fact by using technical terms that are code for time travel.
The basis of all modern discussions of time travel is Einstein's general theory of Relativity. The Einstein equations made space and time dynamic by describing how they were curved and distorted by the matter and energy in the universe. In general relativity someone's personal time as measured by their wrist-watch would always increase, just as it did in Newtonian Theory or the flat spacetime of special relativity. But there was now the possibility that spacetime could be warped so much that you could go off in a spaceship and come back before you set out.
One way this could happen is if there were wormholes, tubes of spacetime that connects different regions of space and time. The idea is that you steer your spaceship into one mouth of the wormhole and come out of the other mouth in a different place and at a different time.
Wormholes, If they exist, would be the solution to the speed limit problem in space : it would take tens of thousands of years to cross the galaxy in a spaceship that traveled at less than the speed of light, as relativity demands. But one might go through a wormhole to the other side of the galaxy and be back in time for dinner. However, one can show that if wormholes exist, you could also use them to get back before you set out. This is a variation of the Grandfather Paradox. Of course, this is a paradox only if you believe you have the free will to do what you like when you go back in time.
But whether the laws of physics allow spacetime to be so warped that a macroscopic body such as a spaceship can return to its own past?? There are many levels on which we can answer this question, but for the time being let me keep it as a secret. I'll disclose the answers in my next blog post!........Keep searching for the answers till then! Thank You!!
I stumbled upon one of the most intriguing questions in modern physics; The possibility of Time Travel!!It is tricky to speculate openly about time travel. One risks either an outcry at the waste of public money being spent on something so ridiculous or a demand that the research be classified for military purposes. After all, how could we protect ourselves against someone with a time machine? They might change history and rule the world. Physicists disguise the fact by using technical terms that are code for time travel.
The basis of all modern discussions of time travel is Einstein's general theory of Relativity. The Einstein equations made space and time dynamic by describing how they were curved and distorted by the matter and energy in the universe. In general relativity someone's personal time as measured by their wrist-watch would always increase, just as it did in Newtonian Theory or the flat spacetime of special relativity. But there was now the possibility that spacetime could be warped so much that you could go off in a spaceship and come back before you set out.
One way this could happen is if there were wormholes, tubes of spacetime that connects different regions of space and time. The idea is that you steer your spaceship into one mouth of the wormhole and come out of the other mouth in a different place and at a different time.
Wormholes, If they exist, would be the solution to the speed limit problem in space : it would take tens of thousands of years to cross the galaxy in a spaceship that traveled at less than the speed of light, as relativity demands. But one might go through a wormhole to the other side of the galaxy and be back in time for dinner. However, one can show that if wormholes exist, you could also use them to get back before you set out. This is a variation of the Grandfather Paradox. Of course, this is a paradox only if you believe you have the free will to do what you like when you go back in time.
But whether the laws of physics allow spacetime to be so warped that a macroscopic body such as a spaceship can return to its own past?? There are many levels on which we can answer this question, but for the time being let me keep it as a secret. I'll disclose the answers in my next blog post!........Keep searching for the answers till then! Thank You!!
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