 | Looking beyond the edge of space to the Empyrean abode of God beyond. Often said to be a 16th-century German woodcut, but
more likely published for the first time in 1907 in Weltall
und Menschheit, edited by Hans Kraemer. |
| Looking beyond the edge of space to the Empyrean abode of God beyond. Often said to be a 16th-century German woodcut, but
more likely published for the first time in 1907 in Weltall
und Menschheit, edited by Hans Kraemer. |
Creating a universe from nothing? |
| Fred Hoyle, one of the founders of modern astronomy, was an advocate of a 'steady-state' cosmology until his death in 2001, although he himself had created the term Big Bang in a broadcast lecture in 1952 (intended to be derisive; Maddox 2001). To account for the expansion of the universe, that could not be denied since Edwin Hubble's observations published in 1929, he postulated the continual creation of new matter. But in the early eighties, Alan Guth, Andrei Linde, Andreas Albrecht, and Paul Steinhardt elaborated on a radically different concept for which Guth had coined the term inflation (Guth & Steinhardt 1984). |
| Why couldn't we stay with good old Euclidean geometry, with Newton's laws of gravity? Why shouldn't things be simply as we would like to see them, with galaxies scattered across an endless space in tranquility, decently staying where God the Almighty put them? And why couldn't all living species stay as they ever were, and why have we been expelled from paradise? Well, why. Because we tried from the tree of knowledge, although God told us not to do so (Genesis 2: 17). |
| But we did. And now we know that galaxies are recessing from us, the faster the deeper we peer into space. And we know that this process must have started at some time deep in the past. Should we close our eyes to the fact? Since nature is open to observation by anyone who is courious enough (and persistent enough to get hands on the necessary instruments), it could not escape our notice that the history of our universe as we reconstruct it today begs for its extrapolation beyond the observable. If we trace back the paths of all these recessing galaxies we see today: where will it lead us to? |
| It leads us to a universe with progressively reduced distances and progressively increased temperature. At some point, the energy density was too high to allow the formation of stable atoms, closing for us the window of direct observation (see my essay on the Microwave Background Radiation), and at another point, our universe was nothing but an extremely hot, homogenous particle soup. That's the theory. But theory doesn't stop there. At temperatures above 1025 degrees, strange things are supposed to happen to our physical laws as we know them. Earlier than 10-30 sec after the Big Bang, the universe is supposed to have experienced a phase transition, with spectacular consequences. |
| Don't feel anxious now, that's only theory. The Large Hadron Collider presently in construction at CERN and scheduled to start operation in 2007 is hoped to produce collision energies of up to about 1 million GeV, corresponding roughly to a temperature of 1019 degrees, still at least 6 orders of magnitude away from the point of suspected phase transition. But just to continue with our exploration back into time: The addressed phase transition - according to theory - goes along with 2 events outside the scope of conventional physics: (A) Distances increase by at least 25 orders of magnitude within about 10-36 sec, starting at almost nothing before, and ending with a few cm after the event. Even light takes 10-10 sec to cross a distance of 3 cm, thus during "inflation", distances increase about 1026 times faster than the speed of light. Here, however, spacetime itself is expanding, and nothing is moving through spacetime faster than light. |
| (B) During phase transition, practically all matter existing today "crystallizes" (like snowflakes during the phase transition of water from vapor to solid) from a precursor that, before that transition, found room in a sphere measuring just 10-24 cm across. The old wisdom that nothing can be created from nothing, is saved by the concept that not only matter evolves, but also an equivalent amount of gravitational field energy. Without the latter, matter would not attract matter. It may appear like a bad trick, but in contrast to the positive energy of matter, in Einstein's equations the energy of a gravitational field is entered as a negative quantity (as a positive quantity, it would be repulsive and not attractive). For most physicists, this relationship might have appeared as a purely formalistic necessity. But already in the 40ies, the leading figures of cosmology tried to think about eventual practical consequences. |
| In his book "My World Line", George Gamow who had been the first after Hubble's discovery to propose a Big Bang (although not using the term), recalls a conversation with Albert Einstein during a walk through the streets of Princeton, on the apparent negative relationship between the energy of gravity and the energy of matter. At one point of the conversation Gamow raised the question of a star being created out of nothing, if positive and negative terms exactly would cancel each other out. The consequence of that innocent remark was a minor traffic jam, since Einstein stopped, contemplating, right in the middle of the street. This little story may provide some consolation for the "normal" thinker, that he is in best company feeling perplexed when taking higher mathematics at its words. |
| With the successful launch of the inflationary universe in the early eighties, all of a sudden particle physicists entered the stage of cosmology. They joyfully announced the unification of all forces they had been dreaming of for generations. Although they couldn't tell us exactly what existed in the very short epoch before transition, they speculated fervently about the laws of nature ruling the primordial particle zoo. The higher the temperatures, the more exotic the beasts (and the lower the chances of experimental verification). As the latest twist, old theories on a Big Crunch preceeding the Big Bang were revived. A recent Science paper (again co-authored by Steinhardt) predicts endless cycles of Bangs and Crunches, with cycling periods of several trillion(!) years (Steinhardt & Turok 2002, 2006). This would leave enough time before the next Crunch to think it all over with due profundity... |
| See
also my earlier essays on distant
galaxies and on cosmic microwave background radiation |
| 6/05 < MB
6/05 > 6/05 |
| A.H.Guth & P.J.Steinhardt (1984) The inflationary universe. Scientific American 250: 90-102 |
| J.Maddox (2001) Obituary: Fred Hoyle (1915-2001) Nature 413: 270 |
| P.J.Steinhardt & N.Turok (2002) A cyclic model of the universe. Science 296: 1436-1439 |
| P.J.Steinhardt & N.Turok (2006) Why the Cosmological Constant is small and positive. Science 312: 1180-1184 |
| See also John Gribbin's web pages cosmology for beginners |