Tag Archives: cosmology

Goodbye, Big Bang?

Everyone knows about the Big Bang, right? The explosion-into-being of the entire universe, however many billions of years ago? Of course they do. Trouble is, the Big Bang has always been something of a fudged theory… and now Wun-Yi Shu of the National Tsing Hua University in Taiwan has come up with a new theory that fits a lot of observed evidence far more thoroughly… while dumping on some accepted truths.

Shu’s idea is that time and space are not independent entities but can be converted back and forth between each other. In his formulation of the geometry of spacetime, the speed of light is simply the conversion factor between the two. Similarly, mass and length are interchangeable in a relationship in which the conversion factor depends on both the gravitational constant G and the speed of light, neither of which need be constant.

So as the Universe expands, mass and time are converted to length and space and vice versa as it contracts.

This universe has no beginning or end, just alternating periods of expansion and contraction. In fact, Shu shows that singularities cannot exist in this cosmos.

As with all such theories, not everything fits perfectly:

One of the biggest problems he faces is explaining the existence and structure of the cosmic microwave background, something that many astrophysicists believe to be the the strongest evidence that the Big Bang really did happen. The CMB, they say, is the echo of the Big bang.

How it might arise in Shu’s cosmology isn’t yet clear but I imagine he’s working on it.

Even if he finds a way, there will need to be some uncomfortable rethinking before his ideas can gain traction. His approach may well explain the Type-I supernova observations without abandoning conservation of energy but it asks us to give up the notion of the Big Bang, the constancy of the speed of light and to accept a vast new set of potential phenomenon related to the interchangeable relationships between mass, space and time.

So, yeah, bit of a revolutionary idea. Reading stuff like this always makes me wish I’d knuckled down more at college and gotten to grips with the heavy-lifting end of physics; that way I might have ended up making a living from speculating about how the universe works. What could be more fun?

And while we’re talking cosmology, here’s a Fermi Paradox rethink [via SlashDot]:

… a new approach by Igor Bezsudnov and Andrey Snarskii at the National Technical University of Ukraine.

Their approach is to imagine that civilisations form at a certain rate, grow to fill a certain volume of space and then collapse and die. They even go as far as to suggest that civilisations have a characteristic life time, which limits how big they can become.

In certain circumstances, however, when civilisations are close enough together in time and space, they can come into contact and when this happens the cross-fertilisation of ideas and cultures allows them both to flourish in a way that increases their combined lifespan.

[…]

The parameters that govern the evolution of this universe are simple: the probability of a civilisation forming, the usual lifespan of such a civilisation and the extra bonus time civilisations get when they meet.

The result gives a new insight into the Fermi Paradox. Bezsudnov and Snarskii say that for certain values of these parameters, the universe undergoes a phase change from one in which civilisations tend not to meet and spread into one in which the entire universe tends to become civilised as different groups meet and spread.

Bezsudnov and Snarskii even derive an inequality that a universe must satisfy to become civilised. This, they say, is analogous to the famous Drake equation which attempts to quantify the number of other contactable civilisations in the universe right now.

Of course, the only way to prove the theory is to wait until we can get more data… so you might want to read a book or something in the meantime.

Another speculative bubble

We may be in a bubble:

Earth may be trapped in an abnormal bubble of space-time that is particularly void of matter.

Scientists say this condition could account for the apparent acceleration of the universe’s expansion, for which dark energy currently is the leading explanation.

“If we lived in a very large under-density, then the space-time itself wouldn’t be accelerating,” said researcher Timothy Clifton of Oxford University in England. “It would just be that the observations, if interpreted in the usual way, would look like they were.”

One reason why this theory still isn’t widely accepted:

One problem with the void idea, though, is that it negates a principle that has reined in astronomy for more than 450 years: namely, that our place in the universe isn’t special.

When Nicholas Copernicus argued that it made much more sense for the Earth to be revolving around the sun than vice versa, it revolutionized science.

Since then, most theories have to pass the Copernican test. If they require our planet to be unique, or our position to be exalted, the ideas often seem unlikely.

This is obliquely tied to the problem of the apparent un-arbitraryness of our universe: a key scientific and philosophical problem for the 21st Century – why is it that the universe seems to be conveniently set up for life.

[via Slashdot][image from Jeff Kubina on flickr]

Dark matter, dark energy…and now, dark flow

800px-Big_bangIf this doesn’t boggle your mind, your mind is un-boggleable (Via Space.com):

Patches of matter in the universe seem to be moving at very high speeds and in a uniform direction that can’t be explained by any of the known gravitational forces in the observable universe. Astronomers are calling the phenomenon “dark flow.” The stuff that’s pulling this matter must be outside the observable universe, researchers conclude.

***

A theory called inflation posits that the universe we see is just a small bubble of space-time that got rapidly expanded after the Big Bang. There could be other parts of the cosmos beyond this bubble that we cannot see. In these regions, space-time might be very different, and likely doesn’t contain stars and galaxies (which only formed because of the particular density pattern of mass in our bubble). It could include giant, massive structures much larger than anything in our own observable universe. These structures are what researchers suspect are tugging on the galaxy clusters, causing the dark flow.

“The structures responsible for this motion have been pushed so far away by inflation, I would guesstimate they may be hundreds of billions of light years away, that we cannot see even with the deepest telescopes because the light emitted there could not have reached us in the age of the universe,” Kashlinsky said in a telephone interview. “Most likely to create such a coherent flow they would have to be some very strange structures, maybe some warped space time. But this is just pure speculation.”

Even though I was a teenager in the 1970s, I don’t say this very often, but…far OUT!

And I mean that literally.

(Image: Wikimedia Commons.)

[tags]cosmology, Big Bang, astronomy, outer space[/tags]

Time is A One Way Street…

TimeThe June 2008 issue of Scientific American sets out to answer a very perplexing question:

Why does time only move forward?

To find the answer, according to Sci-Am and Mr. Sean M. Carroll, we have to start looking at a very unlikely place:

To account for it, we have to delve into the prehistory of the universe, to a time before the big bang. Our universe may be part of a much larger multiverse, which as a whole is time-symmetric. Time may run backward in other universes.

The article is filled with high-end physics and a bit of science jargon, but Mr. Caroll puts uses neat little analogies to explain difficult concepts:

The asymmetry of time, the arrow that points from past to future, plays an unmistakable role in our everyday lives: it accounts for why we cannot turn an omelet into an egg, why ice cubes never spontaneously unmelt in a glass of water, and why we remember the past but not the future. And the origin of the asymmetry we experience can be traced…back to the orderliness of the universe near the big bang. Every time you break an egg, you are doing observational cosmology.

All in all, it’s a very interesting article and well worth a read. Some of the concepts used in the article are highly science fictional and are prime idea fodder for stories about multiverses and time travel. In fact, for those who’ve read River of Gods, may recognize the inspiration for ideas in that novel presented in this article. [image by gadl]