Sunday, December 11, 2016

Listening for a black hole interior

Nature mag reports:
It was hailed as an elegant confirmation of Einstein’s general theory of relativity — but ironically the discovery of gravitational waves earlier this year could herald the first evidence that the theory breaks down at the edge of black holes. Physicists have analysed the publicly released data from the Laser Interferometer Gravitational-Wave Observatory (LIGO), and claim to have found “echoes” of the waves that seem to contradict general relativity’s predictions1.

The echoes could yet disappear with more data. If they persist, the finding would be extraordinary. Physicists have predicted that Einstein’s hugely successful theory could break down in extreme scenarios, such as at the centre of black holes. The echoes would indicate the even more dramatic possibility that relativity fails at the black hole’s edge, far from its core.
This is badly confused. If they are really black holes, then we can only observe what is outside the edge (aka Schwarzschild radius or horizon). No LIGO data can possibly distinguish what is just inside the edge with what is at the center.

Lubos Motl just got finished praising one of the coauthors for winning a big prize, but stops short of saying that he is actually right about something:
That controversial Polchinski et al. paper on the firewalls (AMPS) shows that they are experts in quantum gravity and quantum information but because the assumptions and conclusions are wrong, it's obvious that such a paper can't be said to have a million or multimillion-dollar value from a physics viewpoint. You simply shouldn't be getting physics awards for physically incorrect claims. The whole point of science and physics is to find correct insights about Nature, not just to show that you have mastered some tools and you can design clever, but ultimately irrelevant, arguments that derive incorrect conclusions from invalid assumptions.
This is funny. LuMo is very impressed with the string theorists like Polchinski who do a lot of fancy theorizing about extra dimensions or Planck lengths or black hole interior entropy, but if they apply it to real-world data, then he is honest enuf to call BS.

1 comment:

  1. Roger,
    The two orbiting black holes of LIGO's claim are pretty much bullshit. Think of what the angular velocity of two orbiting block holes would have to be? Is anyone going to seriously say they could orbit each other fast enough to not just collide? Even if they were orbiting each other at the speed of light, which is clearly ridiculous, how would they avoid collision? Considering how massive a black hole would have to be at minimum, and how many times the mass of our sun LIGO claims these black holes to be, are they actually proposing that such masses could move at such angular speeds necessary to maintain their mutual orbit? I was given the impression that even light speed is not a suitable escape velocity for the theoretical black hole, which I don't even believe exists due to their dependence upon the hypostatization of a physical point, which is a pure abstraction. You can no more assign mass to a point than you can a line, or an angle. Sizeless objects can not carry mass or density except in fiction, this was in fact the entire reason String Theory was invented, because a point does not have the degrees of freedom they were trying to assign to it.