How Would You Graph It?

Our friend Steve is fascinated with what happened before the Big Bang, the theorized birth of the universe that occurred some 13.7 billion years ago. He is always asking me, “What’s before the Big Bang?” His question is partly motivated by sheer interest, but also because he runs a company that sells planetarium systems that allow users to model 3D data sets on their planetarium domes. You can load any data set onto the system and fly through it. So, of course, we loaded the COBE and WMAP data, which depict the last flickers of the Big Bang as seen at 2.73 degrees Kelvin. Now, if you fly out through that data set, you can theoretically be OUTSIDE the last flickers of the Big Bang. So, while you can’t do that in real life, the exercise does hold a certain fascination.

Physicist Martin Bojowald at Penn State University has been thinking about the same question, too, but from a physicist’s standpoint. His answer is that there may well have been another universe that collapsed, and through that action, gave birth to our own universe. He has developed a mathematical model that details the properties of a quantum state (that is, the state of a particle described by its position and momentum expressed in quantum numbers) as it travels through what he calls the “Big Bounce.” This bounce replaces the Big Bang as the event that began our universe. What’s more, if this quantum state can be studied, scientists could glean something about the earlier universe, although we’d never know if we are correct about what it tells us.

Now, that probably sounds pretty handwavy, but it’s not to a physicist, one of those legions of scientists who work to understand the atomic structure of everything that exists. To understand this (and you can read more about his work here), you have to know about the quantum state. And quantum phsyics, which is a term that gets thrown around whenever somebody wants to point out the geekiest thing you could think of to study.

Quantum physics is a way of explaining the physical behavior of the small particles that make up atoms: electrons, protons and neutrons. You can’t exactly observe these babies in real time, but you can figure out what states they can be in and use mathematical models to map those states. That’s more or less what Dr. Bojowald and his colleagues are doing. But, they’re taking things one step further by using something called “Loop Quantum Gravity,” the quantum theory that does to spacetime what quantum physics does to particles. That is, it tries to look at spacetime in discrete units and describe those units, in particular, the high energies present at the beginning of space and time.

The researchers are using this theory to trace the universe back through time. They are finding that the universe at its beginning point had a minimum volume that was not zero. It had a maximum energy that was not infinite. Then they applied the mathematical equations of their theory to make a model of the universe, and take it as far back as they could. What they found was that the model produces valid mathematical results past the point of the classical Big Bang–that is, it seems to describe conditions BEFORE the the birth of this current universe. So, theoretically now, the scientists have a way of looking through a quantum physics window into the time before the Big Bounce.

This may all sound quite technical, and it is. But, since we can’t know for sure what happened before the creation of THIS universe, models (based on solid observational evidence) are our best bet at figuring out what happened ‘way back then. And, it doesn’t exactly answer Steve’s question. In fact, it raises more!

Here in the northern hemisphere (planet Earth) we just celebrated the summer solstice yesterday. In the southern hemisphere people celebrated winter solstice. Summer solstice is the occasion to celebrate if you like long, warm, sunny days and short nights; winter solstice usually means colder weather, shorter days, longer nights.

“Solstice” is another of those words that comes down from an ancient tongue (Latin, in this case). It’s two words jammed together: sol for “Sun” and sistere “to stand still.”

Does the Sun really stand still on this day? Well, that’s an interesting question. It depends on the frame of reference you’re using. The Sun is moving through space as part of the Milky Way Galaxy, which is, itself, moving through space as part of the Local Group of Galaxies, which is itself moving through space as part of a supercluster of galaxies, which is itself moving with the expansion of the universe, but possibly also affected by the gravitational pull of dark matter and the effect of dark energy.

Okay, that can get confusing really fast. So, let’s narrow it down a little, to just the motion of the Sun and Earth with respect to each other. The truth is, Earth rotates around the Sun and it also spins on its axis. We have day and night because Earth turns on its axis. We’re sitting on the surface of the planet, riding along as it turns on its axis. So, as the planet turns, things in the sky look like they’re moving across the sky. In reality, they’re more or less sitting still while our point of view is changing. It’s exactly like being on a merry-go-round as it spins around. Everything NOT on the merry-go-round isn’t moving, but it looks like it is.

So, Earth is spinning on its axis, which is tilted. That tilt, plus the apparent motion of the Sun across our sky each day, holds the key to understanding “solstice.” In northern hemisphere summer, the northern hemisphere is tilted toward the Sun. This lets a LOT more warmth and light from the Sun reach the northern hemisphere. At the same time, the southern hemisphere is receiving less light and warmth, and experiences winter. (Note: Earth is NOT closer to the Sun during this time.)

Solstice happens because as Earth makes its yearly trip around the Sun, spinning its axis, the perceived position of the Sun changes. NOT just the east-west motion we see every day, but also north-south. The Sun appears to move farther north in the sky from December to June, as the tilt of our axis brings more of the Northern Hemisphere into more sunlight. Then, from June to December, the Sun appears to move back to the south. It reaches its northernmost point in the sky on June 21, where that slow northward motion seems to stop for a day or two. Then, as the planet continues on its trip around the Sun, the tilt slowly changes, and the Sun appears to head south again.

In the southern hemisphere on June 21, the Sun is also at its northernmost point, which means that half of the planet is getting less warmth, less sunlight, and things get cold.

On December 20, the date of the other solstice when the Sun appears to “stand still” at its southernmost point in the sky, the northern hemisphere is getting less sunlight and has lower temperatures. In the southern hemisphere on the same day, it’s warmer and summer is in full bloom.

The ancients, who watched the sky pretty closely for a variety of reasons, noted that “stoppage” with the term “solstice.” Since it seemed to coincide with warm weather, a good growing season, and increased amounts of food, solstice time seemed a great time to celebrate.