Sounds in Space: Silencing Misconceptions

Yahoo! News ^ | Monday, September 22, 2003 | By Robert Roy Britt, Space.com

[Aracelis]

perhaps scratchings on a rock thanks to an inquisitive T. Rex?

ROFL!

As to your inquiry, let's ask the FR resident brainiacs (my background is in carbonate geochemistry). Gentlemen, would you have any comments on Post 19? Thanks!

[Aracelis]

Aw, you beat me to it. :^)

[RightWhale]

It would help if English had a non-gender specific singular personal pronoun.

It does, of course, in 1st and in 2nd person singular. But, our English teachers told us to stop using 2nd person all the time, and we still haven't progressed to the general [affected] use of the pronomial one in place of the 1st or 2nd person. Using one for the 3rd person is nonsense. The astronaut example could be phrased in the pronomial one. One could remove one's helmet.

[Physicist]

Call me suspicious, but how exactly does one make a measurement of a physical process which occurs once every 19 million years? Is there something in the fossil record,

Yes, in a way. The fossils aren't to be found in Earth's rocks, of course, but in the nebula surrounding the black hole. Per the article:

Every 10 million years, a fresh wave bubbles out of the system.

...

As the pressure peaks travel outward from the cavities around the black hole, collisions occur between atoms in the gas, generating X-rays that reveal a concentric ring pattern. Being a form of light, X-rays can traverse the universe sans any medium, and these are what Chandra detected.

The sound waves rapidly die out, their energy converted to heat. So in essence the B-flat was seen, not heard, from 250 million light-years away.

So there you have it: a series of concentric density waves, spaced at 10-million-year intervals, centered on the black hole.

[RadioAstronomer]

The frequency is about 9.5 million years between wave crests. (It was the B-flat above the middle C. :-)

What they are "seeing" are ripples in the hot gas inside the cluster that the black hole resides in. By measuring these ripples and the effects from them, the sound waves can be calculated.

[RadioAstronomer]

Your explanation was more informative than mine! :-)

[KayEyeDoubleDee]

So, I assume it is trivial to observe these concentric rings of X-rays, spaced at intervals of 10 million light years?

And then measure their frequency with such accuracy to extrapolate the B-flat which caused them?

[MetalHeadConservative35]

now THAT is some low end..if only i could get that kinda low end outta my amp ehehehehe

[RadioAstronomer]

So, I assume it is trivial to observe these concentric rings of X-rays, spaced at intervals of 10 million light years?

Remember the speed of sound is far less than the speed of light. The size of the ripples are about 30,000 light-years.

[KayEyeDoubleDee]

Btw, thanks for not rudely pointing out that I obviously didn't read the whole article. On a related note, I'm glad that the mail that I meant to send wasn't (mainly b/c Linux/KDE desktop apps fundamentally suck).

And on a unrelated note, I have a question about simulataneous events in relativistic frames of reference. A few years ago, we talked about the seemingly paradoxical nature of the old "ladder speeding through a barn" problem. And how the differing sequence of events in the two frames of reference resolve the question of what happens (or is seen to happen) when the ladder is (is not) fully within the barn, and the barn doors are closed. Namely, in the barn's frame of reference, the doors may be closed simultaneously around the ladder (enclosing it) and the ladder is seen to bursts through the far door, while in the ladder's frame of refernence, the door (not yet behind it) is still open while the ladder blows throught the closed door ahead of it, therefore never being enclosed by the barn. Here's my question: What if some third event is contingent on two events (say the closing of the two doors) occuring simultaneously. In the barn's frame of reference, this third event would occur, while in the ladder's frame of reference it would not. My suspicion is that any experiment which I could set up to point out this paradox would require some kind of "spooky action at a distance." What do you think?

[KayEyeDoubleDee]

Remember the speed of sound is far less than the speed of light. The size of the ripples are about 30,000 light-years.

It seems to me that if some process occurs once every 10 million years, then a byproduct travelling at the speed of light will be 10 million light years away at the next occurence.

[RadioAstronomer]

It seems to me that if some process occurs once every 10 million years, then a byproduct travelling at the speed of light will be 10 million light years away at the next occurence.

Indeed if the sound waves were traveling at c, they would be. The waves heat up the gas, which then emit X-rays.

[KayEyeDoubleDee]

Indeed if the sound waves were traveling at c, they would be. The waves heat up the gas, which then emit X-rays.

But it is the concentric rings of X-rays which is actually observed, right? Wouldn't these rings grow to be 10 million light years in diameter between cycles?

[KayEyeDoubleDee]

I think I get it. The sound waves are producing an "image", which is seen via the Xray emissions.

[RadioAstronomer]

I think I get it. The sound waves are producing an "image", which is seen via the Xray emissions.

Yes. :-)

[KayEyeDoubleDee]

Here's my question: What if some third event is contingent on two events (say the closing of the two doors) occuring simultaneously

Nevermind, I think I had a revelation in the shower just now (or the retrieval of a suppressed memory from undergraduate days) that simultaneity in time, without consideration of location, is meaningless.

[KayEyeDoubleDee]

Doh! More or less the same way that we see ripples in a pond.

[Aracelis]

Thanks, fellas. :^)

[giotto]

LOL! Of course--now it makes sense.

[JoeSchem]

I knew a male english professor cum bureaucrat who would always do that, and make a big point of casualness when he did. He worked for a woman. He was also privately alleged by several women who worked under and around him to be a serial harasser to the point of being a borderline rapist.

Shades of Bill Clinton, whose 'boss' was the American feminist movement. Seems to be a common theme, that when a guy goes overboard with the window dressing and trappings and affectations of feminism, you know he's a real lout with women in his personal life.