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

What Would Hyperspace Really Look Like?

hyperspaceRemember those iconic scenes in Star Wars when the Millennium Falcon made the jump to hyperspace? Remember how cool it looked when the star field stretched out and then the ships blasted off? And of course, every episode of Star Trek was punctuated by a jump to warp, where once again, the background stars seemed to stretch out and then hurl on past the Enterprise.

Yes, for generations, this is how people envisioned Faster-Than-Light travel. Whether it consisted of rainbow-colored streaks shooting past, or a quick distortion followed by a long, blue tunnel of bright light, these perceptions have become a staple of science fiction. But one has to wonder… in a universe where FTL was really possible, would it really look anything like this?

hyperspace3Using Einstein’s Theory of Relativity, four students from the University of Leicester produced a paper in January of last year where they theorized what a jump to light-speed would really look like. Based on the theory that the speed of light is the absolute threshold at which elementary particles can move in this universe, the four students – Riley Connors, Katie Dexter, Joshua Argyle, and Cameron Scoular – claimed that a ship that can exceed c would have an interesting view.

In short, they claim that the crew wouldn’t see star lines stretching out past the ship during the jump to hyperspace, but would actually see a central disc of bright light. This is due to the Doppler effect, specifically the Doppler blue shift, that results in the wavelength of electromagnetic radiation, including visible light, shortening as the source of the light moves towards the observer.

Hyperspace. Nuff said?
Hyperspace. Nuff said?

As the ship made the jump to hyperspace, the wavelength of the light from the stars would shift out of the visible spectrum into the X-ray range. Meanwhile, Cosmic Background Radiation (CBR), which is thermal radiation that is spread fairly uniformly across the universe and is thought to be left over from the Big Bang, would shift into the visible spectrum, appearing to the crew as a central disc of bright light.

What’s more, even a ship like the Millennium Falcon would require additional energy to overcome the pressure exerted from the intense X-rays from stars that would push the ship back and cause it to slow down. The students say the pressure exerted on the ship would be comparable to that felt at the bottom of the Pacific Ocean.

red-shift-03However, if the ship in question took its time getting up to speeds in excess of the speed of light, there would be some interesting visual effects. Given how light and the color spectrum works, as a ship continued to speed up, the stars in front of the ship would experience blueshift (shifting towards the blue end of the spectrum), while those behind it would experience redshift (shifting towards the red end).

But the moment the threshold of light speed was passed, background radiation would be all that was left to see. And once that happened, the crew would experience some rather intense radiation exposure. As Connors put it:

If the Millennium Falcon existed and really could travel that fast, sunglasses would certainly be advisable. On top of this, the ship would need something to protect the crew from harmful X-ray radiation.

And as Dexter suggested, referring to Disney’s purchase of Lucasfilm for a cool $4.05 billion: “Disney should take the physical implications of such high speed travel into account in their forthcoming films.” I won’t be holding my breath on that one. Somehow, star lines look so much cooler than a mottled, bright disc in the background, don’t you think?

Hyperspace_HomeOneSources: gizmag.com, le.ac.uk.com