The cosmic microwave background radiation, or CMBR, is a relic of a time before the advent of stable atoms, where photons bounced between electrically charged protons and electrons, lending the early universe a fog-like glow. Roughly 400,000 years after the Big Bang, the universe had cooled enough for the electrons and protons to bond together into hydrogen atoms, canceling out their electric charges. The photons thus stopped their chaotic zigzagging, instead spreading out in roughly straight lines. These photons are what we now observe as the CMBR.

This phenomenon has allowed cosmologists to gather vital data regarding the formation of hydrogen in the universe. This was a chaotic process of recombination that took millions of years (the 400,000 year figure mentioned above is really just a rough indicator of when the process began) to fully resolve itself, as photons smashed apart many of the emergent hydrogen atoms. It was only as the universe expanded further that the atoms really had enough room to decisively come together, paving the way for a cosmos of matter, stars, and, ultimately, life.

Although the CMBR has been extraordinarily useful in revealing the history of the universe - after all, everything since the 400,000 year mark covers roughly 99.997% of all time - it seemingly blocks much investigation of the time before that and the kinds of processes that might have taken place, including the decay of exotic particles. But now scientists have figured out a way to peer even further back into the ancient cosmos by taking advantage of the other element besides hydrogen that formed in the primordial chaos.

Helium, being the heavier of the two elements, had double the electric charge of hydrogen in their nuclei and thus more quickly attracted the electrons needed to form stable atoms. Cosmologists have pegged the time of first attraction between helium nuclei and electrons at about 15,000 years after the Big Bang, with the second electrons needed to complete the atom being brought at around the 100,000 year mark. Both of these events took place significantly before the release of the CMBR, and the photons that interacted with these helium atoms will look significantly different from those that interacted with hydrogen.

Unfortunately, there are roughly a billion times the photons emitted by hydrogen as there are those emitted by helium, making them exceedingly difficult to find unless specifically looking for them. Still, the helium photons do bunch together at certain frequencies, meaning photon spikes at certain frequencies in the CMBR are a telltale sign. Once located, these helium photons will hopefully provide a window into an even earlier period of the universe's history than previously thought possible.

Searching for these photon spikes is probably years away, however. In order to locate these photon spikes, a satellite investigating the CMBR would have to scan frequencies from a fixed position. The European Space Agency's Planck Satellite, launched this past May, is currently charged with investigating the spatial patterns of the CMBR. This requires precisely the opposite approach, as Planck scans positions from a fixed frequency. As such, the hunt for helium photons will likely have to wait.

[Scientific American]

Martin Bojowald and Abhat Ashtekar began researching their theory of loop quantum cosmology (LQC), an approach to cosmology that combine’s Einstein’s theory of gravity with quantum mechanics. They have modeled the birth of our universe, exploring the mathematics of universe as it contracts back toward its point of origin.

Bojowald's major realisation was that unlike general relativity, the physics of LQC did not break down at the big bang. Cosmologists dread the singularity because at this point gravity becomes infinite, along with the temperature and density of the universe. As its equations cannot cope with such infinities, general relativity fails to describe what happens at the big bang. Bojowald's work showed how to avoid the hated singularity, albeit mathematically. "I was very impressed by it," says Ashtekar, "and still am."

The researchers have found that when applying LQC, the universe does not revert back to a singularity as it contracts. Instead of seeing a big bang, the models indicate that the universe experienced a big bounce, with a predecessor universe contracting as it ended and then reemerging as our new, expanding universe. If the theory proves correct, it could mean that our universe does not have a finite beginning and end but is, instead, part of a chain of universes that expand and then contract to give way to a brand new universe.

Did our cosmos exist before the big bang? [New Scientist]

In the 16th century, Copernicus hypothesized that the Earth is not the center of the solar system, but rather the sun is. Later, cosmologists expanded this idea into the Copernican Principle: Earth is not in a special place in the universe, therefore our observations of local space can be used to infer data about the rest of the universe. When astronomers observed that the universe appears to be expanding at an accelerating rate, they needed to add something to their equations to make it all make sense. That something is dark energy, which would have to exist in massive quantities (as yet, pretty much undetectable) to explain this expansion.

Here's the thing - the universe is really, really, really huge. Just the part we can see is almost incomprehensibly big, and there's a whole lot of universe we can't see. No one knows how big the whole universe is, but it's entirely possible that our part of the universe is just a tiny fraction of the whole. Physicists from Oxford University are considering the idea that the universe we can observe is actually anomalous, a giant void with a low density of matter. The rest of the universe may look substantially different. Doing some number crunching revealed that their model of the universe works without dark energy, but isn't quite as accurate as the current dark energy model. However, they need more observations of certain types of supernovae to refine their numbers - in a few months, their equations may look better with more data.

What's particularly cool is that this maverick theory that tosses a very accepted tenet of astronomy right out the window is being published in Physical Review Letters, one of the most respected physics journals. It sure beats excommunication. Image by: NASA.

Overturning Copernicus, eliminating dark energy. [Nobel Intent]

Tsunami invisibility cloak, dark energy v. the void, sorting nanotubes with light, and more. [EurekAlert!]

As Neil DeGrasse Tyson puts it in his book Death by Black Hole and Other Cosmic Quandaries:

With or without warp drives, the long-term fate of the cosmos cannot be postponed or avoided. No matter where you hide, you will be part of a universe that inexorably marches toward a particular oblivion.

Yikes. So what are the particular oblivions that we can expect?

1. Total heat death
If you're like me, chances are your thermodynamics class stopped being pure fun right around the time you learned about the second law. The second law introduces the concept of entropy, often described as a measure of disorder in a system, but really a measure of the system's unavailability to do work — the evenness with which energy is distributed. Once an ice cube melts in a glass of water, for example, there's no way that ice cube will ever be able to go back and do any more work. It's finito.

The same goes for most of the processes in the universe. The second law of thermodynamics tells us that any process, when it occurs, can either increase the entropy of the universe or leave it unchanged; it can't ever decrease the entropy. So when you think about it that way, it's only a matter of time until the entropy in the universe is at its maximum, and there's no room for any more processes to occur — including any kind of life.

2. The big freeze
As the Big Bang was occurring, the temperature of all the matter in the universe was extreme, on the order of trillions of degrees. In the approximately 14-billion-year history that's followed, however, the universe has continued to gradually expand, and so its average temperature has decreased along with it. Today astrophysicists estimate it to be about 2.7 degrees Kelvin.

Astrophysicists, however, will also tell you that the universe's expansion hasn't stopped. And physics mandates that with expansion comes cooling. Eventually, the average temperature of the universe will get all the way down to absolute zero; no matter how fantastic parka technology gets by that time, life will have to stop.

In case 2.7 degrees sounds to you like it's pretty close to zero, here's a nice thing to remember: Experts in the field agree that the heat in the universe should last us at least 10^10^26 more years.

3. A big crunch / big bounce
Our universe started with a big bang, didn't it? Well, perhaps that big bang was just the end of a previous universe's big crunch — it existed for some amount of time, happy and innocent, and then began to slowly shrink into itself until it collapsed. Collapsed, mind you, with a bang.

If this theory is true, it could mean that we're living in an oscillatory universe; whenever one clump of galaxies has run its course, it contracts and explodes to form another. The major difficulty astrophysicists have had supporting this theory is that it doesn't explain how a recurring universe like this would avoid total heat death. There's also the increasing evidence that the universal expansion will continue indefinitely, but our universe has certainly surprised us before.

4. The big rip
So the universe is continually expanding. Some postulate that it's expanding with increased speed toward a moment where everything in the universe will tear itself apart. First, gravity will become too weak compared to the overwhelming cosmological forces pulling everything out, and galaxies themselves would separate. Then, individual stars and planets would unbind; in the final end, every atom in the universe would lose that essential gravitational imperative holding their elements together, and all of creation would separate into total destruction.

For this, my friends, we've got about 50 billion years to go.

Honestly, though, despair is not the proper reaction to these theories. If you feel like studying quantum mechanics (and who doesn't?), there are plenty more exciting ways to look at the fate of our existence — you could be the one with the next great proposal for what will happen when we drop into a lower energy state, or what exactly we can expect from the supremely mysterious dark energy that occupies 73% of our universe. And if you've been reading io9, you know we've got your back: we're fans of the multiverse theory, and not just because it means that Doctor Who's Billie Piper is having her way with David Tennant in another plane of existence.

All of this is a problem for your distant future relatives anyway. Turn your brain on and give it your all, but you know these cosmic solutions will truly find their answers when the kids are listening to the 10^10^75 offspring of the Jonas Brothers.

Image from Wikipedia.

Earlier this week I pondered whether dark energy is just a new version of an outdated theory, but a team of astronomers in Antarctica is doing the hard work of trying to find out. The South Pole Telescope (SPT) uses 1,000 advanced optical sensors to peer at distant galaxy clusters looking for subtle variations in the cosmic background radiation. Those variations will give scientists a better idea of the structure of the universe, and whether or not dark energy is part of it.

The SPT is the largest Antarctic telescope. Despite the frigid cold of the region, the optics are further shielded from background heat by being chilled to a temperature not far from absolute zero. Photo by: The University of Chicago.

Cosmologists Probe Mystery Of Dark Energy With South Pole Telescope. [Science Daily]

Aether (also called ether) was a theoretical substance that supposedly permeated the entire universe, including solid matter, more or less evenly. While aether theories evolved over time, it was generally believed to be made of particles so tiny we couldn't detect them. The inherent properties of the aether determined many of the physical properties of the universe, such as the speed of light and the strength of gravity. These forces propagated as waves through the aether. Aether theory survived into the 20th century - Einstein even adapted it to fit his theory of special relativity, although it was so drastically changed that it was hardly aether theory at all. In his 1920 address "Ether and the Theory of Relativity," Einstein said:

The ether of the general theory of relativity is a medium which is itself devoid of all mechanical and kinematical qualities.

To be certain, neither theory is "bad science" in any way. They are the types of theories that physicists come up with when they are working out beyond the current observational abilities of humans. Eventually, physicists identified the dual wave/particle properties of electromagnetic energy. This, along with experiments that confirmed general relativity, negated the need for aether theory. Likewise, new experiments conducted with the Large Hadron Collider later this year could detect new particles like the Higgs boson that will give us additional clues to the physical makeup of the universe. Will they invalidate dark energy? Photo by: NASA.