Tag: Theory

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