Tag: cosmology

Antimatter Containment

Antihydrogen does not naturally occur on Earth; physicists first synthesized it in 1995 at CERN. But these particles moved at nearly the speed of light and disappeared in 40 billionths of a second. It would take another 7 years before physicists could produce near-motionless antihydrogen that would not immediately knock into regular matter and annihilate. And it wasn’t until 2010 that they could successfully trap and store antihydrogen. Hangst’s team can now perform experiments for up to 24 hours at a time on the antihydrogen, 12 orders of magnitude in 25 years

Hawking radiation

the hologram within a hologram gives the desired answer to the question of what happens to a 2D black hole’s information. Most experts assume that if the reasoning is correct, it should carry over to higher-dimensional black holes like those in our universe. A common concern, however, is that the authors might be reading too much meaning into this abstract calculation

Cosmological Bootstrap

There’s no “time” variable anywhere in the new bootstrapped equation. Yet it predicts cosmological triangles, rectangles and other shapes of all sizes that tell a sensible story of quantum particles arising and evolving at the beginning of time. This suggests that the temporal version of the cosmological origin story may be an illusion. Time can be seen as an “emergent” dimension, a kind of hologram springing from the universe’s spatial correlations, which themselves seem to come from basic symmetries. The approach has the potential to help explain why time began, and why it might end. “The thing that we’re bootstrapping is time itself.”

Magnetars

For each chunk, the team extracted information about the elemental composition of the gases there, creating a more accurate picture of the supernova remnant’s composition than if they had averaged over the whole. They estimated that the supernovas came from stars between 10 and 20 times the mass of the sun — which means they were less massive than what’s needed to give birth to dynamo-powered magnetars.

Proton Radius

Muon-orbited protons are 0.84 femtometers in radius — 4% smaller than those in regular hydrogen. If the discrepancy was real, meaning protons really shrink in the presence of muons, this would imply unknown physical interactions between protons and muons — a fundamental discovery. 100s of papers speculating about the possibility have been written. After Pohl’s muonic hydrogen result, a team of physicists set out to remeasure the proton in regular, “electronic” hydrogen. Finally, the results are in: The proton’s radius is 0.833 femtometers, give or take 0.01, a measurement exactly consistent with Pohl’s value. Both measurements are more precise than earlier attempts, and they suggest that the proton does not change size depending on context; rather, the old measurements using electronic hydrogen were wrong.

Don’t Fear The Simulators

don’t worry if we happen to live in a simulation.

That means it knows these experiments are going to happen. If it cares about the results, it can fake them. Assuming for some reason that it made a mistake in designing the cosmic background radiation (why are we assuming this, again?), it can correct that mistake now, or cause the experimental apparatus to report the wrong data, or do one of a million other things that would prevent us from learning we are in a simulation. The Times’ argument requires that simulators are so powerful that they can create entire universes, so on-top-of-things that they will know the moment we figure out their game – but also so incompetent that they can’t react to a warning published several years in advance in America’s largest newspaper. There’s another argument for the same conclusion: the premises of the simulation argument suggest this isn’t the simulators’ first rodeo. Each simulator civilization must simulate 1000s or millions of universes. Presumably we’re not the first to think of checking the cosmic background radiation. Do you think the simulators just destroy all of them when they reach radio-wave-technology, and never think about fixing the background radiation mismatch or adding in some fail-safe to make sure the experiments return the wrong results?

Against High Energy Physics

high energy physics thinks that bigger colliders will let them find new particles, but this view is probably wrong.

You could build a circular machine 3x the size of the Large Hadron Collider to collide electrons and positrons; you could upgrade the LHC, or even build a next-generation linear accelerator. Probing higher energies offers the hope of new physics — it could be supersymmetry, it could be something else, I don’t know what. But before exploring higher energies, it makes sense to me to build a muon collider, and to clarify the question of the Higgs first. Here we already have a particle that we want to explore. We may even find signs of new physics by studying the Higgs very precisely. For that we don’t need to go to a 100-kilometer-around tunnel. Think about how many days it takes to walk 100 kilometers! And it all has to be extremely functional, every single piece has to work — it’s a miracle if people succeed in making it work.

Universal Scaling

And this scrambling process happens very early indeed. In their papers this spring, Berges, Gasenzer and their collaborators independently described prescaling for the first time, a period before universal scaling that their papers predicted for nuclear collisions and ultracold atoms, respectively. Prescaling suggests that when a system first evolves from its initial, far-from-equilibrium condition, scaling exponents don’t yet perfectly describe it. The system retains some of its previous structure — remnants of its initial configuration. But as prescaling progresses, the system assumes a more universal form in space and time, essentially obscuring irrelevant information about its own past. If this idea is borne out by future experiments, prescaling may be the nocking of time’s arrow onto the bowstring.

Essay on long-term threats

On BBC Future I have an essay concluding their amazing season on long term thinking where I go really long-term: The greatest long term threats facing humanity. The approach I take there is to look at the question “if we have survived X years into the future, what problems must we have overcome before that?” It is not so much the threats (or frankly, problems – threat seems to imply a bit more active maliciousness than the universe normally brings about) that are interesting as just how radically we need to change or grow in power to meet them. The central paradox of survival is that it requires change, and long-term that means that what survives may be very alien. Not so much a problem for me, but I think many disagree. A solid state civilization powered by black holes in a starless universe close to absolute 0, planning billions of years ahead may sound like a great continuation of us, or something too alien to matter.