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back to article Supercomputer vid proves NASA black-hole ring sniffers were RIGHT

Stellar-mass black holes produce their highest-energy light from the turbulent froth of their gas corona, boffins have discovered with the help of a massive amount of supercomputing power. Astronomers from NASA, Johns Hopkins University and the Rochester Institute of Technology used 960 of the Ranger supercomputer's nearly 63, …

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Alert

The study was based on a non-rotating black hole

Is that even possible?

Why on earth(or in space for that matter) would you assume that the black hole was not rotating? there are infinite positive spin speeds and an equally infinite number of negative spin speeds so why choose the one zero state?

Would you always bet on green at roulette?

It's the same reason why a straight line is so unnatural, there are an infinite number of curves either side. (try walking unaided in a straight line whilst blindfolded, its not possible.)

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Boffin

Re: Why would you assume that the black hole was not rotating?

Because it makes the math easier.

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Re: The study was based on a non-rotating black hole

Why on earth(or in space for that matter) would you assume that the black hole was not rotating?

To ensure that the model works before applying it to the more complex but admittedly more common problem of a rotating black hole. As my mom used to say, "better to waste a little supercomputer time on an untested model now, than to waste a lot on a still-untested model later" -- or something to that effect.

FTA: ... the models are now being extended to spinning ones.

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Re: The study was based on a non-rotating black hole

fair enough.

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Anonymous Coward

So we can't produce a computer model which can accurately tell us how the gas particles around our own planet work, but we can produce one which tells us how gas particles around a black hole works... really?

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I guess if there was an event horizon around the planet, within which we basically don't care about what happens because no information is going to leak out of it, then that might make the maths a bit easier than working with a planet full of geological and biological features.

Of course if our planet had an event horizon around it, we'd probably not be in a condition to care about how black holes work.

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Headmaster

Well, the surface of a black hole is a lot simpler to model. No seas. No mountains. No clouds. You do know that was a model of a generic (non-rotating) black hole? That's like saying "we can model some turbulence on a planet" and the difference of "we can model the turbulence perfectly of this specific planet". Massive difference.

I can model the rate of fuel use in your car, but damned if I can predict when you will crash into a tree...

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It's called chaos, or sensitivity to initial conditions. And also, you are comparing chalk to cheese. The black hole model is attempting to model possible behaviour of gas (plasma, surely!) in that environment, and to deduce some average properties such as its temperature. Weather forecasting is an attempt to predict exactly what state the atmoshere will be in tomorrow or next week, given observations of what state it's in today. A black hole type model simply tells you that it's possible that somewhere on the planet you will find a square mile where the air temperature is 40C and the humidity is high. And that nowhere will you find such a square mile where the temperature is 80C.

The weather forecast model is chaotic, or sensitive. You can't measure the atmosphere's current state with complete accuracy. The measurement errors grow with simulated time, to a greater or lesser extent, until the model is wholly erroneous when compared to the later reality. (It still represents possible weather, just not the correct realisation thereof). On the bright side, your forecast for a week out is useful maybe two times in three, and that for two weeks out is a waste of computer time. In the worst case, the not-quite-hurricane that is going to devastate northern France in six hours' time does a sudden right-angled turn and devastates Southern England instead. (Michael Fish, you are forgiven).

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how old is the data? The Ranger supercomputer was decommissioned months ago. My son will be a freshman at University of Texas in the fall. During our campus tour, we got to see the Ranger

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In the subtitle

YOu misspelled 'beeellllion'.

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