Tag: cosmology

Dark Matter Evidence?

While dark matter doesn’t shine or fraternize with known particles, in the right sort of collision these particles could annihilate in a shower of familiar matter and antimatter that would then go out with a puff of gamma rays. A measurement of these offshoots would represent the first evidence of dark matter that wasn’t exclusively gravitational in nature. Yet dark matter wasn’t the only thing that could be generating the excess gamma rays. They could shine from cosmic lighthouses known as millisecond pulsars — magnetically charged neutron stars that make 1000 turns each second. A group of undiscovered pulsars too dim to be picked out individually could be bathing the center of the galaxy in extra gamma rays. Experts express optimism that with these inputs, the current modeling wars could settle down in a matter of years. And now that the gamma ray glow is back on the table, hopes for dark matter look somewhat brighter. “If the galactic center excess is back in the game, potentially we are seeing the first signal of dark matter.”

Scale can weigh a proton

Ricci’s sensor can achieve ~1% accuracy. 1 goal for such precise sensors is to create high-resolution images of individual proteins and other molecules. Bachtold is developing similar sensors made of carbon nanotubes. You could place a single molecule in a magnetic field, which rotates the molecule’s constituent atoms. Because distinct elements rotate at different rates, a nearby force sensor could detect the rate of rotation of the atoms to identify them.

88 OOM Dark Matter Search

physicist Davide D’Angelo and geomicrobiologist Jennifer Macalady travel to Laboratori Nazionali del Gran Sasso to see one of the latest efforts to detect dark matter, the SABRE detector. As with the search for neutrinos, looking for dark matter needs to happen under conditions of “cosmic silence” — in this case, beneath a mountain in Italy. D’Angelo, who is a collaborator on the project, likens the search to “hunting ghosts”.

2020-11-24:

the search spans 10e-21 eV to 10e67 eV, 88 orders of magnitude. perhaps the broadest search ever? The lightest that dark matter could possibly be is about one-thousandth of a trillionth of a trillionth of the electron’s mass — which would result in a particle that’s like an extremely low-energy wave, with a wavelength the size of a small galaxy. Lighter (and therefore longer) entities would be too diffuse to explain why galaxies stick together. The heaviest is a black hole of 30 solar masses.

Is Physical Law an Alien Intelligence?

Or to take this a step further, perhaps the behavior of normal cosmic matter that we attribute to dark matter is brought on by something else altogether: a living state that manipulates luminous matter for its own purposes. Consider that at present we have neither identified the dark-matter particles nor come up with a compelling alternative to our laws of physics that would account for the behavior of galaxies and clusters of galaxies. Would an explanation in terms of life be any less plausible than a failure of established laws?

Complex Dark Matter

Another possibility is this 80% of the universe is also complex. Maybe there’s something interesting going on in what’s called the dark sector. We know that whatever ties us to the dark matter is pretty weak or else we would have already seen it. This observation has led to the belief that all the interactions that could be going on with dark matter are weak. But there’s another possibility: When dark matter particles see themselves, there are complex and potentially very strong interactions. There even could be dark atoms and dark photons.

Cyclic universe

Is Our Universe a One-Off Fluke, or an Endless Cycle?

If we throw out inflation theory, what other explanations do we have?

It’s possible that what we think of as the “bang” that started everything was really just another bounce—a transition from a preexisting phase of contraction into one of rapid expansion. With that idea, there’s a whole new domain of time, before the bounce, before the bang, with which you can introduce processes that would naturally smooth and flatten the universe. The contraction would be very gentle and slow compared to the very rapid inflationary expansion, but it would still go at a non-uniform rate. This would translate into fluctuations of temperature and density after the bounce consistent with the fluctuations we see in the cosmic microwave background. This leads to a picture of a cyclical universe. Could there have been a series of bounces in the past? It’s a natural possibility. With each bounce, there’s always going to be this smoothing, flattening process that ends up erasing information, or spreading out information so thinly from what preceded it, that there is almost no trace of it in the universe that you can directly find. The way you get around the problem of beginning is that there is no beginning. It was always there doing this, forever in the past and forever in the future.