# BOOM in B flat please

## Main Question or Discussion Point

Astronomers using NASA's Chandra X-ray Observatory have found, for the first time, sound waves from a supermassive black hole. The "note" is the deepest ever detected from any object in our Universe. The tremendous amounts of energy carried by these sound waves may solve a longstanding problem in astrophysics.

Very interesting.

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I was reading the article looking
for the frequency of this "sound".
How long does one cycle take? Any
explain how they pegged that very
irregular looking wave as a B-
flat?

thed
Originally posted by zoobyshoe
I was reading the article looking
for the frequency of this "sound".
How long does one cycle take? Any
explain how they pegged that very
irregular looking wave as a B-
flat?
More here, http://chandra.harvard.edu/photo/2003/perseus/. Where they say the central 'cavities' are 50 thousand light years wide. So the waves must be thousands of light years peak to peak. At that long a wavelength, does it matter what note it is.

Originally posted by thed
So the waves must be thousands of light years peak to peak. At that long a wavelength, does it matter what note it is.
Not to me. Apparently it matters
to them because they give it the
unbelievably specific designation
of a B-flat. I'm curious as to
how they could say it is any specific note.

thed
Originally posted by zoobyshoe I'm curious as to how they could say it is any specific note.
I've had an idea about this. Differences in octaves are logarithmic. Though the difference between B and Bb is small, it is magnified by 57 orders of magnitude. Spread over that large a difference the wavelengths will be, hand waving, hundreds of light years apart. Large enough to put a putative tone of Bb on this wave.

Tell you what, let's call it A# instead.

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Originally posted by thed Tell you what, let's call it A# instead.
Yes, but that's going to put it
into a different key.

marcus
Gold Member
Dearly Missed
Originally posted by zoobyshoe
Yes, but that's going to put it
into a different key.
LOL

marcus
Gold Member
Dearly Missed
What pitch is sunlight?

Originally posted by thed

Tell you what, let's call it A# instead.
IIRC the average photon in sunlight is 1 eevee

that is an infrared energy, visible photons have above average energies

1 eevee translates into 2.4 E14 herz

so how many octaves above middle C is sunlight?

Basically it just means taking log (base 2) of E12
because sunlight is E12 higher frequency than middle C.
and an octave is a jump by a factor of 2

Hurkyl
Staff Emeritus
Gold Member
Going down a semitone represents a 6% increase in wavelength... I don't know what the relative error bars are on their measurements, but 6% is a sizable difference.

marcus
Gold Member
Dearly Missed
Originally posted by Hurkyl
Going down a semitone represents a 6% increase in wavelength... I don't know what the relative error bars are on their measurements, but 6% is a sizable difference.
Amen to that, and you can see where the 6 percent comes from if your calculator will take the twefth root of two

21/12 = 1.0595

A piano tuner might use 0.0595 but call it six percent so as not to put too fine a point on it.

I took the log-base-two of 1012 (since it was clear nobody else would except maybe Hurkyl!) and got 40

So I conclude that typical sunlight frequency is 40 octaves above middle C.

If those astronomers can say that their black hole burp
is 57 octaves below middle C, then I can point out the window
and say the sunlight is 40 octaves above. Or?

Or you could say:

We hear the Sun's soprano
with our eyes,

But the Black Hole's bass...

And I couldn't think of a
finish for that. Dip your
quills and finish this pome.

Hurkyl
Staff Emeritus
Gold Member
Well, they were talking about sound waves, not light waves...

marcus
Gold Member
Dearly Missed
both waves though
illustrating general idea of frequency

Originally posted by zoobyshoe
Or you could say:

We hear the Sun's soprano
with our eyes---
The Black Hole's bass
sends ripples through the skies.

Marcus gave me the right push.
This is where I had wanted to
go:

We hear the Sun's soprano
with our eyes,
But Black Hole's bass carves
ripples in the skies,
A roar so deep no human ear
will know
A single beat of Black Hole's
demon crow

Iambic pentameter. Two rimes. It's
a couple 'o cosmological couplets.

hypnagogue
Staff Emeritus
Gold Member
Awesome, zoobyshoe. Take a bow.

Thank you, Hyp, for enjoying my
scribbles.

hypnagogue
Staff Emeritus
Gold Member
The scribbles of this pauper be
To kings a chamber symphony

That's nice. What's that from?

hypnagogue
Staff Emeritus
Gold Member
Spontaneous random electrochemical processes in my brain. Or something like that.

That was very fast. You
must have been channeling some
departed poet or else you're in the habit of writing alot yourself
so that you're never far from
Dylan Thomas' "Well of Poetry"
where he went every day to pull
up two lines.

hypnagogue
Staff Emeritus
Gold Member
I write a bit, yeah. For some reason 8 syllable rhyming iambic pentameter couplets in particular plop out of my head very readily (not sarcastic).

I think it's due to my brain wave frequencies cohering with faint but non-negligible B-flat black hole notes from the center of the galaxy. (How's that for not getting too far off topic? No? Can't say I didn't try. )

Well Done zoobyshoe. So good. You should be a poet not a scientist.

zoobyshoe said:
Yes, but that's going to put it
into a different key.
Can be easier to play in a different key sometimes. LOL. I should know. People complain to my about my music and say 'That is too high for me too play. I am a Horn player not a soprano player'. And I just say 'Thanks for telling me (but you do know that practise helps)'. So then trasnposition all the way. LOL