Superconductor Sonics

A new experimental sound-source:

… in 1987, a totally unexpected revolution took place: a new family of superconductors based on copper and oxygen smashed all records, taking the highest known superconducting temperatures up to a balmy −150C. BCS theory, which worked so well for simple, elemental superconductors, couldn’t explain the behaviour of these new materials. […] A paper published last week brings us a step closer to understanding how these new superconductors work. Physicists, including my old officemate Paul, used some of the biggest magnetic fields on Earth to try to work out what’s happening inside these materials. In fact, the pulsed magnets used burn through enough energy to melt a tonne of steel every second. […] … the mechanism that underlies this advanced physics apparatus for measuring materials in massive magnets is almost identical to a theremin. …

Audio at the main link.

(Via.)

Underlinings (#57)

Scientists are hard at work of course, trying to detect and understand these phenomena. And they may one day succeed. But their failure to understand the depth of their ignorance until very recently speaks to a problem with the scientific method itself. […] The long climb to scientific supremacy begun by Aristotle in his invention of symbolic logic has in the end taken us to the summit of what turns out to be a very small hill, as we crane our necks upward at a looming, unseeable, unending mountain range. […] Worse, the mountains we cannot see or understand will nevertheless affect us in ways we can’t imagine. It is positively Lovecraftian.

Island Universes

Before we move on to what we don’t know about [cosmological] inflation, there are a few things we do know that are worth mentioning.
1. Inflation isn’t like a ball — which is a classical field — but is rather like a wave that spreads out over time, like a quantum field.
2. This means that, as time goes on and more-and-more space gets created due to inflation, certain regions, probabilistically, are going to be more likely to see inflation come to an end, while others will be more likely to see inflation continue.
3. The regions where inflation ends will give rise to a Big Bang and a Universe like ours, while the regions where it doesn’t will continue to inflate for longer.
4. As time goes on, because of the dynamics of expansion, no two regions where inflation ends will ever interact or collide; the regions where inflation doesn’t end will expand between them, pushing them apart.

(This only gets us to Tegmark Level 1.)

Fake Physics

Some exorbitant multiverse complications:

[Paul] Davies argued that in a multiverse, “‘fake universes’ would be even more likely to vastly outnumber real universes [than in our one universe without a multiverse], so that if we live in multiverse, we would be overwhelmingly more likely to be living in a simulated reality. But that would imply that the laws of physics in our universe are also overwhelmingly more likely to be simulations and therefore cannot be used to conclude that there is a multiverse! So there is an inconsistency at the heart of the multiverse concept.”

Let’s unpack the argument and lay it out. To Davies, “If you take seriously the possibility of a multiverse of all possible universes, including all possible variations, then there would have to be at least some of those universes where sentient civilizations would advance to the point where they would have sufficient computing power to simulate entire fake worlds (like in the ‘Matrix’ movies). Simulated universes are much cheaper to make than the real thing. So once you’ve got civilizations throughout the multiverse that can simulate universes,” Davies stressed, then this is what they will do, and do increasingly.

As a result, “the number of fake universes in a multiverse will proliferate greatly and very soon outnumber real ones.” [Is Our Universe a Fake?]

Fake universes, Davies said, “undermine all the arguments for a multiverse,” because arguments for a multiverse are based on the physics of this universe. “But if ours is a simulated universe, then our laws are simulated, too, which means that the whole of physics is a fake.” And if the whole of physics is a fake, Davies said, then the whole argument for a multiverse collapses. The reason is that while the multiverse argument proceeds from the physics humans have discovered in this universe, people cannot use this argument because it then leads, surprisingly, to the conclusion that this is a fake universe, with fake physics.

Cthelll Vortex

‘Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth’s core surface’, N Gillet, D Jault, C. C. Finlay (Submitted on 29 Feb 2016), abstract:

We report a calculation of time-dependent quasi-geostrophic core flows for 1940-2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely the model errors arising from interactions between unresolved core surface motions and magnetic fields. Temporal correlations of these uncertainties are accounted for. The covariance matrix for the flow coefficients is also obtained recursively from the dispersion of an ensemble of solutions. Maps of the flow at the core surface show, upon a planetary-scale gyre, time-dependent large-scale eddies at mid-latitudes and vigorous azimuthal jets in the equatorial belt. The stationary part of the flow predominates on all the spatial scales that we can resolve. We retrieve torsional waves that explain the length-of-day changes at 4 to 9.5 years periods. These waves may be triggered by the nonlinear interaction between the magnetic field and sub-decadal non-zonal motions within the fluid outer core. Both the zonal and the more energetic non-zonal interannual motions were particularly intense close to the equator (below 10 degrees latitude) between 1995 and 2010. We revise down the amplitude of the decade fluctuations of the planetary scale circulation and find that electromagnetic core-mantle coupling is not the main mechanism for angular momentum exchanges on decadal time scales if mantle conductance is 3 10 8 S or lower.

(Via.)