http://www.newscientist.com/article/mg19826511.500-the-great-antimatter-mystery.html?full=true&print=true

The Great Antimatter Mysteryby Helen QUINN and Yossi NIR

New Scientist, 11 April 2008, #2651

It is lucky for us that the infant universe did not behave the way our best cosmic theories would have it. Nearly 14 billion years ago, the big bang forged equal amounts of matter and its nemesis, antimatter. These should have annihilated each other in bursts of pure radiation, leaving a universe filled with light. Instead, though, it is full of stars and planets and gas - something threw a cosmic spanner in the works. The stars and galaxies that light up the heavens would not exist today if matter had not won out over antimatter at some very early time in the evolution of the universe. How and when did this happen? Why is there something rather than nothing? These questions are at the root of our very existence, but as yet science has no clear answers.

That’s not to say we haven’t made progress. As in any good detective story physicists have picked up important clues, mainly by creating antimatter and studying what it does. Other evidence comes from neutrinos, those ghostly particles created in radioactive decays. These clues have provided two very promising lines of inquiry and thrown up some controversial results along the way. With the advent of new experiments there is a chance we will have answers very soon.

To create the universe we see today, a preference for matter must have arisen in the early universe. It only needed a minute imbalance, with as few as one extra particle of matter surviving for every 30 million antimatter particles.

“Ex nihilo, Nihilo Fit”, from Wikipedia, the free encyclopedia

The Latin phrase ex nihilo means “out of nothing”. It often appears in conjunction with the concept of creation, as in creatio ex nihilo, meaning "creation out of nothing". Due to the connotations of the phrase creatio ex nihilo, it often occurs in philosophical or creationistic arguments, as many Christians, Muslims and Jews believe that God created the universe from nothing. This contrasts with creatio ex materia (creation out of eternally preexistent matter) and with creatio ex deo (creation out of the being of God).

A number of philosophers[who?] in ancient times attained a concept of God as the supreme ruler of the world, but did not develop a concept of God as the absolute cause of all finite existence. Before the biblical idea of creation arose, myths envisioned the world as preexisting matter acted upon by a god or gods who reworked this material into the present world. The Hebrew tradition and the religious thought that developed out of its world-view apparently originated the formulation of “ex nihilo creation”.[1]

Son, look upon heaven and earth, and all that is in them: and consider that God made them out of nothing.(2 Maccabees 7:28, 100 BC)

Ex nihilo when used outside of a religious context also refers to something coming from nothing. For example, in a conversation, one might raise a topic "ex nihilo" if it bears no relation to the previous topic of discussion. The term also has specific meaning in military and computer-science contexts

That couldn’t occur by chance, though. Even this tiny excess is too big to occur as a random fluctuation in the hot, early universe. Nor is the universe likely to have started out with such a finely tuned imbalance (see “Was the universe born lopsided?”). What’s more, it definitely doesn’t seem to be hiding pockets of antimatter today (see “Where are all the anti-galaxies?”). So how the excess arose during the history of the universe must be encoded somewhere in the basic laws of physics. How the excess of matter arose must be encoded in the basic laws of physics

Russian physicist Andrei Sakharov was the first to take on this puzzle in 1967. He showed that for there to be more matter than antimatter, three conditions are needed. First, Sakharov argued that no conservation law can forbid reactions which effectively change the balance between particles and antiparticles. This was a bold claim, as such reactions have never been seen experimentally.

To make this possible, Sakharov pointed out that the laws of physics must be slightly different for matter and antimatter, as had been revealed in experiments three years earlier with particles called long-lived kaons. These showed that the weak force, which is best known for its role in radioactive decay, does not act equally on quarks and antiquarks.

Finally, there must have been a period early in the universe’s history when the various reactions going on between the different particles and antiparticles and radiation in the primordial plasma started to take place at different rates. This can only happen if they are, for some reason, not in thermal equilibrium. Without these conditions the universe would never have evolved from its initial state of having equal amounts of matter and antimatter to its present highly unbalanced state. Fast forward to today and Sakharov’s conditions remain as relevant as ever. In the intervening years, they have acted as an important guide for our theories of the early universe.

The standard models of cosmology and particle physics suggest that when the universe was less than 10 -12 seconds old, particles and their interactions were very different from what they are today. All the fundamental particles were massless and the weak interactions between them were more active. As the universe expanded and cooled, it switched to a more favourable, lower-energy state. Here the particles gained mass and the weak interactions became less active.

This cooler state started off as a tiny bubble that expanded rapidly throughout the early universe. As it did so, the bubble’s surface upset the thermal equilibrium of the universe and interacted with the massless particles and antiparticles. Some of them passed through and ended up inside the bubble, while others bounced off.

Interactions at the bubble wall made it more likely for a quark to break through the bubble wall than an antiquark, so inside the bubble there was an excess of quarks, while the antiquarks outside were removed by the more active processes. Today, the bubble is the size of the universe, and because we live inside it we see the excess of quarks as a dominance of matter over antimatter.

It’s a lovely, neat picture. The only problem is, it doesn’t give the right numbers. When we use the standard model to calculate the amount of matter and antimatter, we get far too small an excess. This is one of the reasons why particle physicists think the standard model is incomplete. Is there a way to fix it?

Perhaps. One of the most promising extensions of the standard model is supersymmetry, which demands many as-yet-unknown particles beyond the reach of existing experiments. As well as explaining the antimatter imbalance, supersymmetry might tell us about the nature of the dark matter that accounts for 90 per cent of the matter in the universe, and why gravity is so puny compared with the other forces.

While theorists embrace supersymmetry, so far we have found no evidence for it in experiments. However, hints of a process that does not fit the standard picture recently came to light. Last month, a team of physicists in Italy, France and Switzerland known as the UTfit collaboration analysed particles called Bs mesons, created in two experiments at the Tevatron accelerator at Fermilab in Batavia, Illinois. Made of a ‘bottom’ antiquark and a ‘strange’ quark, Bs mesons are unstable and decay via the weak force into particles made of lighter quarks and antiquarks.

The UTfit collaboration argues that when they combine all the B s meson results, they find a small discrepancy that could be evidence for a new interaction outside the standard model that acts differently on quarks and antiquarks, and might possibly be a reason for the excess of quarks in our universe (New Scientist, 18 March, p 10).

It is far too early to say whether this a first hint of supersymmetry. More observations are needed to confirm the UTfit group has indeed found something amiss, and we will still need to discover some supersymmetric particles to provide proof. They might turn up at the Large Hadron Collider (LHC), the world’s most powerful accelerator, due to switch on later this year at the CERN laboratory near Geneva, Switzerland. Assuming supersymmetric particles are detected there, we will be able to measure their masses and some of their interactions, but even that won’t be enough. Additional experiments will be needed to tell if supersymmetry generated the right excess of matter when the universe was about 10-11 seconds old.

Other planned experiments to study supersymmetry in detail include the International Linear Collider, which will smash electrons and positrons together (New Scientist, 25 August 2006, p 36) and an experiment to study the electromagnetic properties of the neutron.

Neutrinos to the rescueAn alternative way to explain the mystery of the missing antimatter emerged in the mid-1980s. Japanese physicists Masataka Fukugita and Tsutomu Yanagida showed how the matter-antimatter imbalance might have arisen in a scenario known as leptogenesis. If this idea is correct, we owe our existence to neutrinos. If certain scenarios of the early universe are correct, we owe our existence to neutrinos.

Neutrinos are the most elusive of all particles in the standard model, and were long thought to be massless. However, a series of beautiful experiments carried out over the past 40 years in the US, Japan, Canada and elsewhere have established that the standard model is wrong: neutrinos do have mass, albeit a very tiny one.

This means they could have played a role in the antimatter imbalance. Adding neutrino masses into the theoretical picture means adjusting the standard model, and the simplest way to do this is to assume the existence of a new type of particle, a kind of very heavy neutrino called a singlet neutrino. These neutrinos are unlike any other particle we know because they do not interact with other particles via the usual forces in nature, so they are probably extremely difficult to detect. Like all fundamental particles, they would have been produced in appreciable quantities in the very early universe. But their interactions would have been too feeble to keep them in thermal equilibrium with the rest of the primordial plasma, in keeping with one of Sakharov’s three conditions.

According to the leptogenesis scenario, singlet neutrinos travel freely across the universe until they decay into either neutrinos or antineutrinos. Crucially, according to the theory more antineutrinos can be produced than neutrinos, once again in line with Sakharov’s ideas.

Leptogenesis therefore leaves the very early universe with an excess of antineutrinos. At this stage, the standard model predicts that certain reactions could occur in the very high-temperature conditions to convert antineutrinos into matter particles, eventually producing protons and neutrons and leaving the universe devoid of antimatter.

Testing leptogenesis will be tricky, as there is unlikely to be a way to produce singlet neutrinos in the lab and measure their decays. They are likely to be much too heavy and their interactions are dramatically too feeble for us to be able to do that. However, there are ways to test whether the idea is at least possible.

Leptogenesis predicts that the singlet neutrinos can interact with normal neutrinos by swapping Higgs particles - the particles that are thought to give mass to all matter and antimatter particles. From what we know about normal neutrinos and the Higgs particle, we can make inferences about singlet neutrinos. So far, their features appear to match what is needed for leptogenesis, and this provides some circumstantial evidence in support of the idea.

Another test concerns a property called the ‘lepton number’. Electrons and neutrinos belong to the family of particles called leptons and are assigned a lepton number of 1. Their antimatter counterparts have a value of -1. In all the reactions we have measured so far, the lepton number before and after the reaction has stayed the same.

However, the leptogenesis theory predicts that adding singlet neutrinos to the mix makes it possible for regular neutrinos to change into antineutrinos and vice versa. So it fails to conserve lepton number. Particle physicists regularly check their experiments for signs of lepton number violation because this would directly prove Sakharov’s first condition, that there is no conservation law in nature protecting the matter-antimatter balance.

So far, only one group claims to have seen a reaction that violates lepton conservation. Hans Klapdor-Kleingrothaus at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, says that his group first saw lepton violation in 2001, in germanium-76 nuclei (New Scientist, 4 September 2004, p 37).

They claim to have observed a reaction called neutrinoless double beta decay. In normal beta decay, a neutron inside a nucleus spontaneously transforms into a proton, producing an electron and an antineutrino in the process. The lepton number is 0 before and afterwards. A few rare radioactive elements go one better and undergo double beta decay, where two neutrons inside the same nucleus change at the same time, spitting out two electrons and two antineutrinos. In the neutrinoless version of double beta decay, there are no antineutrinos, only two electrons. Here the lepton number changes from 0 before the reaction to 2 afterwards.

The Heidelberg group’s findings are controversial, though, and while several teams of physicists are attempting to replicate the experiment, none has yet succeeded. Still, many physicists are convinced that leptogenesis is the prime suspect for solving the antimatter puzzle, and so the search for lepton number violation goes on.

For now the mystery has at least two possible answers. It is down to experiments to choose between them, or even eliminate both and send theorists back to the drawing board. If supersymmetry provides the answer we will eventually know it. But if leptogenesis is the right answer, then it is likely to remain forever a plausible yet unproven aspect of cosmology. Like it or not, the universe may never reveal all its secrets.

Cosmology - Keep up with the latest ideas in our special report.Quantum World - Learn more about a weird world in our comprehensive special report.

Was the cosmos born lopsided?How do we know that the universe did not just start out with an imbalance of matter and antimatter? The more we understand the early history of the universe the less it seems that this is possible. First, if the asymmetry between matter and antimatter had been an initial condition, it would have been a very peculiar one. By studying the amounts of light elements forged in the very early universe, we can work out that there must have been 30,000,001 matter particles for every 30,000,000 antimatter particles. It seems very unlikely that such a fine-tuned situation appeared accidentally.

Even if there had been an initial imbalance, it would have been erased in a period of rapid expansion called inflation that diluted the initial densities to minuscule proportions. There is growing evidence from the cosmic microwave background that inflation did indeed take place. It is almost certain that the excess of matter was generated after inflation.

Where are all the anti-galaxies?We have good reasons to think that all the structures in the observable universe are made from matter and not antimatter. For a start, space probes have touched down on the moon and other planets without annihilating in a burst of radiation. Intergalactic space is flooded by particles blasted out by active galaxies; any antimatter galaxies around would radiate antiparticles which would annihilate on meeting these particles, creating glowing surfaces with characteristic energies. We don’t see any of these as far out as we can possibly observe.

It is also extremely unlikely that the hot, dense mixture in the early universe sorted itself out into a few equally huge regions of matter and antimatter. You would have to have very different laws of physics for matter and antimatter to unmix like this. We know the laws are in fact very similar, so we conclude that it is matter which makes up the galaxies in our entire universe.

Helen Quinn is professor of physics at the Stanford Linear Accelerator Center at Stanford University, California. Yossi Nir is professor of physics at the Weizmann Institute of Science in Rehovot, Israel. Their latest book is The Mystery of the Missing Antimatter (Princeton)

For similar stories, visit the Cosmology , Quantum World and The Large Hadron Collider Topic Guides

From issue 2651 of New Scientist magazine, page 26-29. Subscribe and get 4 free issues. Browse past issues of New Scientist magazine

http://www.newscientist.com/article/dn13454-qa-2008-templeton-prize-winner.html?full=true&print=true

Q&A: 2008 Templeton Prize winner12 March 2008 by Amanda GEFTER

Cosmologist and Catholic priest Michael HELLER

(Image: Templeton Foundation)

At £820,000, the Templeton Prize for Progress toward Research or Discoveries about Spiritual Realities is the biggest science prize around - and one of the most controversial. This year’s winner is Michael Heller, a Polish cosmologist and Catholic priest, who is being recognised for his work on whether the universe needs a cause.

Amanda Gefter asked him how he manages to unite his religious beliefs with his research.

What does this prize mean to you?I feel very happy, a little surprised and a little out of tune because it somehow interferes with what I love best: quiet work in science and philosophy. On the other hand I appreciate the prize because it opens new possibilities for me in the fields of science and religion.

Why is it so important to you to combine these two fields?My father used to say that it is important to combine science and religion because these are the two most important activities for the future of humanity. Science gives us knowledge of the world and religion gives us meaning. Living in the Communist regime was another motive for me because Communist propaganda was strongly anti-religious in a brutal way. Their arguments were naïve but quite efficient so when I was studying physics and philosophy in Poland I also studied Marxist philosophy very carefully because I wanted to know the arguments.

What do you make of the current debate between science and religion, in which the two are often presented as mutually exclusive?Everything depends on your concept of rationality. Science is a model of rationality. The question is whether the limits of rationality coincide with limits of the scientific method. If they do, then there is no place for religion or theology because everything outside of the scientific method is automatically irrational. On the other hand, if you agree that they do not coincide then there is a place for rational religious belief. If you look at the recent history of science and philosophy, you can see that the dominating philosophy in western countries was positivistic, it said that the scientific method is identical with rationality and that what’s beyond the scientific method is beyond rationality. Nowadays very few philosophers agree with this; we are more pluralistic.

In your statement today you said: “Things thought through by God should be identified with mathematical structures interpreted as structures of the world.” Does that mean that you see mathematics as the language of God?In a word, yes. One of my heroes is Leibniz, the great philosopher of the 17th century. In the margin of his work entitled Dialogus there is a short handwritten remark in Latin that says, “When God calculates and thinks things through, the world is made.” My philosophy is encapsulated in that.

The Templeton Foundation has said that you “initiated what can be justly termed the theology of science”. What is the theology of science?Science is about investigating the world. The method of physics is selective - some aspects of the world are investigated by physics and some are not. Anything that cannot be put into mathematical structures is transparent to the methods of physics. But theology and philosophy can look at the same universe with different eyes; they can contemplate other aspects of the world, such as values. In my view theology of science should take into account that not everything in the world can be investigated by science.

You have said that proponents of intelligent design are committing a grave theological error. Can you explain that?The standard theory of evolution ascribes a lot of results to chance, whereas adherents of intelligent design say that instead everything should be planned by God. What is a random event? It is something which is of low probability which nevertheless happens. But in order to know whether something is of low or high probability you have to use the calculus of probability, a non-random mathematical structure. So chance events are still part of God’s mind. I don’t see any conflict between chance events and God’s planning of the universe.

You have done a lot of research into whether the universe requires a cause. Have you come up with an answer?I recently wrote a book on this called The Ultimate Explanations of the Universe. Cause and effect is one of the most important explanations in the sciences. For any physical process you can always discover a sequence of states such that a preceding state is a cause for a following state which is its effect, and there is always a physical law which describes how this process develops. If you ask about the cause of the universe you’re really asking, what is the cause of physical laws? Then you’re back to Leibniz. He asked, why is there something rather than nothing? My answer is that indeed the universe needs a cause but this cause is unlike any other cause investigated by science because it is the cause of existence itself.

What are you working on these days?I am working on a fundamental problem in physics: unifying general relativity [which describes the large-scale effects of gravity], and quantum mechanics [which applies to sub-atomic scales]. With some colleagues from Warsaw I have created a model based on noncommutative geometry, which is an extremely interesting new branch of mathematics. In general relativity, spacetime is modeled as a smooth manifold [or sheet] - that’s ordinary commutative geometry. But there are other algebras that are not commutative. In spacetimes that contain a singularity the manifold breaks down, so you can’t use ordinary geometry. Our fundamental result is that at the smallest scale the geometry of space is noncommutative and nonlocal and it is probabilistic. When you describe the space probabilistically, singularities turn out to occupy a set of measure zero, which essentially means that singularities don’t exist at that level. They only appear at the macroscopic level as a kind of construct.

Some scientists have argued taking money from the Templeton Foundation - which assumes the existence of a creator - can undermine the integrity of scientific research. How do you respond to that?I can only speak for myself. I never worked with the view of obtaining some reward from Templeton or anyone else. It is very welcome, but it has not undermined my scientific integrity. On the other hand you must take into account that there are very powerful institutions that pay for research at the other end of this story, for instance during our Communist regime in Eastern countries the state invested a lot of money into research to support atheistic propaganda.

What will you do with the money?Even before I knew about the prize my colleagues in Krakow and I had plans to create an institute that would combine research in the fields of science, philosophy and theology. Our slogan is: philosophy in science, rather than philosophy of science, which is a well-established academic discipline. Some big philosophical issues are now inside science. For instance, concepts of time and space or determinism and causality, they were once philosophical concepts but are now essential issues in science. We decided to create an institute joining two universities in Krakow, Jagiellonian University and the Pontifical Academy of Theology. It will be called the Copernicus Centre. I will give all of my money from Templeton to this centre.

Michael Heller is a professor at the Pontifical Academy of Theology in Krakow and adjunct scholar at the Vatican Astronomical Observatory.

http://www.newscientist.com/article/mg20026832.100-the-free-lunch-that-made-our-universe.html

The Free Lunch That Made Our UniverseLawrence Krauss

25 November 2008, #2683

Twice in the past week I have been confronted in debates with the question that Thomas Aquinas and others have used in a theological context: “Why is there something rather than nothing?”

A timeline of the universe’s expansion since the big bang (Image: NASA)

I don’t want to dwell on whether this justifies the existence of God. Rather, I’d like to point out that physics has largely answered this question, at least if it is reframed as “how” rather than “why”.

A three-dimensional space can be geometrically open, closed or “flat”, and my scientific career was launched largely by a quest to show whether the universe we inhabit is the last of these. At the time, that meant working out how much dark matter there is, because Einstein’s theory of general relativity tells us that the

universe’s geometry depends on the mass and energy within it. We thought too little dark matter would produce an open universe, which would expand forever. Too much would give a closed universe, destined to collapse. A flat universe would be just between the two: its expansion would slow to a halt. Astronomers had yet to demonstrate that there was enough dark matter to stop the universe expanding forever, but we theorists were confident that our universe was flat.

Key to this was the notion of inflation, introduced by physicist Alan Guth to explain several cosmological puzzles, including that the universe appeared close to flat even after 14 billion years of expansion. A flat universe is like the top of a hill. If you are a little away from it - a bit open or a bit closed - the expansion of the universe soon drives you far away from this value, just as a ball that is a short distance from a hilltop will roll down to the bottom. Inflation, on the other hand, drives the universe towards flatness - just as blowing up a ball reduces the curvature of its surface.

But as Guth emphasised, there is another reason for favouring a flat universe: it is fundamentally beautiful. In a flat universe, the total gravitational energy is precisely zero.

A zero-energy universe may sound strange, but it relates to an idea taught in high school physics. A ball thrown up in the air has two forms of energy: kinetic and potential. If the sense of the kinetic energy is taken as positive, the potential energy, due to the gravitational pull of the Earth, is negative. If the positive portion of the energy beats the negative portion, the ball will escape from Earth. If the negative energy is greater, it will return. If the total energy is precisely zero the ball will barely escape - slowing to a stop when it is infinitely far away.

In terms of general relativity, the curvature of our expanding universe is related to the total gravitational energy of the objects being carried along with its expansion. In a flat universe, the total energy is zero. So a flat universe could have arisen from nothing. One can trade off the positive energy of particles for the negative energy of gravity and move from a situation in which there are no particles to one with a lot. As Guth put it: “There is such a thing as a free lunch!”

In recent years astronomers have discovered that we do seem to live in a flat universe, although we were wrong about how this comes about. Dark energy, not dark matter, appears to dominate, and it turns out that the strange nature of this stuff means that the geometry of the universe no longer determines its future.

We turned out to be wrong about how a flat universe comes about.

The key point, however, is that with zero total energy, Aquinas’s puzzle is resolvable. And once the energy fluctuations of quantum mechanics are thrown into the mix, the idea of something arising from nothing can become not just possible, but necessary.

Purists will argue that this begs the question of how the physical laws that make it all possible arose. Nevertheless, science has once again altered the playing field for such metaphysical speculations in a dramatic and beautiful way.

From issue 2683 of New Scientist magazine, page 53. Subscribe and get 4 free issues.

Forum : On Creating Something From NothingDavid Darling

New Scientist, 14 September 1996, #2047.

It’s the simple questions that usually tax science the most. For instance, why should there be something instead of nothing? The Universe is so outrageously enormous and elaborate. Why did it, or God if you prefer, go to all the bother?

Yes, I know that if the Universe was not more or less the way it is then there would be no one to reflect on such problems. But that is a comment, not an explanation. The fact is, nothing could be simpler than nothing so why is there something instead?

Science has started delving into the minutiae of genesis. No one bats an eyelid these days when cosmologists talk about what conditions might have been like around one ten million trillionth of a second after the moment of creation. And once we have got the tricky business of linking gravitation with quantum mechanics sorted out, then maybe we can push things right back to the very first instant of all.

Well, I’ve read the party manifesto on this and I didn’t buy it. I can go along with the quantum foam stuff, the good news (for once) about inflation, the quark soup and so on. That’s fine. I may not be able to imagine it who can? But, as far as I am concerned, the fact that the Universe was an incredibly weird place 10-43 seconds after “ time zero” is no big deal. What is a big deal the biggest deal of all is how you get something out of nothing.

Don’t let the cosmologists try to kid you on this one. They have not got a clue either despite the fact that they are doing a pretty good job of convincing themselves and others that this is really not a problem. “In the beginning,” they will say, “there was nothing no time, space, matter or energy. Then there was a quantum fluctuation from which ...”

Whoa! Stop right there. You see what I mean? First there is nothing, then there is something. And the cosmologists try to bridge the two with a quantum flutter, a tremor of uncertainty that sparks it all off. Then they are away and before you know it, they have pulled a hundred billion galaxies out of their quantum hats.

I don’t have a problem with this scenario from the quantum fluctuation onward. Why shouldn’t human beings build a theory of how the Universe evolved from a simple to a complex state. But there is a very real problem in explaining how it got started in the first place. You cannot fudge this by appealing to quantum mechanics. Either there is nothing to begin with, in which case there is no quantum vacuum, no pre-geometric dust, no time in which anything can happen, no physical laws that can effect a change from nothingness into somethingness; or there is something, in which case that needs explaining.

One of the most specious analogies that cosmologists have come up with is between the origin of the Universe and the North Pole. Just as there is nothing north of the North Pole, so there was nothing before the Big Bang. Voilà! We are supposed to be convinced by that, especially since it was Stephen Hawking who dreamt it up. But it will not do. The Earth did not grow from its North Pole. There was not ever a disembodied point from which the material of the planet sprang. The North Pole only exists because the Earth exists not the other way around.

It’s the same with neurologists who are peering into the brain to see how consciousness comes about. I do not have a problem with being told how memory works, how we parse sentences, how the visual cortex handles images. I can believe that we might come to understand the ins and outs of our grey matter almost as well as we can follow the operations of a sophisticated computer. But I draw the line at believing that this knowledge will advance our understanding of why we are conscious one jot. Why shouldn’t the brain do everything it does and still be completely unaware? Why shouldn’t it just process information and trigger survival responses without going to the trouble of generating consciousness? You only have to read the musings of Daniel Dennett, Roger Penrose, Francis Crick and others to appreciate that we are discovering everything about the brain except why it is conscious.

No, I’m sorry, I may not have been born in Yorkshire but I’m a firm believer that you cannot get owt for nowt. Not a Universe from a nothing-verse, nor consciousness from a thinking brain. I suspect that mainstream science may go on for a few more years before it bumps so hard against these problems that it is forced to recognise that something is wrong. And then? Let me guess: if you cannot get something for nothing then that must mean there has always been something. Hmmm. And if the brain doesn’t produce consciousness ... well, no, that is just too crazy isn’t it?

David Darling is an astronomer and author of After Life (Fourth Estate) and Zen Physics (HarperCollins).

A Something-For-Nothing UniverseJohn Hastings Whittlesey, Cambridgeshire, UK

New Scientist, 03 December 2008 #2685.

Lawrence Krauss has missed the point, in at least two ways, in his response to the question: “Why is there something rather than nothing?” (22 November, p 53). If the universe is flat, and the total energy of a flat universe is zero, all that tells us is that no energy input was required to create the universe. The universe could have been created out of no matter/energy. It does not tell us, however, how the universe got started.

The question of the theologian Thomas Aquinas can be rephrased along the lines of: “If there was once nothing, really nothing, not even the quantum vacuum, then how is it possible for something/anything to have got started?” The quantum vacuum is not nothing, and it is not zero energy; it is simply the lowest possible energy state in our universe.

The corollary to Aquinas’s question is: “Is there an infinite regression of causes ‘behind’ our universe, or is there a stopping point, a ‘first cause’ or a ‘brute fact’, something that simply exists of itself, uncaused?” Is the quantum vacuum the thing that simply exists and brought our universe into existence, or is there something else that brought the quantum vacuum into existence, and, if there is, how many more layers of causation are there?

A Something-For-Nothing Universe - ForumTim Wilkinson , Houghton-le-Spring, County Durham, UK

New Scientist, 10 December 2008, #2686.

Lawrence Krauss is vastly oversimplifying when he names the theologian Thomas Aquinas as the architect of the question “Why is there something rather than nothing?” (22 November, p 53). Aquinas was in fact concerned with the so-called cosmological argument: “god must exist, since god must have been the first cause”. He did not originate this argument either, but he greatly developed it and set out three different versions in great detail as three of his famous “ five ways” in Summa Theologica (1265-1274).

While Aquinas was explicitly trying to show that god must exist, the “why something rather than nothing” question is perfectly valid and interesting, not to say difficult, even in a godless universe such as the one in which we happen to live. Many philosophical heavyweights have referred to it as the most fundamental question in the history of philosophy, and physicists are welcome to agree.

The observation that the universe may be flat and hence its total energy zero is certainly fascinating and helps avoid a clash between the appearance of the universe in the first place and the first law of thermodynamics, although until the nature of dark energy is much better understood it is perhaps a little premature to declare that particular conundrum finally resolved.

As for Aquinas, nothing as complicated as the curvature of the universe is required to refute the cosmological argument, which is so inherently shaky that the slightest logical nudge brings it crashing down. “What caused god?” is the devastating objection that theologians have conspicuously failed to answer despite centuries of mental gymnastics with infinite regress and necessary-versus-contingent beings. The cosmological argument simply contradicts itself and should be allowed to rest in peace (though I somehow doubt that it will be). The question “why is there something rather than nothing?” is very much alive and kicking.

A Something-For-Nothing UniverseW. S. K. (Scott) Cameron, Dept of Philosophy, Loyola Marymount University, Los Angeles, CA, US

New Scientist, 10 December 2008, #2686.

Addressing Aquinas’s query, Lawrence Krauss argues that a universe whose total gravitational energy is zero answers this question, “at least if it is reframed as ‘how’ rather than ‘why’ ”. Unfortunately, Krauss misunderstands Aquinas, who insists on distinguishing the question ‘how’ from the metaphysically essential question ‘why’ - a question that remains unanswered by the physical evidence, whatever it may be.

Imagine three firms, each of which starts up, runs for a while, and then folds.

Forensic accountants later discover that one firm ran profitably under its founder but sold assets and folded for lack of an heir; another sputtered along before foundering under debt; and a third ran in an orderly way, balancing its books all through its waxing and waning.

Like the zero-energy universe, the third firm’s accounting is the most elegant, since we need not explain the capital or debt left at the end. But the universe’s elegant balance of energy no more explains why it came into being than the elegantly balanced books explains why the firm came into being.

Aquinas’s point (against Aristotle) was that without a Creator, the question ‘why’ was unanswerable; and he took that as a liability of Aristotle’s Creator-less eternal universe. But Aquinas was fair in recognising that one could just ignore the question. Krauss, in contrast, suggests that a “something-for-nothing” universe may be “not just possible, but necessary” only by misconstruing Aquinas’s point.