# Deepest sound in the universe - so far



## Brian G Turner (Sep 13, 2003)

http://www.nature.com/nsu/030908/030908-14.html

*Black hole makes deepest-ever note*

An immense black hole 250 million light years away is blowing the lowest B flat ever heard.

It sits at the hub of a giant galaxy called NGC 1275, in the Perseus cluster of galaxies. The satellite-borne Chandra X-ray Observatory has spotted ripples in the gas dispersed throughout the cluster.

These ripples of high- and low-density gas are like sound waves in air. But their frequency is far lower than the deepest sound audible to the human ear. A piano capable of producing the note would have 57 octaves below middle C and would be more than 15 metres long.

The sound waves carry immense amounts of energy away from the black hole, heating up the surrounding gas. Researchers suspected that the gas in clusters such as Perseus must be kept warm, but they did not know how.

The booming black hole also stifles star formation. Without the injection of acoustic energy, the gas would cool, reducing its pressure and allowing it to sink into the cluster's centre. This increase in gas density would trigger its collapse and break-up into blobs that would become new stars.

Chandra detects X-rays emitted by hot gas around NGC 1275. Previously the satellite revealed that there are two vast bubbles in this gas, apparently emanating from the galaxy's massive central black hole.

The black hole is gobbling up gas and dust. This becomes immensely heated, and shoots back out as two hot jets in opposite directions from the vortex-like heart of the galaxy. These jets blow out the two bubbles.

The ripples around the bubbles suggest that their growth excites sound waves in the gas, say discoverers Andy Fabian of the University of Cambridge, UK, and colleagues. The distance between successive peaks in the ripples - the wavelength of the sound waves - is about 36,000 light years.

The researchers calculate that the sound waves' heating effect could balance the steady cooling of the gas. Each bubble would have to be blown continuously for around ten million years before detaching from the galaxy core and moving through the gas.


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## mac1 (Sep 14, 2003)

> The distance between successive peaks in the ripples - the wavelength of the sound waves - is about 36,000 light years.


Good God! That bass alone must be capable of shattering planets!


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## littlemissattitude (Sep 14, 2003)

Figures that it would be a B flat.  Back in the day, when I was in elementary school and played the clarinet in the school band (I wanted to play drums, but my parents wouldn't have any of that), I hated B flats - they were particularly hard for me to play without squeaking for some reason.


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## mac1 (Sep 14, 2003)

Aren't clarinets tuned to a B flat too. Or is that just a "B flat clarinet", that is the standard isn't it?


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## Brian G Turner (Sep 14, 2003)

Sound waves in space are a highly under-rated and extremely fascinating phenomena.  They've been found to be especially important in the structure of stars. The idea of a musical universe is incredibly appealing - even if they sound like *littlemissattitude* squeaking on a clarinet.


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## littlemissattitude (Sep 14, 2003)

Bigmacscanlan said:
			
		

> Aren't clarinets tuned to a B flat too. Or is that just a "B flat clarinet", that is the standard isn't it?


It's been a long time.  I know mine was a B flat clarinet, but that didn't seem to help much.  There is at least one other clarinet, the bass clarinet.  Other than that, I've just pretty much blocked all knowledge of the instrument out of my mind.
	

	
	
		
		

		
		
	


	




  I would probably have liked it more if it was a more versatile instrument.  At the time, I was all about rock 'n roll, and there isn't much call for clarinets in that musical genre.  Fortunately, my musical tastes have widened considerably since then.


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## littlemissattitude (Sep 14, 2003)

I said:
			
		

> Sound waves in space are a highly under-rated and extremely fascinating phenomena.  They've been found to be especially important in the structure of stars. The idea of a musical universe is incredibly appealing - even if they sound like *littlemissattitude* squeaking on a clarinet.


You're right, Brian.  I feel like I need to apologize for taking your thread so far afield.  I have to say that I do like the idea of a musical universe - sort of harks back to the times when even scientists talked about "the music of the spheres."


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## Brian G Turner (Sep 14, 2003)

Heh, no need to apologise - it's sincerely nice to humanise these articles.


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