Posted on 01/05/2005 7:18:54 AM PST by PatrickHenry
Astronomer Royal, Sir Martin Rees talks about the conditions for life. How unique is our world? Is the universe itself just the byproduct of many failed, sterile or stillborn universes that might have preceded it?
Helen Matsos: I was recently at a gathering of scientists, including notables such as Mitchell Feigenbaum, Oliver Sacks, and Neil deGrasse Tyson, and discovered you are much admired among this group. For instance, Neil referred to you as one of the last great gentleman astronomers of our time.
Martin Rees: (laughs) Does he mean it as compliment or not?
Mastos: Maybe he was referring to your title of Astronomer Royal. My understanding is that this role dates back to 1675, and was established to rectify the tables of star motion used for navigation. I'm wondering what's the modern-day relevance of this role.
REES: The quaint antique title indeed goes back to 1675, when the Royal Observatory was set up in Greenwich and the person in charge was given this title. The reason there is a title of Astronomer Royal, but no Chemist Royal or Physicist Royal, is that those other sciences were not professionalized and supported by governments until much later. Astronomy is one of the oldest sciences -- perhaps the oldest after medicine - and may be the first to do more good than harm.
But in the last 50 years, British astronomy has been making use of telescopes overseas with clearer skies, and the Greenwich Observatory is now essentially a museum. The title of Astronomer Royal was made an honorary title given to a senior academic astronomer. So my "day job" is being a professor at Cambridge University, and the title is purely honorary.
Mastos: Britain has such a rich history of supporting science and producing brilliant scientific minds. For instance, we're sitting here in Cambridge, looking across the green to where Isaac Newton worked and lived. What is Britain's role in the field of science today?
REES: It's true we have a proud tradition of science, from Newton through Darwin, James Clerk Maxwell, J.J. Thomson and many others.
Circumstances are rather different today, because government support is now more important than private patronage. But in the UK, you still have a strong tradition in science, partly because the British government has been more enlightened than many other European governments in providing a growing science budget. We hope to be able to maintain our competitiveness with the United States. We're much smaller, of course, but in terms of quality we can be a world force in science.
Mastos: In your book, "Just Six Numbers," you say there are six numbers that dictate the state of the universe, and that if any one of them were slightly different, then life as we know it would be impossible. Are any of your numbers related to ones in the Drake equation, which calculates the probability of life in the universe?
REES: We don't really know the likelihood of life because the uncertainties in the Drake equation, which still are still very large, are the probabilities that life gets started given the right kind of initial soup. Astronomers can't say whether life is likely or unlikely, because the most uncertain terms in the Drake Equation are the terms biologists have to solve for us.
Mastos: Then what can astronomers predict based on your six numbers?
REES: Astronomers can say what the necessary conditions are for life, but not the sufficient ones. In order for life to develop, there have to be habitats in the universe that are stable, are warmed by a star, and contain not just hydrogen but all the elements in the periodic table, like oxygen, carbon, and phosphorus, that are important for life.
In the last few decades, astronomers and cosmologists have been able to understand how our physical universe has evolved over nearly fourteen billion years, from its beginnings to the so-called big bang to its present state with galaxies, stars, and planets. We are starting to understand how stars and galaxies formed as the cosmos cooled down from its hot initial state. Those first stars were fueled by the same process of an H-bomb: the conversion of hydrogen to helium. Then even hotter stars fused helium into carbon, oxygen, and the rest of the periodic table.
Every atom on Earth was forged in an ancient star that completed its life more than four and a half billion years ago. Those ancient stars exploded, throwing debris back into interstellar gas. Our solar system condensed from interstellar clouds contaminated by the debris from earlier stars. So we are literally the ashes of long dead stars, or, if you are less romantic, we are the nuclear waste from fuel that made those ancient stars shine. On the basis of this hypothesis, we can understand why oxygen and carbon are common but gold and uranium are rare, and how they came to exist in our solar system.
Mastos: So your six numbers are setting the physical parameters for life to occur in the universe?
REES: We can understand how stars and planets formed, and how they came to contain all the basic elements necessary for life. So setting the scene for the origin of life is something we do understand better. Then biologists take over, and biology is a harder subject than physics and astronomy, because what makes things hard to understand is not how big they are but how complicated they are. As I said in one of my books, an insect is more complex than a star. A star is basically a large ball of gas held together by gravity, while even the smallest insect has layer upon layer of structure and is a far greater challenge to understand.
In a universe where the basic governing physical laws were different, these processes couldn't have happened. If gravity were too strong, then you couldn't have long-lived, stable stars, because gravity would crush everything. If the forces within the atomic nucleus were too strong, then hydrogen would not exist. If those nuclear forces were too weak, then only hydrogen would exist, and not the other elements.
So it does seem that there are various ways in which the laws of physics are fine-tuned, and the same is true of the universe itself. You could imagine a universe that expanded so fast that gravity could never pull together proto-galaxies or proto-stars. Or a universe that expanded so slowly, it collapsed before there'd been time for anything much to happen. You could imagine a universe that contained no atoms at all -- just dark matter and dark energy. So in order to provide the pre-conditions for any kind of life or complexity, our universe had to be set up and governed by rather special laws.
This leads to another mystery, a mystery that physicists address rather than biologists, which is the nature of the physical laws. Are there equations that can define those laws exactly, and give us the mass of the electron, or the strength of different forces? Or will we never have such a thing? Could it be that the strength of these forces is some kind of environmental accident?
One idea many of us are pursuing is a grander concept of the physical world. Over history we've gone from thinking of our solar system as being the center of the universe, to our galaxy being the center, to the present consensus that our big bang gave rise to zillions of galaxies. Some of us now think that perhaps we have to go a step further -- that the big bang wasn't the only one.
Mastos: There could be other universes...
REES: There could other universes separate from ours, other big bangs maybe separated by an extra-spatial dimension, or different in other ways. If that's the case, then it's possible that those different universes would be governed by somewhat different physical laws.
Some physicists believe this is true. If so, then the fine-tuning of our universe occasions no surprise. If there were not merely zillions of galaxies in the aftermath of our big bang, but there were actually zillions of other big bangs, each governed by different laws, then some would have laws with the capricious forms and basic number values to allow complex life and evolution. Most of the universes would be sterile or stillborn. In this grander context, there will still be basic laws of nature, but they'd be at a deeper level.
What we traditionally call the "laws of nature" -- the "laws" that determine the so-called "physical constants" -- could then be just parochial bylaws in our cosmic patch.
Britain's Astronomer Royal, Martin Rees , took time from his busy schedule to talk with Astrobiology Magazine's Chief Editor and Executive Producer, Helen Matsos. His three-part interview considers a broad range of alternative planetary futures, while highlighting today's changes in one of the oldest sciences, astronomy.
Martin Rees earned his degrees in mathematics and astronomy at the University of Cambridge , where he is currently professor of cosmology and astrophysics and Master of Trinity College. Director of the Institute of Astronomy at Cambridge, he has also been a professor at Sussex University. He has been Britain's Astronomer Royal since 1995. He has modeled quasars and has made important contributions to the theories of galaxy formation, galaxy clustering, and the origin of the cosmic background radiation.
His early study of the distribution of quasars helped discredit the steady state cosmological theory. He was one of the first to propose that enormous black holes power the quasars. He has investigated the anthropic principle, the idea that we find the universe the way it is because if it were much different we would not be here to examine it, and the question of whether ours is one of a multitude of "universes." He has written nine books . Through his public speaking and writing he has made the Universe a more familiar place for everyone
But an "infinite number of universes" is precisely what is not given; it is a speculation; an interesting one, but a speculation nonetheless. It's not a matter of us liking the laws we have. The point is we wouldn't be here to express our liking/appreciation if the ones we've got weren't precisely what they are.
Drake's equation is a joke.
The puddle will follow the second law of thermodynamics. Or it will be sent to bed without dinner.
> an "infinite number of universes" is precisely what is not given; it is a speculation
Yes, a specualtion... but one based not on wishful thinking, but as the result of theories that have been shown to be valid.
> The point is we wouldn't be here to express our liking/appreciation if the ones we've got weren't precisely what they are.
"We" probbaly wouldn't. But so what? If America wasn't here, "we" wouldn't be here either.
Basically... what makes you think that you are so special? What makes you think that the universe was set up just for *your* comfort? As opposed to thinking that you are just a natural function of this universe?
Sorry to be pedantic, but given an infinite set, something happening is guaranteed...
There are fundamental questions in all of these threads that few address.
Is the universe knowable?
If it is knowable from some perspective, is that absolute? Can not another observer from a different perspective come to a different conclusion?
Metaphysically, and I was spending alot of time yesterday morning thinking about this, these questions are almost paraphrase of another question:
Can new, heretofore unknown and nonexistent natural laws spontaneously come into existence?
I don't have many fans on these threads so I'll leave it at that.
Hi PatrickHenry. Surprised you posted this; the anthropic principle is basic to Intelligtent Design. This fine scientist makes no opinion about the requisite biological soup that we supposedly evolved from and leaves that to the biologists. It's a fair article, and basically he is shrugging his shoulders, saying "who knows?". Happy New Year. RIW
> given an infinite set, something happening is guaranteed...
Well, no. Consider the set of positive integers: 1,2,3,4,... all the way up. It is an infinite set. But what it *doesn't* have are things like 1.2345 and -4.
Another thing it has is a beginning (1), but no end. And no middle. Perhaps a good analogy for the universe: it had a definite beginning, but no end is in sight.
From the article:
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We don't really know the likelihood of life because the uncertainties in the Drake equation, which still are still very large, are the probabilities that life gets started given the right kind of initial soup.
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We have a pretty good grasp on the probabilities of abiogenesis for life like ours, and it ain't a small number. Something on the order of 10^100 against.
And, no, natural selection can't work on abiogenesis; it's pure chemistry, folks.
And I know that evolution supposedly doesn't cover the beginning of life, but the scientist in the article brought it up, not me.
Good story. I suspect that Rees' anomalous configuration could exemplify some aspect of the fine tuning issue, but I can't quite force it to the surface of my brain. And it would be inappropriate even if I could figure it out.
Thanks, I'll take a look. My son is a grad student in nuclear physics so its good to have things to talk about. I do understand the scientific method, the thing that bugs me a bit is the way hypotheses with a lot of unanswered questions get thrown around as fact. I'm not talking about this specific article. But the statement that a hypothesis answers many questions sounds like a fact, when it should have been stated the hypothesis "could" or "may" (or may not) answer a lot of questions.
Google up "WMAP" and "flatness". There was also a very good discussion of it in Max Tegmark's Scientific American article on parallel universes, available somewhere in here. Max calls it a "Level-1 Multiverse"; you can read much more on the page I linked.
In a nutshell, the argument goes like this: we measure that the spatial geometry of the universe is very flat, all the way out to the most distant quasars and galaxies. So the space extends beyond what we can see. Matter does, too: if there were no matter beyond, the gravitational forces on the distant quasars would not be balanced, and so they would not be receding, but would be drawn back towards the rest of the Hubble volume by the gravitational pull of all the stuff inside it--the stuff we see.
We know that the matter just beyond--heck, a good distance beyond--the quasars has (or rather, will) become (by 14 billion years after the Big Bang) stars and galaxies, because the physics there is not appreciably different from what it is here, and that's what matter does under these conditions. (Go far enough beyond, though, and who can say?)
Not by any stretch. An infinity of additional campaign stops wouldn't have helped John Kerry.
.....universe has laws we need . I would much rather like a universe with twice as much oxygen, think how happy everyone would be.
What makes you think that I think I'm "special?" Or that I think the universe was "set up" (i.e., designed????) for *my* comfort? Methinks you assume too much, orionblamblam. Here's an article I just love, from Max Tegmark: (I hope you like it, too.)
http://wintersteel.homestead.com/files/ShanaArticles/multiverse.pdf
FWIW, I'm a great fan of the Class IV multiverse....
> universe has laws we need
Yes, but we'd get by with slightly different laws and constants. How much different would life be if the speed of light was slower by 50 miles per hour? If Pi was different in the 45th decimal place?
This may seem like wild speculation to some, but it fits within the realm of science. Science is a process and part of that process is this type of speculation. There are questions about our universe that scientists are asking and, within the limits of our cuurent knowledge, the article above asks some very interesting questions and proposes answers based upon what we know. This is the first step in the scientific method - the formation of various hypotheses. The next step would be developing methods to test these hypotheses. That's why cosmolology is so theoretical. We have the math and logic to speculate how the universe may be structured, but experimental physics has to play catch up.
The same things were happening over a century ago in chemistry. There were many speculative models of matter that were proposed, such as the raisin bun model of matter. It fit with what was known at the time but further gains in knowledge made it obsolete. Then there was Bohr's model of atomic structure, then came quantum mechanics.
Over the course of time, science is like a lens that is changing to give better and better focus of our surroundings. The above speculation is an interpretation of that which is still slightly out of focus.
I like that one. What I now need to find is the Espresso Machine that pours coffy in the same shape as MY cup! ;-)
Gosh, and here Buggman was just denouncing the use of such qualifiers in post 9.
The problem you mention is real, but it's a problem of reportage rather than one of science. Scientists are reflexively careful to delineate what is known from what is unknown. If anything, the bias of scientists lies in the other direction, taking nothing as established. In particle physics, essentially all of the effort goes in to proposing (and searching for) exceptions to rules that are more firmly established than any rules in any other field of inquiry.
This is not an exaggeration: some decay experiments search for decay patterns that have not occurred once in a trillion trials...so far. The next round of experiments will search for even rarer decay patterns, that could only be expected once in a quadrillion trials. There's no point at which we will ever say, "well, that's enough. If it hasn't happened by now, it never will."
Damn. Where is that expresso machine? I obviously need it.
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