Leading Harvard physicist has a radical new theory for why humans exist

[astr0144]

Leading Harvard physicist has a radical new theory for why humans exist.


Where do we come from? Well, it depends on who you ask.
For example, an astrophysicist might say that the chemical components of our bodies were first forged in the nuclear fires of stars.

On the other hand, an evolutionary biologist might look at the similarities between our DNA and that of other primates' and conclude we evolved from apes.

Lisa Randall, a theoretical physicist at Harvard University, has a different, and novel answer, which she describes in her latest book "Dark Matter and the Dinosaurs."

Randall has written other popular science books including the New York Time's bestseller "Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions." Her studies at Harvard explore theoretical particle physics and cosmology.

In her latest book, she posits that the extinction of the dinosaurs — necessary for the emergence of humans — is linked to dark matter. Dark matter is the mysterious, invisible matter that astronomers estimate makes up 85% of all matter in our universe.

One species' extinction is another's head start



View gallery
.An artistic life reconstruction of a new horned dinosaur scientists named Regaliceratops peterhewsi in the paleoenvironment of the Late Cretaceous of ...

Paleontologists largely agree that about 66 million years ago a giant, 9-mile-long celestial body — likely a comet — struck Earth. The impact wiped out 75% of species across the planet, including most of the dinosaurs.
Amongst the survivors were small primates. Over the next 66 million years these primates diversified, grew larger, learned to walk on two legs, and developed large brains, which they eventually used to invent pizza delivery.

So what caused that giant space rock to collide with our planet in the first place and give primates a chance to thrive?

It could just be chance — or luck, depending on your perspective — but Randall would disagree with both of these ideas.




View gallery
.dark_matter___the_dinos

In her book, Randall describes a dark, pancake-shaped patty of densely packed dark matter within our galaxy that could be responsible for our emergence as a species.
Dark matter has never been directly detected. However, there is enough evidence for its immense gravitational influence on our universe that the vast majority of the scientific community agrees that dark matter is a form of mysterious matter that we can neither see or touch, but that nevertheless must permeate the cosmos.

Generally, dark matter tends to be concentrated in large halos around galaxies like giant bubbles. But Randall thinks that there could also be a so-called dark disc amidst the stars, planets, and gas clouds in our galaxy.

Beware the dark disc

If there is dark matter in Randall's hypothetical disc, then it stands to reason that the disc has a powerful gravitational influence on the objects around it — including our solar system.

But our solar system is not always near the disc, which is the crux of Randall's theory.

As the solar system revolves around the center of the Milky Way — the same way Earth revolves around the sun — it moves up and down, or oscillates, through the plane of our galaxy. And the rate of this oscillation is very intriguing.

Below is an illustration of our solar system's oscillation where the orange dot in the lower left rectangle is our sun and the black line at the center is the dark disc:




View gallery


A team of astronomers made a rough estimate of this oscillation rate near the turn of this century, calculating that our solar system passes through the plane of the Milky Way about once every 32 million years, which means if there's a dark disc, we pass through that at the same rate.
Interestingly, there's evidence to suggest that mass extinctions in Earth's past happened within this time frame, or about once every 25 to 35 million years.

It's this similarity between the rate of mass extinction rates and the rate of our solar system's oscillation through the galaxy that made Randall and her Harvard colleague Matthew Reece first suggest the link in scientific paper published in the journal Physical Review Letters last year, and that Randall explores more in her book.

Randall hypothesizes that when we're passing through the dark disc, the gravity from the dark matter within influences the outer region of our solar system, called the Oort cloud.

The Oort cloud, illustrated below just right of center, sits about two light years from the sun and is thought to contain billions of icy objects at least 12 miles wide.



View gallery
_Voyager_1_Goes_Interstellar

If something 12 miles wide hit Earth today, it would mean the end of life as we know it. And Randall thinks that's exactly what happened to the dinosaurs 66 million years ago that opened the door for widespread primate evolution.

Prove it




View gallery
.dark matter
(NASA Goddard Spaceflight Center)
Dark matter is illustrated here as the fog between galaxies.

While it's impossible to wind back the clock, proving the existence of the dark disc would greatly advance Randall's theory.
She's tried to do so by looking at the speed and direction of stars in our galaxy. If stars moved in ways that couldn't be explained by the amount of ordinary, visible matter around them, then it could suggest the presence of the dark disc.

But that's a very tall order. There are about 100 billion stars in the Milky Way, and hunting dark matter is notoriously tricky.

We have a dozen or so functioning detectors underground, on Earth's surface, and in space — and none of them has yet managed to sniff out a dark matter particle. If they do, it would be a significant step toward supporting Randall's hypothesis.

In her concluding remarks, Randall writes:

"In some global sense, we are all descendants of Chicxulub [the town where the dinosaur-killing meteor impacted]. It's a part of our history that we should want to understand. If true, the additional wrinkle presented in this book would mean that not only was dark matter responsible for irrevocably changing our world, but also that some of it played a crucial role in allowing our existence."



http://finance.yahoo.com/news/leading-harvard-physicist-radical-theory-160000092.html

[astr0144]

Life on Earth may have started almost instantaneously.



You might be inclined to think that something as complex as life should be rare, and that it probably took a very long time to come into existence.

But two new pieces of evidence suggest that life beyond Earth might be more likely than we think, and that it began on Earth almost instantaneously — at least on a geological time scale.

Last month, scientists uncovered evidence that life appeared on Earth 300 million years earlier than we previously thought. They found fossils in Western Australia that date back 4.1 billion years.

That means that after the Earth formed, it took only 4 million years for life to get cranking. Four million years is really just the blink of an eye compared to the planet's 4.5-billion-year existence (that's only about 0.1% of the Earth's life so far).

"Life on Earth may have started almost instantaneously," one of the lead researchers, Mark Harrison, said in a press release. "With the right ingredients, life seems to form very quickly."

And speaking of the right ingredients, scientists just uncovered evidence that our planet has had water on it since the very beginning. Water is essential to life — everywhere that we find water on Earth, we find life.

It's so critical that many astronomers use a "follow the water" mantra to guide them in their search for life beyond Earth. That's why scientists are pushing for more missions to Europa and Enceladus — two moons that we know have water, and therefore may support life.

But the origin of Earth's water has always been a mystery to scientists. The popular theory is that it was carried here by asteroids that pummeled Earth and left the moon heavily cratered about 3.9 billion years ago, according to NASA. But this new discovery seems to rule out that theory as the initial source of Earth's water.

The research was published on November 13 in the journal Science.

A team of researchers examined lava that bubbled up from deep within the Earth's mantle on Baffin Island in Canada and the Holuhraun lava field in Iceland to look for signs of water.



Holuhraun lava field in IcelandMagnús Tumi Guðmundsson

When an eruption happens, lava flow can carry chunks of rock up from deep within the Earth. The lava flow quickly hardens, and scientists are able to study its composition.

Lava flow on Baffin Island pulled up rock from deep within the Earth that dates back to 4.5 billion years ago. Its chemical composition is preserved deep underground, so it's a pristine record of the material that first formed Earth.

In this case, the researchers were looking for rock with hydrogen and deuterium — a heavier type of hydrogen. Their presence is a chemical signature of water, and the ratio of the two can help researchers trace the origin of the water. In the rock that the researchers tested, the ratio was close to what we see in water-carrying chunks of asteroid.

That means that the Earth may have formed the same way asteroids did. Scientists already know there was water present in the cloud of dust that spawned our solar system. Scientists think that water-soaked dust coalesced and hardened to form asteroids and later planets. So some water has possibly been on Earth since it first formed.

Put together, these findings have profound implications for the likelihood of life beyond Earth.

It suggests it might be easier for life to arise than previously thought. And some of the other planets in our solar system and beyond the Milky Way probably also formed out of water-soaked dust. That means they all had one of the most important ingredients for life from the very beginning.

Some scientists are skeptical of this new water research, but if it's true, "that would make habitable worlds much more likely," Horst Marschall, a geoscientist at Woods Hole Oceanographic Institution, told New Scientist.

http://uk.businessinsider.com/earth-life-started-instantaneously-2015-11?r=US&IR=T

[astr0144]

Scientists may have discovered the origin of Earth's water.

Researchers from the University of Hawaii believe that they have discovered the origin of Earth's water.



New data suggests that Earth had water from the beginning of its formation.

For many years, scientists were uncertain whether water was present when our planet formed, or if it was carried by comets and asteroids at a later time.

By analyzing rocks from Baffin Island in Canada, the researchers were able to produce the most convincing piece of evidence in favor of the native water hypothesis.

The rocks come directly from the mantle, and they have not been affected by material from the crust. In them, the researchers found glass crystals that have trapped small droplets of water. That water has the same composition of the water that is now present on our planet.

Water is made of oxygen and hydrogen, and hydrogen is often found in three forms, called isotopes: normal hydrogen, deuterium, and tritium. Water that is formed by oxygen and deuterium is called heavy water.

By studying the composition of different bodies in the solar system, the researchers discovered that they tend to have a very distinct ratio between normal water and heavy water. Comets have shown a significantly higher ratio of heavy water to normal water.

The researchers are not discounting the comet and asteroid theory for water, but say it is not a necessity to explain how we got our oceans.

"We cannot rule out the addition of water to Earth's surface after its formation (i.e. via comets and asteroids), but our data suggests that Earth had water from the very beginning of its formation, so a large amount of water addition later was not necessarily needed to produce our oceans," Dr. Lydia Hallis, lead author of the study, told IFLScience.

"We can say that the water we measured from the deep mantle is highly unlikely to have been added in this way, because cometary and asteroidal impacts would not have been large enough or powerful enough to affect the deep mantle thousands of kilometers beneath the surface, and previously reported geochemical data suggests the source regions for our rocks have not been disturbed in about 4.5 billion years," she said.

The study, published in Science, provides important clues on the widespread presence of water in the solar system. "Our research suggests that rocky bodies form with their water, and so we would expect to find that many of these bodies are water rich (as indeed we are finding with new images and data from Mars, the Moon, and asteroids)," added Dr. Hallis. "This research shows how vital sample return missions to asteroids and comets really are, to allow us to study the chemistry of these bodies and determine how and when they formed."

http://uk.businessinsider.com/scientists-may-have-discovered-the-origin-of-earths-water-2015-11?r=US&IR=T