Einstein’s Theory of General Relativity

Scientists find Time Travel is mathematically POSSIBLE

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Mathematically, time travel is possible. Scientists have created a new mathematical model that dictates how time travel is theoretically possible. Experts used Einstein’s Theory of General relativity as basis for a hypothetical device which they named a Traversable Acausal Retrograde Domain in Space-time (TARDIS).

In other words, they’ve come up with a mathematical model of a theoretical time machine box that has the ability to move back and forth through space and time.

For centuries have humans imagined traveling in time. This idea resulted in countless movies, series and books produced and science fiction seems to have figured out everything there is about Time Travel.  But now scientists decided to see whether they could learn something more about time travel and whether this is just an idea possible in science fiction.

 “People think of time travel as something as fiction. And we tend to think it’s not possible because we don’t actually do it,” said Ben Tippett, a physicist and mathematician from the University of British Columbia, said in a UBC news release, adding “But, mathematically, it is possible.”

What Tippett and his colleague from University of Maryland astrophysicist David Tsang created was a mathematical formula based on Einstein’s General Relativity theory to show how Time Travel is in fact possible, at least in theory.

 According to the abstract of the scientific paper, which was published in the journal Classical and Quantum Gravity, “we present geometry which has been designed to fit a layperson’s description of a ‘time machine.’ It is a theoretical box which allows those within it to travel back and forth through time and space, as seen by an external observer.”

Graciously, they’ve named it TARDIS—which stands for Traversable Acausal Retrograde Domain in Space-time.

Tippet further explained how: “My model of a time machine uses the curved space-time to bend time into a circle for the passengers, not in a straight line. That circle takes us back in time.”

In other words, their newly formulated model ‘assumes’ how time could curve around high-mass objects just as physical space does in the universe.

Tippet and Tsang refer to their TARDIS as a space-time geometry “bubble” that has the ability to move fast than the speed of light. They explain in their paper how: “It is a box which travels ‘forwards’ and then ‘backwards’ in time along a circular path through space-time.”

“Delighted external observers would be able to watch the time travelers within the box evolving backward in time: un-breaking eggs and separating cream from their coffee,” explain scientists in their paper.

But don’t get all excited, it’s still not possible to build—at least not yet.

“While is it mathematically possible, it is not yet possible to construct a space-time machine because we need materials—which we call exotic matter—to bend space-time in these impossible ways, but they have yet to be discovered,” Tippet explained.

Physicists say they’ve found a way to detect naked singularities… if they exist.

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But are we ready?

 

Black holes are weird: insanely dense objects that are crammed into such a small space they cause space-time to distort and the laws of physics to break down into a singularity.

Fortunately, the Universe shields us from this weirdness by wrapping black holes in event horizons. But now, physicists say they’ve found a way we could detect something even more extreme – a naked singularity – and most likely bend the laws of physics in the process.

 “A naked singularity, if such a thing exists, would be an abrupt hole in the fabric of reality – one that would not just distort space-time, but would also wreak havoc on the laws of physics wherever it goes and lead to a catastrophic loss of predictability,” explains Avaneesh Pandey for IB Times.

If that sounds a little too confronting, don’t worry, this whole study is purely theoretical, and is hinged on one very big assumption – that naked singularities actually exist in our Universe, something that scientists have never confirmed.

But according to Einstein’s theory of general relativity at least, and our best computer models to date, naked singularities are possible.

So, what are they? A singularity can form when huge stars collapse at the end of their lives into regions so small and dense, physics as we know it fails to explain what could happen there.

There are two general laws of physics that govern our understanding of reality: quantum mechanics, which explains all the small stuff, such as the behaviour of subatomic particles; and general relativity, which describes the stuff we can see, such as stars and galaxies.

When applied to singularities, both these schools of thought predict different and incompatible outcomes.

 And we’ve never really had to deal with that conundrum, because all the singularities we know of are inside black holes, wrapped in an event horizon from which not even light can escape – or at the very birth of our Universe, shrouded by radiation we can’t see past. Out of sight, out of mind, right?

But naked singularities are theoretical singularities that are exposed to the rest of the Universe for some reason.

Below you can see an illustration of a black hole wrapped in its event horizon (dotted line) on the left, and a naked singularity on the right. The arrows indicate light, which would be able to escape a naked singularity, but not a black hole.

canweseeasin

Assuming they do exist, the big question then is how would we be able to distinguish a naked singularity from a regular black hole, and this is where the new study comes in.

Researchers from the Tata Institute of Fundamental Research in India have come up with a two-step plan based on the fact that singularities, as far as we know, are rotating objects, just like black holes.

According to Einstein’s theory of general relativity, the fabric of space-time in the vicinity of any rotating objects gets ‘twisted’ due to this rotation. And this effect causes a gyroscopic spin and makes the orbits of particles around the rotating objects ‘precess‘, or change their rotational axis.

You can watch the hypnotic precession of a gyroscope below to see what we mean – its axis is no longer straight:

Gyroscope precession

Based on this, the researchers say that we could figure out the nature of a rotating objects by measuring the rate at which a gyroscope precesses – its precession frequency – at two fixed points close to the object.

According to the new paper, there are two possibilities:

  1. The precession frequency of the gyroscope changes wildly between the two points, which suggests the rotating object in question is a regular black hole.
  2. The precession frequency changes in a regular, well-behaved manner, indicating a naked singularity.

Obviously getting a gyroscope close enough to a black hole to perform these experiments isn’t exactly easy.

But that’s okay, because the team has also come up with a way to observe the same effect from here on Earth – measuring the precession frequencies of matter falling into either black holes or naked singularities using X-ray wavelengths.

“This is because the orbital plane precession frequency increases as the matter approaches a rotating black hole, but this frequency can decrease and even become zero for a rotating naked singularity,” the team’s press release explains.

Again, we have to make it clear that all of this is wildly speculative at this time – we have never found any candidate naked singularities, and we’re only just beginning to truly understand regular black holes.

It’s also worth noting that last week, another team of researchers suggested that even if naked singluarities exist, strange quantum effects could keep them hidden from us.

So there’s definitely no consensus right now on whether we’ll ever get the chance to study naked singularities.

And that’s not a terrible thing for now, because are we really ready to observe what goes on at the edge of our Universe?

Maybe, in our lifetime, we’ll find out.

Source:http://www.sciencealert.com

Everything You Should Know About Einstein’s Theory of General Relativity in Under Three Minutes

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Yes, we all know the names of Einsteins various theories, but how much do you really know about what they mean and how they work? You may not have to know the ins and outs of the theory of general relativity to get through your day-to-day life, but it’s always there in the background shaping the spacetime around you. Might as well know how it works.

In a video for Fusion, Walter Isaacson—biographer not only for Albert Einstein but alsoBenjamin Franklin and more recently, Steve Jobs—does a quick run-through of the theory of general relativity in language anyone could understand and explains how it establishes that gravity and acceleration are basically the same thing. And it only takes three minutes! Give it a watch, you’ll be a better, smarter person for it.

watch the video. URL:https://youtu.be/05L5F4GwOqM