Long live the work of Emma Noether

A wonderful article at arstechnica tells of the work of a woman Jew in the early 20th century. She lived in Germany in the years leading up to WWII. She had to leave, and came to America. Some of her best work is on Einstein‘s General Theory of Relativity.

Science kind of takes some symmetries for granted. For example, you should be able to perform the same experiment a year later and get the same result. Or you should be able to do it in two places and get the same result. But one of the main laws of physics — conservation of energy — seems to be broken by general relativity. It is possible for a machine to emit gravity waves, and gain energy instead of losing it.

This paradox was solved by Emma Noether who’s theorem proves a connection between symmetries and conservation laws.

It turns out that with general relativity, you may get different results depending on where you are when you perform your experiments. Here on earth, the experiments all happen in very similar circumstances. But in a strong gravitational field, the curvature of space is different, and you can get different measurements. This strange effect is predicted by Einstein’s theories, and Neother’s theorem provides the connection.

New Horizons snaps pictures of Pluto’s small moons

New Horizons is due to get to Pluto in 59 days (closest approach on July 14). It has already taken photos of the small Plutonian moons. We’ve known about Pluto’s main moon Charon since 1978. The Pluto / Charon system is interesting because the barycenter of the two is outside the body of the primary. This means that the center of mass for Pluto and Charon is above the surface of Pluto.

The smaller moons were discovered in 2005 (Nix, Hydra), 2011 (Kerberos), and 2012 (Styx). They are orbiting Pluto over twice this distance of Charon. These are very small with the largest up to 172 km across.

Super strong spider silk

Regular spider silk (you know, what spider webs are made of) is really amazing stuff. For its size, it’s stronger than anything humans can make. But they can really up their game just by being sprayed with water that has carbon nanotubes and graphene flakes in it. That’s all it took to make the spiders weave super strong silk, stronger than anything else.

These guys have found a way to incorporate carbon nanotubes and graphene into spider silk and increase its strength and toughness beyond anything that has been possible before. The resulting material has properties such as fracture strength, Young’s modulus, and toughness modulus higher than anything ever measured.

The researchers don’t know how the spiders manage to incorporate the nanotubes and graphene into their silk, and there isn’t a good way to harvest the resulting fibers to mass produce materials.

NOVA Evolution Lab

What could you possibly have in common with a mushroom, or a dinosaur, or even a bacterium? More than you might think. In this Lab, you’ll puzzle out the evolutionary relationships linking together a spectacular array of species. Explore the tree of life and get a front row seat to what some have called the greatest show on Earth. That show is evolution.

Nova has made a cool game where you can explore how different species are related to each other. It’s over at NOVA Evolution Lab. It’s a cool game where you drag different species to create a phylogenetic tree. You also have to identify what characteristics cause the different branches of the tree.

Google Maps for the body

Australian scientists have managed to get imaging of the human body at many different levels. This is giving views from joints to the cellular level.

“For the first time we have the ability to go from the whole body down to how the cells are getting their nutrition and how this is all connected,” said Professor Knothe Tate. “This could open the door to as yet unknown new therapies and new preventions.”

This kind of imagery involves terabyte sized data sets, and the Google Maps software helps them use it effectively.