Tag: Theory

Stephen Hawking’s Final Paper Proposes Way To Detect The ‘Multiverse’

Stephen Hawking’s final research paper could help astronomers find evidence that our universe is just one among many in a larger “multiverse,” according to media reports.

The famed cosmologist, who died last week at the age of 76, is lead author of a study called “A Smooth Exit from Eternal Inflation?” which was originally submitted to an unnamed journal last July.

On March 4 — just 10 days before Hawking’s death — his co-author, Thomas Hertog, a professor of theoretical physics at KU Leuven University in Belgium, submitted a revised version of the manuscript for further review, according to British newspaper The Sunday Times.

The inflation referenced in the paper’s title is the incredible expansion of space-time theorized to have occurred in the first few moments after the Big Bang, which created the universe.

Many physicists believe that this dramatic ballooning wasn’t limited to our neck of the cosmic woods but rather happened repeatedly, spawning multiple universes — perhaps an infinite number of them.

Not everyone is so enthusiastic about the paper’s potential.

For example, Neil Turok, the director of the Perimeter Institute for Theoretical Physics in Canada, told The Sunday Times, “I remain puzzled as to why [Hawking] found this picture interesting.

However it’s ultimately received, the manuscript — which you can read for free at the online preprint site arXiv.org — is a reminder that Hawking was a deep thinker committed to tackling some of the universe’s biggest mysteries.

He will be missed a great deal, by his colleagues and the general public alike.

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Pass it on: Popular Science

Stephen Hawking Says He Knows What Happened Before The Big Bang

At the time of the Big Bang, all the matter in the universe was smooshed into an incredibly hot, infinitely dense speck of matter.

But what happened before that? It turns out, famed physicist Stephen Hawking has an answer, which he gave in an interview with his almost-as-famous fellow scientist, Neil deGrasse Tyson.

Hawking discusses these ideas and others on the series finale of Tyson’s “StarTalk” TV show, which airs this Sunday (March 4) at 11 p.m. ET on the National Geographic Channel.

Hawking’s answer to the question “What was there before there was anything?” relies on a theory known as the “no-boundary proposal.

To understand the theory better, grab your universal remote (that is, your remote that controls the universe), and hit Rewind. As scientists know now, the universe is constantly expanding.

As you move backward in time, then, the universe contracts. Rewind far enough (about 13.8 billion years), and the entire universe shrinks to the size of a single atom, Hawking said.

This subatomic ball of everything is known as the singularity (not to be confused with the technological singularity during which artificial intelligence will overtake humans).

Inside this extremely small, massively dense speck of heat and energy, the laws of physics and time as we know them cease to function.

Put another way, time as we understand it literally did not exist before the universe started to expand. Rather, the arrow of time shrinks infinitely as the universe becomes smaller and smaller, never reaching a clear starting point.

According to TechTimes, Hawking says during the show that before the Big Bang, time was bent — “It was always reaching closer to nothing but didn’t become nothing,” according to the article.

Essentially, “there was never a Big Bang that produced something from nothing. It just seemed that way from mankind’s point of perspective.

In in a lecture on the no-boundary proposal, Hawking wrote: “Events before the Big Bang are simply not defined, because there’s no way one could measure what happened at them.

Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang.”

This isn’t the first time Hawking has discussed this theory. He previously delivered lectures on the topic and starred in a free documentary about it, available on YouTube.

Tune into StarTalk on Sunday to hear Tyson and Hawking delve deeper on the subject, as well whether Isaac Newton would be more excited to learn about black holes or Tinder.

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Pass it on: Popular Science

Has The Mystery Of How The Moon Was Formed Finally Been Solved?

The object that smashed into earth to create the moon was far smaller than thought, a new simulation has shown.

Researchers at the Paris Institute of Earth Physics tested over two billion combinations of parameters to try and solve the mystery of how the moon formed.

The key, they concluded, was an impact with a body roughly one-tenth the mass of Earth.

Astronomers have long suspected that the moon was created when a giant protoplanet called Theia struck the newly formed Earth – a theory first put forward in the 1970s.

It says the huge collision created a vast cloud of debris, which coalesced into the moon.

However, until now, astronomers have not been able to explain how this left the moon and Earth chemically identical.

This led to two other ideas, which predicted dramatically different masses for the impact object.

In one, two half-Earths merged to form the Earth-moon system, and in the second, Theia was a small, high-velocity projectile that smacked into a larger and fast-spinning young Earth.

The researchers ran more than 2 billion simulations of the crash, and found an impactor larger than 15 per cent of the mass of Earth, couldn’t produce the chemistry we see in Earth’s mantle, instead leading to a mantle far too rich in nickel and cobalt.

This was known as the giant-impact hypothesis, or the Big Splash.

Now, a simulation created by researchers from Southwest Research Institute in Colorado has found that after this massive impact, there was a long period when leftover mini planets called planetesimals pounded the Earth.

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Pass it on: New Scientist

The Big Bang: What Really Happened At Our Universe’s Birth?

It took quite a bit more than seven days to create the universe as we know it today.

Our universe was born about 13.7 billion years ago in a massive expansion that blew space up like a gigantic balloon.

That, in a nutshell, is the Big Bang theory, which virtually all cosmologists and theoretical physicists endorse. The evidence supporting the idea is extensive and convincing.

We know, for example, that the universe is still expanding even now, at an ever-accelerating rate.

Scientists have also discovered a predicted thermal imprint of the Big Bang, the universe-pervading cosmic microwave background radiation.

And we don’t see any objects obviously older than 13.7 billion years, suggesting that our universe came into being around that time.

All of these things put the Big Bang on an extremely solid foundation,” said astrophysicist Alex Filippenko of the University of California, Berkeley. “The Big Bang is an enormously successful theory.

So what does this theory teach us? What really happened at the birth of our universe, and how did it take the shape we observe today?

The beginning

Traditional Big Bang theory posits that our universe began with a singularity — a point of infinite density and temperature whose nature is difficult for our minds to grasp.

However, this may not accurately reflect reality, researchers say, because the singularity idea is based on Einstein’s theory of general relativity.

The problem is, there’s no reason whatsoever to believe general relativity in that regime,” said Sean Carroll, a theoretical physicist at Caltech.

It’s going to be wrong, because it doesn’t take into account quantum mechanics. And quantum mechanics is certainly going to be important once you get to that place in the history of the universe.

So the very beginning of the universe remains pretty murky. Scientists think they can pick the story up at about 10 to the minus 36 seconds one trillionth of a trillionth of a trillionth of a second after the Big Bang.

Inflation was the ‘bang’ of the Big Bang,” Filippenko said. “Before inflation, there was just a little bit of stuff, quite possibly, expanding just a little bit. We needed something like inflation to make the universe big.

During inflation, dark energy made the universe smooth out and accelerate. But it didn’t stick around for long.

Scientists don’t know what might have spurred inflation. That remains one of the key questions in Big Bang cosmology, Filippenko said.

Cosmologists and physicists are working hard to refine their theories and bring the universe’s earliest moments into sharper and sharper focus.

But will they ever truly know what happened at the Big Bang?

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Pass it on: New Scientist