Dark Matter not so dark after all?

We’ve never seen Dark Matter. But we know that there isn’t enough matter in galaxies to hold them together, so there must be something adding more gravity; that’s what we call dark matter. The problem is that the only effect it seems to have is gravitational. Light goes right through it. For all we know, matter can go right through it.

But it’s may not be quite so mysterious after all. Astronomers may have observed dark matter having an effect beyond just gravity. Researchers have been studying 4 galaxies colliding about 1.3 billion light years away. It seems that a dark matter clump is lagging behind its galaxy by about 5,000 light years. This is predicted if dark matter interacts with other forces. It seems the friction from the collision would slow the dark matter down.

Astronomers can see the dark matter clump because they are viewing the clump through a gravitational lens from galaxies between us and the galaxies being studied.

Brain Dissections

While I teach general science, my schools Gifted and Talented teacher goes into more advanced work with some of the students. Today she brought in a biology expert to do sheep brain dissection in my classroom.

Students were finding the parts of the brain they’ve learned about, from the pituitary gland to the olfactory lobes to the optic nerve crossover. Looking at the gray matter and the white matter.

Some parents came in to do this with their kids. Most kids had fun, but one or two were kind of squeamish.

Sheep brain

Sheep brain

The Neutron has more mass than the Proton

80 years ago scientists discovered the neutron. The masses of the two nucleons, the neutron and the proton, are so close that in middle school it doesn’t make sense to distinguish the difference. Last week scientists have determined that the neutron is ≈0.14% more massive than the proton. This implies that the down quark is slightly more massive than the up quark.

If the difference is masses were slightly different, our universe would be very different, with not as much hydrogen, not many heavy metals, or more.

Man-made earthquakes

Many places in the world get earthquakes. The very low magnitude ones are surprisingly common. But the high magnitude ones are uncommon. But when the number of earthquakes increases dramatically, it’s time to get worried about what’s going on.

The New Yorker has an article on the number of earthquakes increasing in Oklahoma. In 2008 there were one or two magnitude 3.0+ earthquakes each year. Now, it’s one or two magnitude 3.0+ earthquakes each day. What’s changed? What could be causing this? The answer is fracking. Pumping a slurry of water, sand, and chemicals into the earth at high pressure helps release natural gas.

William Ellsworth, a research geologist at the United States Geological Survey, told me, “We can say with virtual certainty that the increased seismicity in Oklahoma has to do with recent changes in the way that oil and gas are being produced.” Many of the larger earthquakes are caused by disposal wells, where the billions of barrels of brackish water brought up by drilling for oil and gas are pumped back into the ground. (Hydraulic fracturing, or fracking—in which chemically treated water is injected into the earth to fracture rocks in order to access oil and gas reserves—causes smaller earthquakes, almost always less than 3.0.) Disposal wells trigger earthquakes when they are dug too deep, near or into basement rock, or when the wells impinge on a fault line. Ellsworth said, “Scientifically, it’s really quite clear.”

Humanity is causing more and stronger earthquakes. What are we going to do about it?

Why do we have allergies?

Allergies are really annoying, and sometimes deadly. They are caused by our immune system overreacting to a stimulus and causing the allergy symptoms, sometimes even death. So, how is this an evolutionary advantage? Why hasn’t natural selection removed this?

A good article at Gizmodo explains how a Russian researcher, Ruslan Medzhitov, has studied allergies and the immune response.

Allergies make a lot more sense in terms of evolution when seen as a home-alarm system, argues Medzhitov. Toxic chemicals, whether from venomous animals or plants, have long threatened human health. Allergies would have protected our ancestors by flushing out these chemicals. And the discomfort our ancestors felt when exposed to these allergens might have led them to move to safer parts of their environment.

It looks like the allergic response isn’t triggered by the presence of an allergen, but when that allergen starts harming the body–destroying cells. Essentially, allergies are your body’s way of trying to remove the allergen. Coughing, itching, sneezing, and tears are all ways that bodies try to get things out of the body. More research needs to be done on this.

Sitting on Cullen’s lab bench is a plastic box that houses a pair of mice. There are dozens more of these boxes in the basement of their building. Some of the mice are ordinary, but others are not: using genetic engineering techniques, Medzhitov’s team has removed the animals’ ability to make IgE. They can’t get allergies.

Medzhitov and Cullen will be observing these allergy-free mice for the next couple of years. The animals may be spared the misery of hay fever caused by the ragweed pollen that will inevitably drift into their box on currents of air. But Medzhitov predicts they will be worse off for it. Unable to fight the pollen and other allergens, they will let these toxic molecules pass into their bodies, where they will damage organs and tissues.

This would show that allergies are helpful to the body and there would be selective pressure for allergies as an adaptation.

Harry Potter and the Methods of Rationality

Everyone knows that Harry Potter is a muggle born wizard who learns lots of magic at Hogwarts. Harry Potter and the Methods of Rationality is a fanfic that redoes HP in a different universe where Harry’s adoptive parents love him, and have taught him science. Harry is already an extremely intelligent rationalist at the start, and the existence of magic throws him for quite a loop. He tries to apply the principles of science and logic to magic. I’m currently reading it (and enjoying it thoroughly), though it does get quite advanced in the philosophy of science.

Harry ends up in Ravenclaw, and (gasp) is friends with Draco.

“But let us talk of happier matters,” said the green-shadowed figure. “Let us talk of knowledge and of power. Draco Malfoy, let us talk of Science.”

… OK. Most of it is better than that. 🙂

“Science isn’t for convincing anyone that the blood purists are right. That’s politics! The power of science comes from finding out the way Nature really is [and] that can’t be changed by arguing! What science can do is tell us how blood really works, how wizards really inherit their powers from their parents, and whether Muggleborns are really weaker or stronger -“

There’s also a website that has detailed information on the things Harry knows.