Posted on 12/13/2018 2:07:09 PM PST by ETL
The concept of time travel has always captured the imagination of physicists and laypersons alike. But is it really possible? Of course it is. We're doing it right now, aren't we? We are all traveling into the future one second at a time.
But that was not what you were thinking. Can we travel much further into the future? Absolutely. If we could travel close to the speed of light, or in the proximity of a black hole, time would slow down enabling us to travel arbitrarily far into the future. The really interesting question is whether we can travel back into the past.
I am a physics professor at the University of Massachusetts, Dartmouth, and first heard about the notion of time travel when I was 7, from a 1980 episode of Carl Sagan's classic TV series, "Cosmos." I decided right then that someday, I was going to pursue a deep study of the theory that underlies such creative and remarkable ideas: Einstein's relativity. Twenty years later, I emerged with a Ph.D. in the field and have been an active researcher in the theory ever since.
Now, one of my doctoral students has just published a paper in the journal Classical and Quantum Gravity that describes how to build a time machine using a very simple construction.
Closed time-like curves
Einstein's general theory of relativity allows for the possibility of warping time to such a high degree that it actually folds upon itself, resulting in a time loop. Imagine you're traveling along this loop; that means that at some point, you'd end up at a moment in the past and begin experiencing the same moments since, all over again – a bit like deja vu, except you wouldn't realize it. Such constructs are often referred to as "closed time-like curves" or CTCs in the research literature, and popularly referred to as "time machines." Time machines are a byproduct of effective faster-than-light travel schemes and understanding them can improve our understanding of how the universe works.
Over the past few decades well-known physicists like Kip Thorne and Stephen Hawking produced seminal work on models related to time machines.
The general conclusion that has emerged from previous research, including Thorne's and Hawking's, is that nature forbids time loops. This is perhaps best explained in Hawking's "Chronology Protection Conjecture," which essentially says that nature doesn't allow for changes to its past history, thus sparing us from the paradoxes that can emerge if time travel were possible.
Perhaps the most well-known amongst these paradoxes that emerge due to time travel into the past is the so-called "grandfather paradox" in which a traveler goes back into the past and murders his own grandfather. This alters the course of history in a way that a contradiction emerges: The traveler was never born and therefore cannot exist. There have been many movie and novel plots based on the paradoxes that result from time travel – perhaps some of the most popular ones being the "Back to the Future" movies and "Groundhog Day."
Exotic matter
Depending on the details, different physical phenomena may intervene to prevent closed time-like curves from developing in physical systems. The most common is the requirement for a particular type of "exotic" matter that must be present in order for a time loop to exist. Loosely speaking, exotic matter is matter that has negative mass. The problem is negative mass is not known to exist in nature.
Caroline Mallary, a doctoral student at the University of Massachusetts Dartmouth has published a new model for a time machine in the journal Classical & Quantum Gravity. This new model does not require any negative mass exotic material and offers a very simple design.
Mallary's model consists of two super long cars – built of material that is not exotic, and have positive mass – parked in parallel. One car moves forward rapidly, leaving the other parked. Mallary was able to show that in such a setup, a time loop can be found in the space between the cars.
So can you build this in your backyard?
If you suspect there is a catch, you are correct. Mallary's model requires that the center of each car has infinite density. That means they contain objects – called singularities – with an infinite density, temperature and pressure. Moreover, unlike singularities that are present in the interior of black holes, which makes them totally inaccessible from the outside, the singularities in Mallary's model are completely bare and observable, and therefore have true physical effects.
Physicists don't expect such peculiar objects to exist in nature either. So, unfortunately a time machine is not going to be available anytime soon. However, this work shows that physicists may have to refine their ideas about why closed time-like curves are forbidden.
Explore further: Stephen Hawking's final book suggests time travel may one day be possible – here's what to make of it
Yo Mama So FAT....
:)
"You are watching a tape backwards. You see the end first. You can even watch the tape in 10x speed. Or, better yet, view the entire tape at once as a series of still photos and sounds on a single panel. The people on the tape cannot do this. Each following moment is a surprise to them right up to the end, but not to you. Because you are outside the tape. You are the author or the audience. You are not limited by five senses to experience only what is revealed moment by moment. You have a different point of references and are capable of vastly greater senses. While watching the tape, you are not restricted by the artificial construct we call "time". You do not have to "remember" anything. The word has no meaning to you as you can experience what those on the tape consider a memory as it happened at any point you wish."
“You are watching a tape backwards.”
Note To Self:
Send regrets to so_real as you won’t be attending his “Movie Night Party.”
Yes, and our relativistic mass would approach infinity as we accelerated towards c as well. Since force=mass * acceleration, the amount of force required to further accelerate a mass that is approaching infinity would also approach infinity, which means you would require infinite energy to achieve that force.
Thus, no massive object can be accelerated to the speed of light, unless you somehow had an infinite energy source.
How about localization? Maybe there is a way to create an artificial universe in which all of its mass is contained within.
What will be the charge for 'carry on'?
Nothing because you’ll have a tartus that can fit into your pocket.
The problem with this esteemed professor is that he is myopic. He needs a new set of glasses because the universe looks nothing like he assumes it to be. It really doesn’t.
Time travel is possible as there is a variable missing from Einstein’s equation.
Time is not a function of the speed of light, but is a function of the frequency of consciousness divided by the spped of light.
Consciousness is the most powerful variable in the equation as it is the source of all energy and mass.
Is the term “infinite mass” suppose to mean anything?
You do not need exotic infinite mass to move forward in time.
For forward time travel, we only need to stop our perception of forward travel while we are doing it, and stop, or slow the chemical processes of aging while it is happening.
This is essentially what happens with the Rip Van Winkle legend, and all speculations of suspended animation.
There is no physical law that prevents suspended animation from being achieved. It is essentially a difficult problem in chemical and biological engineering. We do it for short periods with cooling the body while performing some operations.
The hard part of time travel is traveling backward in time. That is a very difficult, maybe impossible, problem.
Infinite Mass,
Time Loops
and
Cher!
I’m dizzy,
Nauseous
and l need
a chair!
Ew.
One would have to change the entire universe, from its present volume to its past, and future volumes.
It won’t happen any time soon.
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