Wednesday, May 23, 2018

Giant black hole is cosmic vacuum cleaner

Science popularists used to go around telling ppl that it is a big myth that a black hole can act as a cosmic vacuum cleaner. The Wikipedia List of common misconceptio used to say so.

The NY Times reports:
Astronomers in Australia now say they have found the hungriest heart in all the cosmos. It is a black hole 20 billion times the mass of the sun eating the equivalent of a star every two days.

The black hole is growing so rapidly, said Christian Wolf, of the Australian National University, who led the team that found it in the depths of time, “that it is probably 10,000 times brighter than the galaxy it lives in.” So bright, that it is dazzling our view and we can’t see the galaxy itself. ...

Black holes are a one-way gate to gravitational oblivion, according to Einstein’s theory of general relativity, but they can only swallow so much, depending on their size; the rest of the matter and energy gets splashed out across space, producing the fireworks popularly known as quasars.
Continue reading the main story

The blaze from material swirling around this newly observed drainpipe into eternity — known officially as SMSS J215728.21-360215.1 — is as luminous as 700 trillion suns, according to Dr. Wolf and his collaborators. If it were at the center of our own galaxy, the Milky Way, it would be 10 times brighter than the moon and bathe the Earth in so many X-rays that life would be impossible.
Based on this, I'd say that it is fair to call a black hole a cosmic vacuum cleaner. No space traveler would want to get anywhere near such a thing.

This is also one of the brightest objects in the universe. Not so black, I guess.

NY Times also reports:
It happens every 405,000 years. The Earth’s orbit gradually changes shape from almost circular to slightly elliptical over a period of 202,500 years, and then starts returning to form over the next 202,500 years — like a metronome swinging side to side.

Right now, we are in an almost perfectly circular orbit around the sun, and soon — within some thousands of years, that is — we will start moving toward the elliptical.

This happens because of the Earth’s gravitational interactions with other planets, especially Jupiter and Venus — Jupiter because it is very large, and Venus because it is very near.
Is this settled science? It seems like it could have far-reaching consequences. Maybe life on Earth was only possible because Earth is stabilized by the Moon, Venus, and Jupiter.

Monday, May 21, 2018

Quantum supremacy delayed to attend funerals

Scott Aaronson announces:
a weeklong visit to Google’s quantum computing group in LA. While we mourned tragedies—multiple members of the quantum computing community lost loved ones in recent weeks — it was great to be among so many friends, and great to talk and think for once about actual progress that’s happening in the world, as opposed to people saying mean things on Twitter. Skipping over its plans to build a 49-qubit chip, Google is now going straight for 72 qubits. And we now have some viable things that one can do, or try to do, with such a chip, beyond simply proving quantum supremacy — I’ll say more about that in subsequent posts.
When you are overdue on a high-profile project, the last thing you want to admit is that your goal is unrealizable.

No, a better strategy is to (1) say that you are attending funerals of family members, and (2) raise the stakes, and say that a higher goal can be achieved instead if only managed supplies more time, staff, and money.

Am I being too cynical here? Okay, maybe.

Google and IBM both bragged that they would achieve quantum supremacy in 2017. They said that 50 qubits was the magic threshold. They they dropped back to 49 qubits, a number that seems carefully chosen to allow them to claim the first real quantum computer, but such that they would not have to show the performance that we expect from quantum supremacy.

2017 ended with no new 49-qubit quantum computer, no quantum supremacy, and no explanation for the failed promises.

Okay, maybe they really did have some funerals to attend. Maybe quantum supremacy is really just around the corner.

I don't believe it. They are stringing along with empty promises, as this community has done for 20 years.

I will be watching for any proof that I am wrong. I will post it as soon as it is announced. Then you can all laugh at me.

But if there is still no quantum supremacy in 5 or 10 years, what will you say then?

Monday, May 14, 2018

Beables and brown cows

A new paper starts:
From its earliest days nearly a century ago, quantum mechanics has proven itself to be a tremendously accurate yet intellectually unsatisfying theory to many. Not the least of its problems is that it is a theory about the results of measurements. As John Bell once said in introducing the concept of `beables', it should be possible to say what is rather than merely what is observed.
This paragraph describes how Physics forked into hard science and philosophical beable-babble.

I am a logical positivist. So I have a simple attitude when you start talking about things that cannot be observed, then you as might as well be talking about ghosts. If there is no scientific observational way of saying that you are right or wrong, then it is just opinion, or philosophy, or religion, or some other immaterial belief. It is like you telling me that you like paintings of water lillies. I will not usually even have an opinion as to whether you are right or wrong, because it is not clear that any such opinion makes any sense.

Bohr, Heisenberg, and other creators of quantum mechanics were positivists.

At some point positivism fell out of fashion, and hardly anyone advocates anymore. But this beable stuff has gone nowhere. No good physics has resulted from beable theory.

The paper tells this story:
When I was in graduate school in Scotland, I was told the following parable by my advisors. An economist, a mathematician, and a logician were on a train traveling north. Just after they passed the Scottish border they noticed a single cow standing in a field. The economist remarked, "That cow is brown. All cows in Scotland must be brown." The mathematician replied, "No, one cow in Scotland is brown." The logician quietly but firmly muttered "No, one side of one cow in Scotland is brown." There are many versions of this parable involving a variety of professions and there are any number of lessons to be taken from it. It is usually meant as a dig at one of the particular professions that is included, especially when told by a member of one of the other professions. At the heart of the parable, though, is an open question: how much can we reasonably infer from a given observation?
The author thinks that the mathematician is the most reasonable of the three.

At least cow color can be measurement. Many of the arguments about foundational quantum mechanics involves things that cannot be measured.

Saturday, May 5, 2018

Aaronson discusses whether education is worthless

A new book by radical libertarian economist Bryan Caplan says that public education is a big waste of money, and complexity theorist Scott Aaronson reviews it:
When the US Congress was debating whether to cancel the Superconducting Supercollider, a few condensed-matter physicists famously testified against the project. They thought that $10-$20 billion for a single experiment was excessive, and that they could provide way more societal value with that kind of money were it reallocated to them. We all know what happened: the SSC was cancelled, and of the money that was freed up, 0% — absolutely none of it — went to any of the other research favored by the SSC’s opponents.

If Caplan were to get his way, I fear that the story would be similar. Caplan talks about all the other priorities — from feeding the world’s poor to curing diseases to fixing crumbling infrastructure — that could be funded using the trillions currently wasted on runaway credential signaling. But in any future I can plausibly imagine where the government actually axes education, the savings go to things like enriching the leaders’ cronies and launching vanity wars.

My preferences for American politics have two tiers. In the first tier, I simply want the Democrats to vanquish the Republicans, in every office from president down to dogcatcher, in order to prevent further spiraling into nihilistic quasi-fascism, and to restore the baseline non-horribleness that we know is possible for rich liberal democracies.
No, cost overruns killed the SSC. It was designed and budgeted for a 4cm tube, and they later decided that they needed 5cm, requiring billions of dollars more in superconducting magnets.

The SSC was oversold, but I doubt that Congress realized that. It was supposed to find lots of new physics. The Europeans then went and built the LHC, but all it did was to confirm the Standard Model and measure the Higgs mass.

I am mainly just trying to understand Aaronson's thinking here. He is obviously a typical Jewish leftist intellectual authoritarian here, as he pushes for one-party rule with ample funding for his favorite academic projects.

Does this explain his strange silence about quantum computing? He has been refusing to comment to the press. He has spent much of his life researching the potential for quantum computing, so you'd think that he would be excited by all the current research. Maybe he knows that it is an overhyped dud, but doesn't want to say so because he doesn't want the research money to be diverted into areas of less intellectual interest to him.