In an earlier post I talked about how certain kinds of dark matter might be detectable by the global positioning system (GPS). Part of the reason for that is due to the fact that GPS satellites have extremely precise clocks in them. So precise that the relativistic effects of gravity and relative motion have a measurable effect on the rate at which their clocks tick. This led some readers to ask just how gravity can affect the flow of time. It all has to due with Einstein’s theory of relativity.
Aziz! Light!
After making a successful landing on 67P/C-G, the Philae probe gathered as much data as it could before entering “sleep mode.” It’s not clear at this point whether it will revive again. While the ESA team had hoped Philae would have remained active longer, the lander did complete all of its major data gathering, so we can call this a win. The reason Philae went into sleep mode is that it happened to land in the shadow of a cliff, which meant it wasn’t getting enough exposure to sunlight to keep its batteries charged. Like many spacecraft, Philae is solar powered. It needs light to keep going.
Technicolor Dreams
There’s been some buzz recently about doubts regarding the existence of the Higgs boson. The popular press has picked up on this a bit, leading to claims that it’s similar to the BICEP2 debacle. In this case the comparison is unfounded. There’s been some interesting work, but nothing that merits tracking down Peter Higgs and taking back his Nobel prize.
A Matter of Principle
Imagine taking a bucket of water and spinning it. As you rotate the bucket, the water would fling outward a bit, so that the surface of the water is concave. Compare that to a bucket of water that isn’t spinning, so that the water is flat. If both buckets are perfectly smooth and symmetrical, and the water is perfectly calm, the only difference you would see is that one bucket has concave water and the other has flat. But why are they different?
Sphere of Influence
Suppose you were to flash a light where you are at this moment. The light would speed away from you at about 300,000 kilometers per second, which is known as the speed of light. In general you could point the light in any direction, so flash of light would in general be an expanding sphere of light.
Problematic
Newton’s law of gravity takes a bit of calculus to really wrap your head around it, but the basic relation is very simple. Every pair of masses in the universe experiences a mutual gravitational attraction, each feeling the pull of the other’s gravitational field. The force of attraction is mutual, which leads to some interesting consequences. For example, when you …
Flyby Night
The most likely explanation for the flyby anomaly is some subtle but mundane effect we just haven’t pinned down. But there is always a chance that it is due to something more exotic. The effect is definitely there, so it is worth exploring each time there is a close flyby.
Higgs Goes the Theory
Recently in the news there’s been talk of a new cosmological model known as Higgsogenesis. A paper outlining this model has been recently been published Physical Review Letters. The term Higgsogenesis refers to the first appearance of Higgs particles in the early universe, just as baryogenesis refers to the appearance of baryons (protons and neutrons) in the early moments after the big bang. While baryogenesis is a fairly well understood process, Higgsogenesis is still very hypothetical.
Neutrino Rain
Yesterday I talked about the weirdness of neutrinos, specifically that there three types of neutrinos (known as flavors), and they can oscillate between different flavors due to the quantum fuzziness of their masses. If you go back and read that post, you’ll find its a pretty bizarre model that seems to assume a great deal just to solve what is known as the solar neutrino problem. So how could we possibly know that such a model is correct?