What Does It Mean?

It’s worth taking a pause right now to consider where we’ve come. We started with a brief biography of physics, moving from the earth-centered view of things to a vast universe that might be just one of virtually infinite universes. This view is called the multiverse.  We’ve seen that the Big Bang Theory is currently the predominant theory on how the universe came into being. It is now almost universally (no pun intended) recognized as the accepted theory because it and it alone explains what we observe.

By running the Big Bang backwards we are led to an inescapable conclusion: that everything was all together in one place at one time. That instant in time is the Big Bang itself, the instant when immeasurable energy exploded. Both space and time began at that instant. We’ve speculated on what caused the Big Bang and we’ve run into a knotty problem that occupies physicists today. How do we reconcile General Relativity and String Theory? Is there one unifying theory? This unifying theory is given the name of the Grand Unifying Theory, inelegantly known as GUT. Too bad scientists have fallen prey to the seemingly insatiable desire to create an acronym for everything.  But science is no different than anyone else. We have reduced the Supreme Court of the United States to SCOTUS, which looks an awful lot like scrotum. But I digress.

We have seen that there are three possibilities for why the universe is the way it is. The first is that it is a random event. After the Big Bang there were almost infinite possibilities for how the universe could turn out and it turned out this way. In other words, we won the cosmic lottery; otherwise we wouldn’t be here to ask such questions. The second possibility is that of the 10500 universes that exist in the String Theory-predicted multiverse, the odds are that at least one of them would be like ours, that is, capable of sustaining life. The final possibility is that, given how exquisitely fine-tuned our universe is, it must be the product of intelligent design.

We purposely chose this last postulate because it gives us much more room to let our imaginations run wild as to what form this intelligent design takes, is this a Supreme Being in the classical sense of God, does time exist for God, what was God doing before he created the universe and what is He doing now. Along the way we rejected two other possibilities, one suggested by Isaac Asimov that this universe is the creation of a super-computer created by another civilization; and the String Theory variant of that that we are all simulations in a highly evolved Farmville game being run by a seventh-grader somewhere.

So, where we are is with the proposition that a Supreme Being, God, created this universe. The Big Bang is consistent with Genesis. What does that mean for us?

First of all, it gives real problems to the evolutionists. Evolution takes a similar tack as String Theory. Over time, given so many variants in organisms, we evolved. Evolution has no need for God, just as LaPlace had no need in his theory. But if God created this universe for us, doesn’t it make sense that He also placed animals, plants, microbes and all other forms of life here as well? If evolution is going to stand on the proposition that God isn’t necessary for life to have developed on Earth then it better explain the existence of the universe in the first place.

With the almost certainty of further offending anyone other than a physicist, I’ll close this post with one of my favorite quotations

on science. This is from Ernest Rutherford:   File:Ernest Rutherford cropped.jpg

                       All science is either physics or stamp collecting.

By this he meant that every other science is simply concerned with categorizing information.

What Did the Big Bang Look Like?

As I wrote in an early post, many people are familiar with the basic Big Bang Theory: that the universe was born in a violent explosion.  Beyond that popular conception is hazy, with a lot of people thinking the planets, stars, galaxies, asteroids and everything else popped into being fully formed.

If you had been present at the explosion there wouldn’t have been much to see.  Unimaginable amounts of energy were released.  It was pure chaos, with temperatures far too high to allow the energy to convert to matter (Einstein’s famous E = mc2 , where E stands for energy, m for mass and c for the speed of light shows that energy and matter are interchangeable).  However, within about 300 seconds of the Big Bang the temperature had dropped to where lighter elements like hydrogen and helium could form.  During the next critical minutes nuclei were formed.  Once the universe cooled to about one million degrees C, nuclear fusion stopped.  Matter existed in a state known as plasma.  Most people are familiar with the first three phases, solid, liquid and gas.  Hotter than gas, plasma is a state of matter in which the temperature is so high that atomic nuclei cannot hold onto electrons.  This condition existed until the temperature dropped to about 3,000 C, which took about 300,000 years.  At that point nuclei could hold onto electrons and elements began to form.

One other thing was present at the Big Bang: enormous amounts of light.  Had you been there you wouldn’t have seen anything because light is scattered by plasma, just as it is scattered by water droplets in the air, which creates fog.  Just as you can’t see in a car at night in fog because the fog scatters the light from your headlights, so would the light from the Big Bang have been scattered.  For 300,000 years or so the universe was the proverbial pea soup.

After 300,000 or so years the temperature was low enough to form elements, which are electrically neutral.  Light doesn’t interact with neutral elements so it could pass unhindered through the universe for the first time.

Two scientists, George Gamow and Robert Herman, had been working on proving the Big Bang Theory.  They suddenly realized that if the Big Bang Theory was correct and the theory about plasma cooling to allow formation of atoms, which in turn allowed light to pass unimpeded through the universe, the remnants of that light should still be visible today.  If it could be detected it would further prove then validity of the Big Bang Theory.  In fact, detection of this luminoues echo of the Big Bang would be almost conclusive proof of the Theory.  Conversely, if the light wasn’t found the Big Bang couldn’t have happened.

Hubble the Hero

The 100 inch (2.5 m) Hooker telescope at Mount...
The 100 inch (2.5 m) Hooker telescope at Mount Wilson Observatory near Los Angeles, California. This is the telescope that Edwin Hubble used to measure galaxy redshifts and discover the general expansion of the universe. At the time of this photograph, the Hooker telescope had been mothballed, although in 1992 it was refitted with adaptive optics and is once again in use. Keywords: 100 inch Hooker, telescope, Mount Wilson Observatory, Edwin Hubble (Photo credit: Wikipedia)

Edwin Hubble was already famous by 1924 but that year he became a celebrity.  A few years earlier he had met Grace Burke, daughter of a California millionaire.  Grace was already married when Hubble fell in love with her but in 1921 she was widowed when her husband, a geologist, fell down a vertical mineshaft to his death.  Grace and Edwin renewed their relationship and were married in 1924.  Hubble was working at the Mt. Wilson observatory about 15 miles from Los Angeles at the time.  With his marriage into money he gained entry to parties where movie stars and politicians mingled.  Hubble was gregarious and outgoing and soon the likes of Douglas Fairbanks and Cole Porter visited the Mt. Wilson observatory where Hubble regaled them with stories.

Hubble had heard of Slipher’s and others’ discoveries that the majority of galaxies are moving away from us.  He took it as his duty as the world’s foremost astronomer to solve this problem.  The 100-inch Mt. Wilson telescope was 17 times more powerful than Slipher’s.  Hubble spent countless hours staring through it at the night sky.  With his assistant Milton Humason he set about measuring the speed of the receding galaxies.

What they discovered was the first observational evidence to support Lemaitre’s and Friedmann’s theory that the universe is not static but is expanding.  Hubble plotted the distance of dozens of galaxies against their speed and discovered a linear relation.  In other words, if a galaxy was twice as far from earth as another, the first was moving twice as fast.  Instead of traveling at random speeds and in random directions, virtually all galaxies were traveling at speeds proportional to their distance and moving away from the Milky Way.

By running the movie in reverse, so to speak, Hubble showed that last year all galaxies were closer to us than now, a hundred years ago they were closer still.  Moreover, and this was the incredible part, since the velocity was in proportion to the distance, the more distant galaxies would arrive at the beginning point at the same time as the nearer ones.  A galaxy three times as far away moved three times as fast, so, assuming that the relative speeds were constant, there was a time in the distant past when all galaxies were gathered together in one region of the universe.

Hubble’s findings weren’t conclusive proof of the Big Bang (it still had not been so named) and Einstein and others still favored a steady state view of the universe.  But it did give ammunition to the expanding universe proponents and put the burden on the steady-staters to reconcile their view with this indisputable evidence of galactic movement.

Hubble’s discovery gave rise to what is known as Hubble’s Law.  This isn’t an exact law like gravity but is more of a rule of thumb.  What it does is allow the distance of a galaxy to be calculated by knowing its speed, or its speed to be calculated if the distance is known.  The most profound implication of Hubble’s Law is that the age of the universe can be calculated.  Using Hubble’s Law and the speed of various galaxies led to a conclusion that the universe is 1.8 billion years old.

The only problem with this age is that geologists have calculated the age of the Earth at around 4 billion years.  How can the Earth be older than the universe that contains it?  While Hubble’s discovery gave credence to a time of beginning or creation of the universe, it posed internal inconsistencies.

Nevertheless, Hubble had a showman’s sense of when to leave the stage.  Rather than stay around after his prime, he stepped down at the top of his game.  He did not get involved in the next Great Debate

over the steady-state vs. expanding universe.  He luxuriated in his celebrity status as the man who had expanded the universe from the Milky Way to a perhaps infinite number of galaxies, who had shown that all these galaxies are racing away from us and who, though he might not acknowledge it himself, had nurtured the seed of the notion that the universe began at a finite time in the past, thus giving some objective evidence that Genesis’ statement “let there be light” is more than just a poetic description.

The Doppler Effect

Everyone is familiar with the Doppler Effect; they just might not know the name.  We hear it every time we hear a police or fire truck siren.  You will note that the siren raises in pitch as the car is coming toward you and lowers as it travels away.  Sound waves are like light and water waves.  They have a wavelength, the distance from one crest to the next.  The closer the crests are to each other, or the shorter the wavelength, the higher the sound the wave makes.  Conversely, the longer the wavelength the lower the sound.

Doppler effect
Doppler effect (Photo credit: Wikipedia)

When the source of the sound is moving, such as when a siren is attached to a fire truck, as the truck comes toward us each wave that comes from the siren is slightly closer than the previous wave.  This has the effect of shortening the wavelength, raising the pitch of the siren.  Of course, the siren is emitting a steady pitch; we only perceive it to be higher or lower based on the movement of the fire truck relative to us.  As the truck moves away, each wave that is emitted is slightly farther away than the previous wave, so the wavelength is longer and the pitch drops.

The Doppler Effect is highly accurate and is the science behind radar guns.  A radar gun doesn’t actually emit radio waves (“radar” stands for RAdio Detection And Ranging) because the radio waves are too long to be reflected accurately by cars.  Radar guns actually use microwaves.  By measuring the change in frequency of the reflected microwave off a moving car, the gun calculates the speed of the car.

By the beginning of the 20th Century, the trifecta of spectroscopy, the Doppler Effect and more powerful telescopes allowed astronomers to make unparalleled strides in analyzing stars.  Their velocities could be measured accurately and by 1912 it was determined that  some stars were moving along at a few kilometers per second and some were zipping through the cosmos at over 50 km/sec.  To put this in perspective if a jet plane could travel 50 km/sec it would cross the Atlantic ocean in a couple of minutes.

In 1912 an amateur astronomer, Vesto Slipher, became the first person to measure the velocity of a nebula (recall that at this time the Great Debate over nebula vs. galaxy had not been resolved).  He discovered that the Andromeda Nebula was blue-shifted (meaning it is moving toward the Milky Way) to such an extent as to have a velocity of 300 km/sec.  Doubting his measurements he trained his telescope on the Sombrero Nebula (now galaxy) and discovered a red shift (meaning the Sombrero Galaxy is moving away from the Milky Way) that yielded a speed of 1,ooo km/sec., nearly 1% of the speed of light.  A plane traveling this fast would go from New York to London in about six seconds.

As more astronomers looked at the Doppler Effect on galaxies they discovered a very weird and unexpected result.  The vast majority of galaxies are moving away from the Milky Way.  Scientists expected some galaxies to be moving toward us while others moved away, but almost all were racing away as if the Milky Way had measles.

Various theories about why this is so were advanced but no consensus emerged.  Eventually Edwin Hubble, already famous for settling the Great Debate, would make another monumental discovery that would further support the Big Bang Theory.

Light: The DNA of the Universe

If you follow the various crime dramas on TV, you know that once the villain’s DNA is found the crime scene analysts can tell everything about him:  sex, age, height, weight, race, what he had for dinner last night and probably where he lives.  Whether that is real science or not, light tells just about everything there is to know about a star.

In 1842 French philosopher Auguste Comte tried to categorize certain things that would forever remain unknown.  Among those was “the chemical and mineralogical” makeup of stars.  He would be proven wrong within two years of his death.

Light is a form of energy.  Physicists think of light as being a wave, much like waves in water.  The wavelength of light is measured by the distance from the crest of one wave to the crest of the next.  The shorter the wavelength of light, the more energy it has and vice versa.  Humans tend to think of light only in terms of those wavelengths that the eye can detect, which range from the longest wavelengths of red to the shortest of violet.  Wavelengths longer than red are called infrared, while wavelengths shorter than violet are called ultraviolet.  Scientists, however, often lump all electromagnetic radiation under the heading of “light.”  Other forms of electromagnetic radiation are radio waves, which have wavelengths in the hundreds of meters (a meter is roughly a yard), to microwaves, exactly what are used in microwave ovens and are what the police really use in radar guns, and are still much longer than infrared light, to gamma and x-rays, which have very short wavelengths and thus high energy, which allows x-rays to penetrate solids.  The higher energy of the shorter wavelength light, such as x-rays and gamma rays, can cause damage to humans.   Gamma rays are one of the deadly emissions from a nuclear explosion.

Complete spectrum of electromagnetic radiation...
Complete spectrum of electromagnetic radiation with the visible portion highlighted (Photo credit: Wikipedia)

Since light is a form of energy scientists can use light to determine the temperature of a star.  An object heated to about 500 degrees Celsius (900 degrees Fahrenheit) begins to glow red, literally red-hot.  At 3,000 C (5,400 F), it begins to emit white light. So by analyzing the spectrum of light given off by a star, science can determine its temperature.

In 1752 Scottish physicist Thomas Melvill noticed that different substances emitted different colors when burned.  By carefully categorizing the colors emitted by the burning of various elements and comparing those to the light given off by a star the star’s composition can be deduced.  Melvill wasn’t expecting this nor was he looking for it.  His discovery illustrates the adage that most scientific discoveries are accompanied not by a cry of “Eureka!” but by a murmured “that’s funny.”

Each element has a distinctive color, which acts as its DNA, allowing it to be identified just by looking at it.  This combination of light, color and atoms is called spectroscopy.  The science of studying light emitted by objects is called spectroscopic emission.  The opposite phenomenon, absorption of certain light wavelengths by a substance, also exists and that is called spectroscopic absorption.  Spectroscopic absorption allowed scientists to determine the composition of the sun.  By noting which wavelengths were absorbed and therefore not visible in the light emitted from the sun, scientists could determine what elements were present in the sun that absorbs those wavelengths.

In addition to determining the composition and temperature of stars from starlight, the star’s velocity can also be found.  This stunning discovery was made by Thomas Huggins and his wife, Margaret, herself an accomplished astronomer and 24 years his junior.  When Thomas, at 84, was too feeble to clamber around a telescope, his young wife, only 60, was able to take over.

Science had long known that stars appear to change position in the sky relative to Earth and to other stars.  This movement across the sky is called proper motion.  However, proper motion is incremental and even with advanced technology is difficult to detect.  In addition, proper motion only tracks movement of a star laterally in the sky, as if all the stars were in the same plane.  Proper motion can tell nothing about the movement of a star either toward or away from the earth.

Mr. and Mrs. Huggins were able to combine spectroscopy with a piece of physics known as the Doppler Effect, after Christian Doppler, the Austrian physicist who discovered it, to determine the velocity of stars.  The Doppler Effect would become key in proving the Big Bang Theory.

How Big?

We’ve seen that one of the biggest hurdles astronomers faced was coming up with a way to measure the absolute distance to a star.  While the siriometer provided a relative method, since the distance to Sirius wasn’t known, all distances were relative to the unknown distance to Sirius.  There are a number of heroes and some heroines in the tale of how astronomy finally was able to come up with absolute distances, but probably the major technical advance that allowed calculation of distance was photography.

Looking at the sky, whether with the naked eye or through a telescope, discloses some stars but most are probably too faint to be seen.  When light hits the eye, it is processed by the brain and discarded.  No matter how long you stare at a star, the light that reaches you does not become cumulative.  However, the longer a photographic plate or film is left exposed to light the more the light shows up.  Over time what can’t be detected by the eye becomes a bright image on a plate.  By studying the plates instead of the night sky, astronomers were able to detect thousands, even hundreds of thousands, more stars.  But more importantly for determining distance, photographic plates of the same star taken over several days revealed that some stars change in brightness.  While scientists had been aware of variability, in the past it could only be described in vague terms, such as “Alpha Hydrae much inferior to Gamma Leonis.”  Photography allowed for objectivity.

Henrietta Swan Leavitt
Henrietta Swan Leavitt (Photo credit: Wikipedia)

One type of variable star, a Cepheid variable, proved most interesting.  The graph of the variation in brightness of a Cepheid has a distinctive shark fin shape, increasing in brightness quickly and declining rather more slowly.  The great thing about Cepheids is that they can be used to determine distance.  Henrietta Leavitt, who began as an unpaid volunteer at Harvard’s observatory, made a breakthrough discovery.  She focused her attention on the Small Magellanic Cloud, a cluster of stars that were known to be only “far away.”  By studying 25 Cepheids she identified she was able to determine their absolute brightness, not just relative brightness.

Some years later, Edwin Hubble identified a Cepheid in the Andromeda Nebula.  At the time the great debate over whether the Milky Way was all there is and nebulae were part of it, or whether nebulae were galaxies in their own right still raged.  By using Leavitt’s work, Hubble was able to calculate the distance to the Andromeda Nebula at approximately 900,000 light years.  Since it was known that the Milky Way is about 100,000 light years across, this conclusively proved that the Andromeda Nebula was so far away that it had to be a galaxy of its own.

Hubble was so astounded by his calculations that he delayed releasing them for several months.  When he finally did, he wrote to Harlow Shapely, the main proponent of the nebulae-as-part-of-the-Milky Way view.  Shapely replied by saying “here is the letter that ruined my universe.”

Edwin Hubble
Edwin Hubble (Photo credit: Wikipedia)

For the most part, nebulae were re-classified as galaxies.  A few nebulae (which originally meant a cluster of celestial objects having a cloud-like appearance) were identified as clouds of gas and interstellar dust.  Thus, with apologies to Star Wars, which made frequent use of “nebula” as a destination, that term really describes a gaseous dirt bag, hardly a proper place for a princess.

The universe had suddenly grown from the Milky Way to something that contained hundreds of thousands, if not millions, of Milky Ways.

What Does the Universe Look Like?

While Einstein, Friedmann, Lemaitre and others were sitting around thinking things up, another group of scientists, the astronomers, were combing the night sky looking through larger and larger telescopes, digging deeper into space and farther back in time.  If you look at the night sky with the naked eye it seems pretty much the same in any direction.  But peer through a powerful telescope and an amazing world opens.

English: Artist's conception of the spiral str...
English: Artist’s conception of the spiral structure of the Milky Way with two major stellar arms and a central bar. “Using infrared images from NASA’s Spitzer Space Telescope, scientists have discovered that the Milky Way’s elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to possess four major arms.” (Photo credit: Wikipedia)
Herschel’s 40-foot telescope, 1789. Deutsch: W...
Herschel’s 40-foot telescope, 1789. Deutsch: Wilhelm Herschels 40-Fuß-Spiegelteleskop) (Photo credit: Wikipedia)

Galileo built the first telescope.  In 1781, William Herschel, using a telescope he built himself, made a momentous discovery: the planet Uranus.  In 1789 he built an even larger telescope, a monster with a mirror 1.2 meters in diameter.  Unfortunately it was also 12 meters (over 40 feet) in length.  One of his main projects was to try to determine the distances to hundreds of stars.  He did this by making the assumption that all stars emit the same amount of light, so that the difference in brightness of stars is explained by how far away they are.  In the 18th Century scientists knew that brightness decreases in inverse proportion to the square of the distance.  Thus, if one star appears 1/4 as bright as another it is because that star is twice as far away.  As a standard he used the star Sirius, the brightest star in the sky.  A star only 1/9 as bright as Sirius must be three times as far away.  He called this distance a siriometer, so the fainter star was 3 siriometers away from Earth.  Herschel knew his assumption that all stars were equally bright was probably incorrect but, he figured that on average this was true and would result in a fairly accurate picture of the sky.

What Herschel discovered was that stars appeared to be clumped together in a disc, rather like a pancake.  Imagine that we are in the middle of the pancake and that raisins are sprinkled throughout it.  If we look down the length of the pancake we would expect to see many raisins or stars, but if we look up or down we would not expect to see too many.  This conformed to what Herschel observed: a band of stars stretching across the sky.  This had long been known to the ancients though they couldn’t tell that the milky band of light was a collection of stars.  This soon became known as the Milky Way.  At Herschel’s time the Milky Way was assumed to be the entire universe.  It was thought there was nothing outside of it.

As telescopes became better astronomers saw more and more blobs of light, which they called nebulae.  A debate arose over whether a nebula was part of the Milky Way galaxy or was an entire galaxy unto itself.  The two main protagonists in this debate, Harlow Shapely, who favored the view that nebulae were part of the Milky Way, and Heber Curtis, who argued that nebulae were separate galaxies.  Shapely believed that nebulae were clouds of gas where stars incubated.  Curtis argued that nebulae were scattered more or less symmetrically around the Milky Way but couldn’t be detected because of all the stars and interstellar dust in the plane of the Milky Way.

The debate was formalized in April, 1920, when the two met at the National Academy of Sciences in Washington.  At the end there was no clear-cut winner.  It would continue for three more years until Edward Hubble, probably the greatest astronomer of his generation, was able to show that the Andromeda Nebula was in fact a separate galaxy, the Andromeda Galaxy, some 900,000 light years from earth.