Our Special Time in the Universe

 

We know that we live in a special place. Earth is special as it supports the delicate conditions that have allowed us to evolve to our present state. I think it is fascinating to note that not only do we live in a special place, but the time in which we live is also remarkable.

Normally when we speak of time, we are referring to events that have or are occurring in a span that is relatively close to our own existence. Even when we discuss history, thousands of years ago, this is still very recent time as far as the universe is concerned. The time frame of which I speak is much broader, much deeper. We’re talking billions of years. Trillions of years. But trillions of years are peanuts for the universe. If the universe continues to be, and is not destroyed, then billions of years is still nothing compared to infinity. So here, when I say we live in a special time, I’m referring to a window of a trillion years, give or take.

So, what’s so special about our time? In Laurence Krauss’ book “A Universe from Nothing”, he demonstrates how our time is one when our ability to accurately observe and quantify our universe is a luxury. We live in a time when it is still possible for us to determine the size of our universe. This is possible because we can still see to the far edge of the universe, to the cosmic microwave background (the radiation that is left over from the big bang). This may not sound terribly impressive, but keep in mind that future civilizations will not have this luxury. Our universe is expanding, faster and faster, stretching space-time out as it does so. Eventually this expansion, if it continues to accelerate (which all evidence suggests that it will), will be stretching space-time out at a rate that is faster than the speed of light. Once this rate of expansion is reached, it will be impossible for light from these regions to ever reach other areas of the universe. Therefore, in a future civilization, on a different world, trillions of years from now, the greatest scientists of their era will look out through the lenses of the most powerful telescopes ever constructed and see nothing beyond their own galaxy.

This has other implications as well. Not only will these future civilizations be unable to see anything outside of their own galaxy (which will remain intact due to the local effects of gravity within the galaxy), but this will also mean that the expansion of the universe will also be undetectable. Without being able to detect the expansion, the now infamous dark energy will also remain in the dark, so to speak.

So, our time is unique in that we are able to learn key aspects of our universe that will be simply out of reach of our universal successors. The universe is a wonderfully mysterious place, and I for one feel tremendously lucky to be alive when we can appreciate intricacies such as this.

 

Sources:

http://www.youtube.com/watch?v=EjaGktVQdNg

Absolute Zero No Longer Absolute

Absolute zero, measured using the Kelvin scale, occurs when matter has reached the lowest possible level of entropy, when its atoms are utterly and totally ‘frozen.’ It is the coldest temperature anything in the universe can possibly reach, or so we thought.

Physicists at the Ludwig Maximilian University in Munich, Germany have done the impossible; they have created a quantum gas made up of potassium atoms that is colder than absolute zero.

Using lasers and magnetic fields, the infantile toys of researchers studying the quantum realm, the physicists were able to stabilize the atoms in a lattice arrangement. While the atoms normally repel each other at positive temperatures, the researchers decided to have some fun and abruptly alter the magnetic fields, causing all of the atoms to instantly attract. Ulrich Schneider, part of the team of physicists, explains that

This suddenly shifts the atoms from their most stable, lowest-energy state to the highest possible energy state, before they can react. It’s like walking through a valley, then instantly finding yourself on the mountain peak.

Whoa.  In the quantum world, anything goes.

Now, at a positive temperature, attraction between all of the atoms would cause the gas to become unstable and collapse in on itself, ultimately producing contempt and self loathing in already sensitive quantum physicists   Luckily, as usual for physicists, they protected the delicate balance of their emotions with trapping lasers, which were used to hold the atoms in place.  Boom! The result is:

The gas’s transition from just above absolute zero to a few billionths of a Kelvin below absolute zero.

Working with negative temperatures opens up all new realms of possibilities in the laboratory. Wolfgang Ketterle, a man with a better name than you, as well as a physicist and Nobel laureate at the Massachusetts Institute of Technology in Cambridge, reveals to us the profundity of this feat. He says that doing quantum experimentation while working with negative temperatures is like experimenting in an environment where:

you can stand a pyramid on its head and not worry about it toppling over. This may be a way to create new forms of matter in the laboratory.

By far, the weirdest part about the negative temperature gas is that it behaves identically to dark energy, the force that pushes the Universe to expand at an exponential rate despite the ever persistent pull of gravity.  The atoms in the gas also seem to want to collapse inward, but the negative temperature holds them in place.  Schneider remarks that:

It’s interesting that this weird feature pops up in the Universe and also in the lab.  This may be something that cosmologists should look at more closely.

Researchers believe negative temperatures will give rise to the creation of matter with anti-gravitational properties, rising, despite gravity throwing a temper tantrum over wanting it to fall. For all you Egyptian pyramid conspiracy theorists out there, here’s some extra fodder for the anti-gravity theories.  The Egyptians must have created negative kelvin temperatures first!

 

Sources:

http://en.wikipedia.org/wiki/Absolute_zero

http://www.sciencemag.org/content/339/6115/52