We aren’t the dinosaurs: we’re the asteroid

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The Sixth Extinction: We’re Not The Dinosaurs, We’re The Asteroid

Yes, humans are probably to blame for the Earth’s sixth mass extinction event, which is wiping out species at a rate 53 times greater than normal.

For The Daily Beast:

Extinction is an inevitable consequence of evolution. Environments change, new species arrive and crowd out the old, any number of factors make a formerly successful species unsuccessful. No less an authority than Charles Darwin wrote in The Origin of Species, “Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character.”

Even without the 19th-century capitalization for emphasis, extinction is a big deal. Earth has experienced at least five major mass extinction events, of which the end of the dinosaurs wasn’t even the largest. (The end of the dinos that hadn’t evolved into birds, of course.) Now the planet is experiencing the sixth mass extinction, and growing evidence points to the culprit. It’s not asteroids or volcanoes or methane this time.

It’s us. [Read the rest at The Daily Beast….]

A multitude of faint and fluffy galaxies

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Scientists Discover Hundreds of Hidden Galaxies

The new type of faint, fluffy galaxy might help resolve a cosmological conundrum

For The Daily Beast:

When we think of galaxies, we tend to focus on the beautiful spirals, like the Milky Way, or possibly the huge elliptical galaxies. However, we know that a lot of galaxies are small, and those are harder to spot. In fact, astronomers have observed far fewer low-mass galaxies than predicted by theory, which has been a puzzle and a problem.

A new discovery might help with the answer. Astronomers using the Subaru telescope in Hawaii found 854 nearly invisible galaxies in the Coma Cluster. These hidden objects are very large—some are roughly the size of the Milky Way—but extremely low density. This new census is a notable increase in the population of the Coma Cluster, which is already a large galaxy cluster. It’s likely that other galaxy clusters could be hiding fluffy faint galaxies too. [Read more in The Daily Beast…]

Emmy Noether and her wonderful theorem

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Mathematician to know: Emmy Noether

Noether’s theorem is a thread woven into the fabric of the science

For Symmetry Magazine:

We are able to understand the world because it is predictable. If we drop a rubber ball, it falls down rather than flying up. But more specifically: if we drop the same ball from the same height over and over again, we know it will hit the ground with the same speed every time (within vagaries of air currents). That repeatability is a huge part of what makes physics effective.

The repeatability of the ball experiment is an example of what physicists call “the law of conservation of energy.” An equivalent way to put it is to say the force of gravity doesn’t change in strength from moment to moment.

The connection between those ways of thinking is a simple example of a deep principle called Noether’s theorem: Wherever a symmetry of nature exists, there is a conservation law attached to it, and vice versa. The theorem is named for arguably the greatest 20th century mathematician: Emmy Noether.

So who was the mathematician behind Noether’s theorem? [Read the rest at Symmetry…]

Why do some want to modify general relativity?

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And yes, I did refer to MOND as “a fungus in the basement of astronomy”.

Do We Need to Rewrite General Relativity?

For NOVA “The Nature of Reality”:

General relativity, the theory of gravity Albert Einstein published 100 years ago, is one of the most successful theories we have. It has passed every experimental test; every observation from astronomy is consistent with its predictions. Physicists and astronomers have used the theory to understand the behavior of binary pulsars, predict the black holes we now know pepper every galaxy, and obtain deep insights into the structure of the entire universe.

Yet most researchers think general relativity is wrong.

To be more precise: most believe it is incomplete. After all, the other forces of nature are governed by quantum physics; gravity alone has stubbornly resisted a quantum description. Meanwhile, a small but vocal group of researchers thinks that phenomena such as dark matter are actually failures of general relativity, requiring us to look at alternative ideas. [Read the rest at NOVA…]

Blogging about science for Forbes Magazine

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As of this week, I will be blogging regularly for Forbes on planetary science, climate change, physics, and math. My first two posts are up; go check them out and please follow my blog!

Why are Pluto’s moons so weird?

Pluto is a strange little world, but its moons are even weirder.

Whether or not you want to call it a “planet”, it’s a body strongly influenced by two other worlds: the giant planet Neptune and its moon Charon. Pluto crosses Neptune’s orbit twice during its long sojourn around the Sun. But Charon (which I pronounce KAR-on, but you’ll also hear SHAR-on and other variations) is the big deal: the moon is more than 10 percent of the mass of Pluto. It exerts such a strong gravitational pull that both objects orbit a spot in empty space between them, and forces Pluto to present one face to Charon, just like Earth forces the Moon to keep the same side faces us. If you lived on the “far side” of Pluto, you’d never see Charon in the sky.

Pluto and Charon together have four much smaller moons: Styx, Nix, Kerberos, and Hydra. We don’t know much about those moons yet: Nix and Hydra were only discovered in 2005, Kerberos was found in 2011, and Styx in 2012. Even in our most powerful telescopes, they appear as dots. (Pluto and Charon aren’t much better off — they look like blurry disks even to the Hubble Space Telescope.) But looking at their orbits around Pluto and Charon, astronomers found something weird.

Those tiny moons dance in tandem. [Read the rest at Forbes…]

New analysis shows Earth is warming faster than we thought

Politicians may dither and talking heads bloviate, but the scientific consensus is clear: climate change is real, humans are responsible, and its effects are already being felt around the world. At the same time, some details are in question, including how fast climate change is increasing and which specific effects we see are due to it as opposed to other sources.

That’s the context for a new paper in Science today from researchers at the National Oceanographic and Atmospheric Administration (NOAA, which is somewhat ironically pronounced “Noah”). Thomas Karl and colleagues took a second look at global surface temperatures — the ordinary temperatures we’re used to seeing on weather news or in our phone apps — and found the official numbers on rising temperatures are too low. To put it another way: the consensus opinion is that we are currently in a global warming “hiatus”, but Karl and coauthors report instead that temperatures are climbing as fast as ever.

As if we didn’t have enough to worry about. [Read the rest at Forbes…]

No quantum foam seen in the cosmic beer glass

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Light from distant black holes doesn’t surf on waves of quantum foam

Strongest check yet on quantum gravity effects in astronomy turns up nothing

For Ars Technica:

Quantum gravity is notoriously slippery. While the Standard Model successfully describes three forces of nature, it doesn’t include gravity, so gravity still has no consistent quantum theory. To make matters worse, gravity is so weak that it’s difficult to probe at the sorts of energies where any minuscule quantum effects would pop out. However, some researchers predict that those tiny effects could accumulate over cosmological distances: light traveling from far-off quasars would be changed by the “quantum foam” of spacetime, producing blurry images in our telescopes—or even making objects seem to disappear.

A new report by E. S. Perlman and colleagues examines the disappearance hypothesis using gamma-ray data from quasars. In particular, they investigated a possibility suggested by the holographic principle, the idea that all the information in the cosmos can be encoded on the two-dimensional boundary that encloses it. Disappointingly for fans of quantum foam, the gamma ray data did not show any measurable fading or blurring of the quasars.

As the authors point out, these results don’t rule out anything general regarding quantum gravity, quantum foam, or the holographic principle. But they do provide the tightest constraint yet on cumulative effects of quantum foam on light traveling across the Universe. [Read the rest at Ars Technica…]