Cosmology 202: Songs of the Cosmos

We primates are visual creatures. Our eyes are so well connected to our brains, by so many miles of intertwined synaptic circuitry, that modern day neurologists consider them an extension of the Cerebrum. It's an evolutionary legacy of our arboreal past. To spot colored fruit from half a mile away and get there before the other guy does, means jumping quickly from limb to limb, high in the canopy where every leap could be the last due to a small miscalculation. It requires reading and processing a staggering information load that leaves the largest supercomputer in the dust. It means sharp eyes, solidly plugged into a big brain. And, after fifty-million years of ruthless selection, it's not surprising the survivors possess high resolution, stereoscopic color-vision, and precise depth perception.

But the most astounding revelations in cosmology since Hubble would come from a new technology beyond sight. And through that venue mankind would enjoy the ancient siren songs of the Universe, unheard down the eons, for the first time. Including the celestial hymn of Creation itself, carried on the gossamer wings of invisible light.

It's worth noting that although Edwin Hubble laid the first cornerstone for the Big Bang using observational data gleaned from the Mount Wilson Observatory, he was almost beat by the most unassuming of people over a decade earlier. An eccentric genius, the archetypical absent minded professor, came within a hair's breadth of deducing the Hubble Redshift without ever looking through a telescope. In what he later called "the greatest mistake of my life", Albert Einstein tweaked his mathematics until he no longer needed his Cosmological Constant. In an odd way, it's almost a relief that he missed it imho. It would have been too weird, downright freaky, if he had deduced the Big Bang from General Relativity, in 1917, without ever leaving his house, much less looking at the universe itself!

Theoretical Physics would have it's day though. The second major piece of evidence supporting the Big Bang would flow from the esoteric equations of atomic physics-in the shadow of the Hydrogen Bomb. The observed ratios of Hydrogen, Helium, Lithium, and their associated isotopes throughout the Cosmos, would turn out to be precisely what Big Bang Nucleosynthesis should produce. The final piece of convincing evidence would come from neither pure mind nor telescopic eye. It would come from a defunct radio antenna which looked for all the world like a cross between a cheap UFO prop and a deformed, rusting boxcar.

As self-centered, aggrandizing hominids, we expect Mother Nature to accommodate our sense of sight and offer up her most splendid secrets for our immediate visual gratification. But there is far more to light than the colors we can see. The optical wavelengths, what we observe when we produce a rainbow spectrum, are but a tiny slice of a big picture. The scope of the entire electromagnetic spectrum is invisible to us. It includes radio waves, microwaves, infrared, ultraviolet, x-rays, and gamma rays; and it is immense compared to the tiny sliver of visible light we can detect unaided.

So, almost from the start of commercial and military applications of radio, astronomers have been pointing all kinds of antenna skyward. From receivers made of wire monstrosities strewn over poles, to spidery networks of aluminum, all the way to the more modern parabolic dishes, these devices have been straining to the heavens to see what they can see. Or rather to hear what we can hear. And what we've heard is both eerie and beautiful. It is the Music of the Cosmos scored with invisible light. Here's a tiny sample:

"Jovian Whistlers"-Jupiter's Magnetosphere: Sprites, Jets, and Lightning 361 KB

"Solar Blowout" MP-3 -Onset of a Solar Flare recorded by Voyager Spacecraft 75 KB

"Traffic Jam"-Neutron Star Cluster in 47 Tucanae. There are dozens of pulsars moving and resonating together within this Globular Cluster. Most with a rotational period in the 25 millisecond range: These neutron stars are spinning in the neighborhood of 40 times per second. The individual tones produced by the pulsars, some of which may be neutron star binaries orbiting each at appreciable fractions of the speed of light, alternately interfere with and amplify one another causing chaotic shifts in the tones: This is the audio equivalent of optical scintillation AKA sparkling. 843 KB and worth it!

"Cosmic Snowflakes" MP3 -Gamma Ray Burster, source unknown

As the resolving power of radio and high energy astronomy improved, it became possible to also translate the invisible wavelength data into optical images. All the better for our primate preferences for visual data.

X-ray Image of suspected Black Hole Cygnus X-3

X-ray Image of Quasar 3C273 in Virgo (Enlarge). Note the jet pointing to 5:00 O'clock. Hot material is being ejected, as if from a gigantic electromagnetic particle accelerator. Cosmologists theorize it's coming from the magnetosphere surrounding a supermassive black hole at the center of the object of perhaps one billion Solar Masses.

Radio data superposed over optical image of Centaurus A. The band of dark material bisecting the spherical body is thought to be a smaller, spiral galaxy seen on edge, crashing into the larger one. Again, the large radio "lobes" in false color are thought to represent hot plasma being ejected magnetically from a hypermassive black hole in the center of the Giant Galaxy. BTW-those streamers are moving at thousands of miles per second and are roughly one-million light years long. Ten times the diameter of our Milky Way Galaxy!

Back in the late fifties however, our burgeoning radio astronomers along with their more traditional optical colleagues, are looking for the earliest signal of all. The Prime Event. The residual glow of the Big Bang. They're not precisely sure at first where in the electromagnetic spectrum to look. The light from the Big Bang should be drastically redshifted. And the signal would be faint; it had after all traveled billions of light years! So they needed to know as closely as they could what band to tune their most sensitive equipment onto. Or at least what range of bands.

Recall that the further you look in space, the further you're looking back in time. So if the Big Bang was really big, we'd expect to be able to look out at an empty region of space and see it. But because of the Hubble Redshift Effect, the further away you're looking in space, the more redshifted the light would be from whatever distant object you're observing. And the Big Bang is as distant as it gets!

An awful lot of brain power went into calculating exactly how much the light would be redshifted. After all the hairy equations were worked out using electromagnetic field theory and tensor calculus, some truly horrifying mathematics which includes multiple vector integrals and Laplace Transforms, the best answers seemed to converge in the ultra short-wave radio region. The light should be redshifted all the way from the visual spectrum, through the infrared, and wind up in the microwave part of the spectrum. Problem: The short-wave to microwave region of the spectrum represents thousands of times the range of its visual counterpart. That meant there were millions of possible bands to look at in the suspect region for an extraordinarily weak signal. A radio needle in a haystack of white noise. It promised to be a long, tedious, search.

Arno Penzias and Robert Wilson in front of the now famous Bell Labs antenna

Science often moves in rather unpredictable ways. But this story is one of the most serendipitous on record considering the end result. Arno Penzias and Robert Wilson, two researchers for Bell Labs, were playing around with an old microwave antenna (above) which had been used to bounce microwave signals off early balloon-born reflector platforms, such as Echo 1. But once the first commercial communication satellite series, the Telstars, were in orbit, the antenna for the balloon project was open to pure research.

Wilson didn't even accept the Big Bang, he held to an alternative called The Steady State Theory. In this view first advocated in its modern form in 1948, the universe was more or less static and infinite. Both researchers understood their defunct communications antenna would be a good receiver of microwaves, and set about to tune it up and tweak it down, to see if the antenna could collect useful data on stellar objects of various types. But right from the get go they had some minor interference coming from inside the antenna. It was picking up a microwave signal no matter where they pointed it. They chased out a flock of Pigeons that had turned the antenna into a home, they cleaned layers of bird droppings out, no luck. They tried hosing it out with water, thought about raccoons or rats, and put in pesticides. It didn't work, the aberration was still there.

In frustration they started looking for other explanations in the electronics or external radio traffic that might be interfering. And about then Robert Dricke of Princeton, who had been looking for the Big Bang afterglow for quite some time, heard about their problems. I have to give Dricke credit for being a classy fellow. He graciously confirmed their data and then quietly stood aside as Penzias and Wilson received credit for the biggest discovery since Hubble. He was excited I'm sure. But he wouldn't be human if he hadn't felt like shooting himself in the head when he realized the two Bell Labs scientists had stumbled onto the prize he had sought for years. Penzias and Wilson had had just the right kind of antenna it turned out, to pick up just the right bandwidth as it happens, to tune in the elusive Microwave Background Signal from the Big Bang.

Strangely, so did Dricke, he just didn't know it. So did fifty-million people by 1960, and odds are you also have a receiver in your home which can pick up the Big Bang Background Glow. Take an old TV, one that's not hooked into cable already, the kind with a rabbit ears antenna. Turn it on and pick any UHF Channel which has no picture, only gray snow on the screen. Some of that snow you're seeing there is coming from the Big Bang ...

Anyway, unlike Hubble's observation, Penzias and Wilson's discovery fell within the realm of physics, and they did receive the Nobel Prize!

Take a moment and listen to a short clip of the sound of Creation: MP3-The Cosmic Microwave Background Radiation 40 KB. Doesn't sound that impressive compared to the Cosmic Music above eh? But that static hum is the light from the Big Bang, Doppler shifted into the microwave wavelength. That sound is our Cosmic Genesis.

Except ... there were still more questions-aren't there always in science? If the Big Bang had proceeded as models suggested and the data seemed to confirm, it should have been perfectly uniform. But if so, there would be no density fluctuations to trigger star formation. The universe would have become a homogeneous mist of featureless Hydrogen, Helium, and a trace of heavier gases. No stars means no galaxies, no heavy elements, and no planets: That means no 'us' along with every thing else we can see in the sky.

The solution to how the Big Bang managed to be just 'lumpy' enough to produce galaxies and stars would lead cosmologists to realize there hadn't been a Big Bang at all: There had been two!

That story next time my fellow cosmonauts.