By Matthew Paris | December 04, 2012 2:59 pm

The Big Bang

We all know the universe started with a big bang; that it may have also been preceded by a big crunch, but what about in between the big bang and the big crunch? A new study suggests that in that infinitely condensed soup of all of existence, a dash of antigravity was added. Yes, ANTI-gravity–the opposite of what holds everything together– played a part in the time before the universe was born into the cosmic abyss.

If you’re not familiar with the story, it goes like this: before our universe came into being, all matter, energy, and everything in between existed in some form and then contracted and crunched together, hence the big crunch, until all this stuff was packed into one infinitesimally small ball of everything. The force of everything in existence coming together recoiled and this little bounce-back created quite a big bang, spewing all of that matter and energy back into the void from whence it came, thus spawning the universe we know today.

The big bang and subsequent history. Link

Now, what about antigravity? First, let’s briefly get acquainted with antigravity. It isn’t as scary and complex as it sounds – antigravity is just that: the opposite of gravity; normally matter is attracted to other matter, but when antigravity’s in charge, matter is repelled by other matter. According to “Antigravity and the big crunch/big bang transition,” in that tightly-packed ball of everything, antigravity took the reins for a second. Thankfully antigravity isn’t a delinquent – it simply took all that matter and energy for a quick spin before returning it to the little ball it came in. Had antigravity run off with all that matter and energy, our universe would be a very different place: we wouldn’t have gravity to hold our stars, planets, moons, and galaxies together. If that were the case, we wouldn’t have our little blue and green planet that we like so much!

Historians are good at looking at the past and explaining what happened, but the big bang was 13.7 billion years ago. All of the primary documents of this cataclysmic explosion are stars and galaxies that are billions of light years away and even they can’t tell us everything, so how did researchers figure out that there was a period of antigravity such a long time ago? Well as it turns out, these physics detectives have an ace up their sleeve: math. Complicated, mumbo jumbo math.

Behold: the universe. Link

The authors of the aforementioned article used a series of equations, including the one above, to model the behavior of the universe while it was in its birth throes. To understand the main figures of the study, you need to understand two terms: isotropy and anisotropy. Like antigravity, these terms are much less daunting than they look. Isotropy is a property of matter in which it is directionally independent, having no preferred no direction. Anisotropy is the opposite: anisotropic matter is directionally dependent, meaning that it likes to have things happen in one direction as opposed to another. To illustrate that, imagine a wooden plank. Wood is an anisotropic material; in other words, its preferred direction is along the grain. If you try to split a wooden plank perpendicular to the grain, it is far more difficult than if you split it along the grain.

What does this have to do with antigravity? When modeling the behavior of the universe, researchers produced two graphs: one in which isotropy is included in the equations and one in which anisotropy is included.

Figure (a) includes isotropy and figure (b) includes anisotropy. Link

The graphs model the trajectory of matter and energy and as you can see, when isotropy is included in the equations (to recap: this means that all this matter and energy has no preferred direction), the trajectory is a mess. Where is the big crunch? Where is the big bang? Everything just seems to be going all over the place, but now look at the second graph. Much neater, isn’t it? The second graph includes anisotropy (again, anisotropic matter does have a preferred direction), which produces a much simpler view of events: matter and energy goes toward the origin (0,0), representative of the point at which everything condenses, loops around back to the origin (this loop is antigravity’s joy ride), then goes away from the origin. As labeled on the figure itself, the sequence is gravity, crunch, antigravity, bang, gravity. Simple as that!

Still with me? Alright, let’s review. As we now know, all matter and energy contracted to a single point (the big crunch), went through a brief period of antigravity, then expanded back into the blackness where it originated (the big bang). Researchers discovered the period of antigravity by using equations to model the universe’s behavior. The primary factor in these equations was the inclusion of isotropy versus anisotropy – no preferred direction versus preferred direction. The anisotropy model gave them a clear graph of the big crunch, the antigravity period, and the big bang.

The birth of the universe is one of life’s big mysteries, but as researchers continue to study it, the closer we’ll come to understanding it in its entirety. We figured out that there was a flash of antigravity between the big crunch and the big bang and now the next step is figuring out what things were like before the big crunch. When this first comes to light, you and your 13.7 billion year history lesson will be on the front line, ready to delve deeper into the history of the universe!

Further Reading: “Ekpyrotic universe: Colliding branes and the origin of the hot big bang”

References: Bars, I., Chen, S., Steinhardt, P., Turok, N. (August, 2012). Antigravity and the big crunch/big bang transition. Physics Letters B, 715. Retrieved from: http://www.sciencedirect.com/science/article/pii/S0370269312008350#

Categorized under: Astrophysics, Quantum Physics
 
For more popular science writing, return from whence you came.