Excerpt from Chapter 4 of Genesis and Genes

Genesis and Genes is now available in Israel, the UK and the USA. It is expected in South Africa in January 2013. In the meantime, I intend to post a number of sample passages. Here is an excerpt from chapter 4.

***

Nobody – including astronomers and cosmologists – knows what the universe is made of. Visible matter – the kind of stuff that people and planets are made of – is outweighed by a factor of 6 or 7 by invisible, cold dark matter. To put it another way, something like 95% of the universe is made up of stuff we can’t detect, except that it seems to exert a gravitational pull. Here is how one distinguished astronomer and author, James Kaler, puts it:

“Our Galaxy, its stars revolving around the center under the influence of their combined gravity, is spinning too fast for what we see. Galaxies in clusters orbit around the clusters’ centers under the influence of their mutual gravities, but again, they move faster than expected. There must be something out there with enough of a gravitational hold to do the job, to speed things up, but it is completely unseen. Dark matter… We have no idea what constitutes it. Rather, there are many ideas, but none that can be proven.” [Heaven’s Touch, James B. Kaler, Princeton University Press, 2009, page 16.]

A popular history of astronomy weighs in with this:

“Over 90 per cent of our Universe is invisible – filled with particles of mysterious dark matter. And astronomers have no idea what it is. Theoretical physicists working on the kinds of particles produced in the Big Bang say that dark matter cannot be anything ordinary – it has to be something very exotic.” [The History of Astronomy, Heather Couper and Nigel Henbest, Firefly Books, 2007, page 240.]

I don’t wish to labour the point, but I must. The public is subjected to absolute statements about our knowledge of the universe and its history so frequently that the average person is simply inured to the fact that there remain basic questions about our cosmic abode. To wit, we do not know what it is made of. Consider this. The most ambitious project in astronomy in the early 21st century is the SKA, or Square Kilometre Array, a network of radio telescopes that is gargantuan in every respect: complexity, size and cost. An article in TIME magazine about the instrument begins by asking the project manager what it is that astronomers wish to discover with this machine: 

For someone whose job title could read Man Most Likely to Blow Your Mind, Bernie Fanaroff looks pretty conventional… Consider the fact, says Fanaroff, that we have no idea what 96% of the universe is made of. Cosmologists have known for some time that only 4% of the universe is stuff like dust, gas and basic elements. Dark matter, says Fanaroff, accounts for 23% to 30%; dark energy makes up the rest. (Dark, Fanaroff explains, is the scientific term for “nobody knows what it is.”) [TIME Magazine, January 30th, 2012, page 40. The article is entitled Africa’s Eye on the Sky.]

 That’s not an exaggeration – nobody knows anything significant about what makes up 96% of the universe. And this is acknowledged even by those who pretend to be able to answer ultimate questions in naturalistic terms. Lawrence Krauss is a world-famous physicist and an ardent atheist. His latest book, A Universe from Nothing: Why There Is Something Rather than Nothing (Free Press, 2012) was reviewed in the January 2012 issue of Nature, the world’s most respected science journal. Nature appointed Caleb Scharf, an astrobiologist at Columbia University, to aggrandise Krauss’s ideas about the universe popping out of absolutely nothing, but even he could not hide the gigantic lacuna in Krauss’s thesis: 

“He notes that a number of vital empirical discoveries are, ominously, missing from our cosmic model. Dark matter is one. Despite decades of astrophysical evidence for its presence, and plausible options for its origins, physicists still cannot say much about it. We don’t know what this major mass component of the Universe is, which is a bit of a predicament. We even have difficulty accounting for every speck of normal matter in our local Universe.” [Caleb Scharf, Cosmology: Plucked from the vacuum. Nature 481 (26 January 2012), p. 440]

 It is crucial to appreciate that dark matter is not something that was initially discovered in a laboratory, and whose existence was then used to explain some phenomenon. It is also not an entity whose existence was implied by some cosmological theory, and then applied to the problem of energetic stars. Dark matter is entirely hypothetical. Its existence was postulated to explain how the stars in spiral galaxies can orbit at such breakneck speeds without being flung off into the void. In other words, when astronomers tallied up all the mass in the universe, they came face to face with a phenomenon which they could not explain using known physical laws: those laws would indicate that stars in spiral galaxies should indeed be flying off in all directions. Since they aren’t, there must be something out there to prevent them from doing so. What that something is remains anybody’s guess, as Professor Kaler pointed out above. Many astronomers believe that there is matter out there; matter which for whatever reason, we cannot see. This is why they refer to this hypothetical entity as dark matter. They appear to have considerable fun in speculating on the nature of this hypothetical matter: is it made up of MACHOs (Massive Compact Halo Objects)? Or is it WIMPs (Weakly Interacting Massive Particles)?

But since the whole exercise is built on speculation as to what could possibly be acting as a brake on those wayward stars, other scientists do not believe that dark matter even exists. And there is nothing to contradict their view. All you have to do is propose a plausible mechanism to restrain energetic stars from flying off into the cosmic sunset. Various problems with the dark matter model led Mordehai Milgrom, now at the Weizmann Institute in Rehovot, Israel, to suggest in the 1980s an alternative to dark matter, known as Modified Newtonian Dynamics, or MOND. The basic idea of MOND is that the force of gravity is not constant. Below a critical threshold of acceleration, gravity is stronger than what Newtonian theory predicts. This enhanced gravity ensures that stars remain bound to their galaxies. According to MOND theorists, there isn’t some mysterious matter out there, in such copious quantities as to dwarf the kind of stuff we are familiar with. Rather, one of the most fundamental and familiar forces of all – gravity – is not as familiar as we thought.

Whether the dark matter theory, MOND or neither is correct, the fact remains that when it comes to dark matter, astronomers are in the dark. We have little understanding of the stuff of the universe. It could well be that there is some other phenomenon that keeps stars in their orbits, of which nobody is currently aware. This could dramatically change our picture of the universe, and how currently-understood laws interact with this new phenomenon. To speak of proof regarding the validity of cosmological hypotheses to do with the ancient, unobserved past, when we have yet to learn some basic facts about the universe we inhabit now, is grossly premature.

To complicate things further, throw in some dark energy. This is not techno-speak from a Star Wars film. It is a phenomenon, discovered in the late 1990s, which appears to cause the universe’s expansion to accelerate. And this is not mere musing on a blackboard. The 2011 Nobel Prize in physics was awarded to a trio of astronomers for their discovery of this phenomenon. Adam Riess, Brian Schmidt and Saul Perlmutter were also acknowledged by the journal Science, which named their findings the Breakthrough of the Year in 1998. The problem is that nobody knows what this force could be. According to cosmologist Michael Turner of the University of Chicago, quoted in the January 2006 issue of New Scientist, “Cosmic acceleration is the biggest mystery in all of science.” The magazine went on to report that “… at a meeting of the American Astronomical Society (AAS) in Washington DC, the mystery deepened when Brad Schaefer of Louisiana State University in Baton Rouge reported that dark energy appears to be changing – rapidly. Though his experimental method left most cosmologists unconvinced, the result stressed how little we know about dark energy and the need for different approaches.” [Emphasis added]. Needless to say, if there is a force which is accelerating the universe’s expansion, and especially if its strength is varying, attempts to estimate the expansion of the universe in the past – and thus to infer its age – are enormously complicated. It may well be impossible to do so. Professor Kaler again:

“But we have even less of an idea where this [dark] energy comes from than we do about the nature of dark matter. So to dark matter, add dark energy. Either that or something is terribly amiss with our concept of gravity.” [Heaven’s Touch, James B. Kaler, Princeton University Press, 2009, page 16.]

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