Evidence for the Big Bang

planck-attnotated-580x372The Big Bang Theory has been the dominant cosmological model for over half a century. According to the theory, the universe was created approximately 14 billion years ago from an extremely hot, dense state and then began expanding rapidly. After the initial expansion, the Universe cooled and began to form various subatomic particles and basic elements. Giant clouds of these primordial elements later coalesced through gravity to form stars, galaxies, and eventually planets.

And while it has its detractors, most of whom subscribe to the alternate Steady State Theory – which claims that new matter is continuously created as the universe expands – it has come to represent the scientific consensus as to how the universe came to be. And as usual, my ol’ pal and mentor in all things digital, Fraser Cain, recently released a video with the help of Universe Today discussing the particulars of it.

big_bangAddressing the particulars of the Big Bang Theory, Cain lists the many contributions made over the past century that has led this so-called theory to become the scientific consensus has come to exist. They are, in a nutshell:

  1. Cosmic Expanion: In 1912, astronomer Vesto Slipher calculated the speed and distance of “spiral nebulae” (galaxies) by measuring the light coming from them. He determined most were moving away. In 1924, Edwin Hubble determined that these galaxies were outside the Milky Way. He postulates that the motion of galaxies away from our own indicates a common point of origin.
  2. Abundance of Elements: Immediately after the big bang, only hydrogen existed and compressed into a tiny area of space under incredible heat and pressure. Like a star, this turned hydrogen into helium and other basic elements. Looking out into the universe (and hence back in time) scientists have found that great distances, the ratios of hydrogen to basic elements is consistent with what is found in star’s interiors.
  3. Cosmic Microwave Background (CMB) Radiation: In the 1960’s, using a radiotelescope, Arno Penzias and Robert Wilson discovered a background radio emission coming from every direction in the sky, day or night. This was consistent with the Big Bang Theory, which predicted that after the Big Bang, there would have been a release of radiation which then expanded billions of light years in all directions and cooled to the point that it shifted to invisible, microwave radiation.
  4. Large Scale Structure: The formation of galaxies and the large-scale structure of the cosmos are very similar. This is consistent with belief that after the initial Big Bang, the matter created would have cooled and began to coalesce into large collections, which is what galaxies, local galactic groups, and super-clusters are.

These are the four pillars of the Big Bang Theory, but they are no means the only points in its favor. In addition, there are numerous observational clues, such as how we have yet to observe a stars in the universe older than 13 billion years old, and fluctuations in the CMB that indicate a lack of uniformity. On top of that, there is the ongoing research into the existence of Dark Matter and Dark Energy, which are sure to bear fruit in the near future if all goes well.

big_bang1In short, scientists have a pretty good idea of how the universe came to be and the evidence all seems to confirm it. And some mysteries remain, we can be relatively confident that ongoing experimentation and research will come up with new and creative ways to shed light on the final unknowns. Little reason then why the Big Bang Theory enjoys such widespread support, much like Evolution, Gravity, and General Relativity.

Be sure to check out the full video, and subscribe to Universe Today for additional informative videos, podcasts, and articles. As someone who used to write for them, I can tell you that it’s a pretty good time, and very enlightening!

News From Space: Big Bang Vs. Black Hole

big bang_blackholeFor decades, the Big Bang Theory has remained the accepted theory of how the universe came to be, beating out challengers like the Steady State Theory. However, many unresolved issues remain with this theory, the most notable of which is the question of what could have existed prior to the big bang. Because of this, scientists have been looking for way to refine the theory.

Luckily, a group of theoretical physicists from the Perimeter Institute (PI) for Theoretical Physics in Waterloo, Ontario have announced a new interpretation on how the universe came to be. Essentially, they postulate that the birth of the universe could have happened after a four-dimensional star collapsed into a black hole and began ejecting debris.

big_bangThis represents a big revision of the current theory, which is that universe grew from an infinitely dense point or singularity. But as to what was there before that remain unknown, and is one of a few limitations of the Big Bang. In addition, it’s hard to predict why it would have produced a universe that has an almost uniform temperature, because the age of our universe (about 13.8 billion years) does not give enough time to reach a temperature equilibrium.

Most cosmologists say the universe must have been expanding faster than the speed of light for this to happen. But according to Niayesh Afshordi, an astrophysicist with PI who co-authored the study, even that theory has problems:

For all physicists know, dragons could have come flying out of the singularity. The Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on.

black_holeThe model Afshordi and her colleagues are proposing is basically a three-dimensional universe floating as a membrane (or brane) in a “bulk universe” that has four dimensions. If this “bulk universe” has four-dimensional stars, these stars could go through the same life cycles as the three-dimensional ones we are familiar with. The most massive ones would explode as supernovae, shed their skin and have the innermost parts collapse as a black hole.

The 4-D black hole would then have an “event horizon”, the boundary between the inside and the outside of a black hole. In a 3-D universe, an event horizon appears as a two-dimensional surface; but in a 4-D universe, the event horizon would be a 3-D object called a hypersphere. And when this 4-D star blows apart, the leftover material would create a 3-D brane surrounding a 3-D event horizon, and then expand.

planck-attnotated-580x372To simplify it a little, they are postulating that the expansion of the universe was triggered by the motion of the universe through a higher-dimensional reality. While it may sound complicated, the theory does explain how the universe continues to expand and is indeed accelerating. Whereas previous theories have credited a mysterious invisible force known as “dark energy” with this, this new theory claims it is the result of the 3-D brane’s growth.

However, there is one limitation to this theory which has to do with the nearly uniform temperature of the universe. While the model does explain how this could be, the ESA’s Planck telesceop recently mapped out the universe and discovered small temperature variations in the cosmic microwave background (CBM). These patches were believed to be leftovers of the universe’s beginnings, which were a further indication that the Big Bang model holds true.

big_bang1The PI team’s own CBM readings differ from this highly accurate survey by about four percent, so now they too are going back to the table and looking to refine their theory. How ironic! However, the IP team still feel the model has worth. While the Planck observations show that inflation is happening, they do not show why the inflation is happening.

Needless to say, we are nowhere near to resolving how the universe came to be, at least not in a way that resolves all the theoretical issues. But that’s the things about the Big Bang – it’s the scientific equivalent of a Hydra. No matter how many times people attempt to discredit it, it always comes back to reassert its dominance!

Source: universetoday.com, perimeterinstitute.ca