Physics

In order to conceptually bridge the Wigner MATH-PHYSICS GAP, it is helpful to see how deeply embedded quantitative and structural properties are in the physical world. The phase space approach is helpful, and a vid on how colliding blocks compute digits of pi (under ideal circumstances) will help. The vid: It helps to look at some screenshots: In this first shot (from a part 1 vid) we see a setup where we have a frictionless plane with a rigid wall to the left and two masses that collide. On the first hitting the second, it will hit and bounce back (elastically) from the wall. A second collision with the first block follows and rebound from the wall. This will continue Read More ›

Twenty years ago, astronomers couldn’t find enough satellite galaxies orbiting the Milky Way. Now there seem to be too many. Some information seems to be missing. A possible solution is that many of these galaxies are dwarfs formed by dark matter: Most cosmologists believe that dark-matter particles are “cold,” meaning that they move slowly. Because of this, they can coalesce into numerous tiny halos, providing scores of places where dwarf galaxies can form. But “warm” or “hot” dark matter, which by definition moves faster, cannot coalesce so easily. In fact, hot particles wouldn’t be able to form mini-halos at all. So the sheer existence of these small galaxies is a sign that warm dark matter is likely not at play. Read More ›

What, the “single best idea anyone ever had” (philosopher Daniel Dennett on Darwin ) is now comparable to gravity? Experimental physicist Rob Sheldon would take issue with that. Yes, a psychologist seems to think Darwinian natural selection is indeed a force of nature like gravity: Natural selection, one of the fundamental processes of evolution, has something in common with gravity: A public relations problem. At one level of analysis, natural selection, like gravity, looks like a chump. When you’re looking up close at the tiny bits of stuff that go into making humans—the sequences of DNA that constitute the human genome—and how they came to be arranged in the manner that they are, natural selection doesn’t seem to have done Read More ›

Hmmm. We don’t often see serious skepticism of Cool ideas like string theory except from brave souls like Sabine Hossenfelder.  With luck, if this pans out to be a serious discussion, it will begin a trend. Note: Some of us would be okay with “Why String Theory Is Right,” provided it is a response to skepticism taken seriously and the theory is treated as a theory with serious problems—not a sort of foregone conclusion, upholding a multiverse. Hat tip: RealClearScience See also:  Sabine Hossenfelder: Black holes do not behave as string theorists say they should “Perhaps physics has slipped into a post-empirical era…” (from a review of Hossenfelder’s book at Physics World) Post-modern physics: String theory gets over the need for evidence and Read More ›

According to a new paper, white holes, the theoretical opposite of black holes, may account for dark matter, and may even predate the universe. They may even, according to Carlo Rovelli, explain the direction of time: A black hole is one prediction of Einstein’s theory of general relativity. Another is known as a white hole, which is like a black hole in reverse: Whereas nothing can escape from a black hole’s event horizon, nothing can enter a white hole’s event horizon. … In the 2014 study, Rovelli and his team suggested that, once a black hole evaporated to a degree where it could not shrink any further because space-time could not be squeezed into anything smaller, the dying black hole Read More ›