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Friday, December 23, 2011

Music of the Universe

In seventh grade, my science teacher told us,

"There's no sound in space." 

Perhaps you were told this too? After all, space is a vacuum, and sound requires a medium to travel through, right?

Like so many of our cherished childhood "facts," the answer is yes...and no. I made this delightfully unsettling discovery this morning, while reading "For the Love of Physics" by MIT physics professor Walter Lewin (this book deserves a spot in the literary vesicle). It turns out that space is not a perfect vacuum (though a much better vacuum than any vacuum we could make on "perfection" relative?):  Matter (mostly plasma) exists in space, and  therefore pressure waves, and thus sound, can be produced and propagated. There's actually lots of sound in space! The catch is, our ears can't hear those frequencies. So yes, space is a vacuum, but no, it's not a perfect vacuum. And yes, there's sound in space, but no, we can't hear the sound (and if we can't hear the sound, is it a "sound"? It's the age-old question, "If a tree falls in the wood and no one hears it, does it make a sound?"--see related post). 

Disappointing, isn't it? After a promising realization of sound in space, we still won't ever be able to hear the music of the cosmos? 

Once again, the answer is yes...and no. True, "the big bang produced a bass gong sound that now has a wavelength of about 500 million light-years, a frequency of about fifty octaves (a factor of 10^15) below anything our ears can hear" (For the Love of Physics). The good news is that astronomer Mark Whittle has reproduced the sounds of the big bang for us to listen to (small caveat: it's raised in pitch by 50 octaves and compressed in time from 100 million years into 10 seconds)!

Click to listen to the big bang:
Read about big bang acoustics here:

Consider for a moment if the most basic units of the universe were like musical notes--resonant frequencies of unimaginably tiny strings. And these "musical notes" were what produced all our elementary particles (such as the electron). In effect, this is the basic tenet of string theory. And if string theory holds any ground (who knows if it does?), then the universe is a beautiful symphony of sound!

Of course, that depends on what you constitute "beauty" and "music" as. You've heard the "music" of the heavenly spheres. Now it's up to you to decide if that constitutes as music. The answer's probably yes...and no.