To date, at least 19 galaxies have been discovered that appear to be missing dark matter altogether. What this means, in practice, is that these galaxies are rotating so slowly that no additional matter, beyond their complement of visible baryons, is required to explain their gravitational coherence. Only fast-spinning galaxies need the gravitational attraction of extra matter to hold them together; our traditional understanding of gravity is enough to keep the slow-spinning ones from flying apart.
Spacetime
Soviet Atomic Bombs Help Explain Earth’s Magnetic Field
Here’s an interesting article about the source of Earth’s magnetic field – “Earth’s inner core is doing something weird” by Maya Wei-Haas. Back in the 70s, the Soviets tested some huge atomic bombs. The shockwaves bounced off the Earth’s core and were picked up by geologists in Montana. Recently, scientists revisited the data and have […]
Is Reality Entirely Mental?
Given the infinite divisibility of matter, ought we conclude that the fundamental stuff of reality is mere information? That is, if we were to keep splitting matter into smaller and smaller bits, what else could possibly be down there besides abstract concepts and math? In a recent article in Scientific American, Bernardo Kastrup discusses Max […]