The journey with time continues. In Time; Concept Beyond Your Wall-Clock #part 1 I mentioned the basic concept of time, what it actually is, and most importantly, I told you why it is not bounded within the digits of your wall-clock. I told you about different nature of time, the relation between time and velocity. I left you with a hint on time-travel. Let the journey resume from there.
As we saw, Muons, due to their high velocity, spends only 1 of a million seconds during their journey towards earth, while much more time has passed in earth during the journey. So, if, somehow, a human being is replaced with the muon, can he turns out to be younger than his son/daughter? Well, this is the exact scenario of the movie Interstellar! At some point, science fiction are not just mere fiction!
This, is, some kind of a time travel, theoretically! But, that’s not the only kind of time travel possible. We’ll talk about some other possibilities.
But, before, let me clarify another weird thing of relativity. Spacetime. According to Einstein, there is no independent existence of space, or time. Spacetime is a mathematical model that combines space and time into a single interwoven continuum. Now, why is it necessary? While treating daily life occurrences with Newton’s law, and without the concept of spacetime, nothing wrong is happening apparently!
Well, the thing is, Newtonian laws, and corresponding Eucledian space is perfectly valid for daily life occurrences, as the objects are neither as big as a sun, nor too small, and they do not have a velocity even close to that of light’s. But, in cosmology, the dealing is with huge stars, planets, and meteors and particles with velocity sometimes close to light’s. And there are other weird things like black holes. And as it turns out, Newton;s law can not describe all these. It can not explain the source of fundamental forces like gravitation, and that’s when Einstein came up with is special theory of relativity, and later, general theory of relativity. In his research, Einstein made two revolutionary change. One, he concluded that the velocity of light is the ultimate limit, and it is the ultimate constant. And Two, he suggested that the space, is not just Eucledian space, rather, it is a fabric of spacetime. Here, with the three dimension of space, time adds up to form the 4th dimension. And, the existence of huge planets, stars distorts the fabric, and that is the reason of gravitational pull. You can easily visualize the scenario with daily life incident. Take a bed-sheet, stretch it, now, if a ball or something falls on it, it distorts the stretched sheet, now, if you put any small stuff on the sheet, it will eventually be attracted towards the ball because of the distortion. That is the source of gravitational pull. The only difference is, a gravitational pull will affect the time also because the distorted fabric is of spacetime instead of just space. The distortion made by our daily life objects are so negligible, that we don’t have to take into account all these, and Newtonian mechanics works just fine.
We got another thing, gravitational pull, that is able to affect time! Can we make something out of it to make time travel possible? Yes, we can, theoretically. But the hard thing is to find something with that much gravitational pull to leave a recognizable effect. We’ve got black holes, but that is not the best thing as a time machine, is it?
Another thing is, wormhole. A wormhole or Einstein–Rosen bridge is a hypothetical topographical feature that would fundamentally be a shortcut connecting two separate points in spacetime. A wormhole, in theory, might be able to connect extremely far distances such as a billion light years or more, short distances such as a few feet, different universes, and different points in time. A wormhole is much like a tunnel with two ends, each at separate points in spacetime
A wormhole is like short cut in spacetime. And a what does it mean by a short cut to time? Yes. Time machine.
But the problem is, wormhole’s existence is not yet proved. Further, if it is hard to find one, it is like impossible to make something out of it! Bur, Physics always left a clue. It turns out, weird things like these are not only exclusively for huge planets and stars, in tiny things, like atoms, the scenario is just the same. Inside an atom, Eucledian space no longer exist, and reign of Einstein begins. It is where the states of everything is not certain, they are probabilistic. And, this is the fundamental of quantum theory. Bit, more on these later. Let us focus on weirdness of time, here. Inside the atom, in the subatomic realm, bubbles of weird quantum states are believed to exists, known as quantum foam. Their discovery is the result of Einstein’s brilliance, Quantum Entanglemnt. But, let’s not get too deep in these. The matter of fact is, these quantum foam acts like wormholes, but the thing is, they are very unstable. The only thing that is necessary is to stabilize them, and there we are, with a time machine!
Sounds fun, doesn’t it? But, Physics is a mere fairy tale, which hopes for a wish-granting world! Making the world a wish granting place is not the job of Physicists, it’s now up to engineers. But the hard part is, some of these are theoretically possible, on pen and paper. The real world is a hard place!
We were here to share the concept of time, beyond our daily encounters. I think, I’ve covered as many topics I can! But, I’m a mere science undergrad student, it’s always better to gather the knowledge from the master! And who else other than Stephen Hawking can provide you “everything”? Stephen Hawking’s A Brief History On Time is a masterpiece. Go to the Buy Books section to grab your copy.
Thanks for your time. See you soon!