A Universe from Nothing: Why There Is Something Rather than Nothing

by Lawrence Krauss

But I wasn’t fully aware of how my choice of words might lead to the same kind of confusion that occurs whenever one says in public that Evolution is a theory.

9 of this book I mention a fact that I now want to introduce first here. Whenever one asks “Why?” in science, one actually means “How?”. “Why?” is not really a sensible question in science because it usually implies purpose

More important, however, we know our solar system is not unique, which Kepler and his era did not know.

no evidence of “purpose” in the distribution of planets in the universe.

So too, when we ask “Why is there something rather than nothing?” we really mean “How is there something rather than nothing?

This brings me to the second confusion engendered by my choice of words. There are many seeming “miracles” of nature that appear so daunting that many have given up trying to find an explanation of how we came to be and, instead, blame it all on God. But the question I really care about, and the one that science can actually address, is the question of how all the “stuff” in the universe could have come from no “stuff,” and how, if you wish, formlessness led to form. That is what seems so astounding and nonintuitive. It seems to violate everything we know about the world—in particular the fact that energy in its various forms, including mass, is conserved.

The fact that we need to refine what we mean by “common sense” in order to accommodate our understanding of nature is, to me, one of the most remarkable and liberating aspects of science.

Our modern conception of the universe is so foreign to what even scientists generally believed a mere century ago that it is a tribute to the power of the scientific method and the creativity and persistence of humans who want to understand it. That is worth celebrating.

Proposed almost fifty years ago to allow for consistency between theoretical predictions and experimental observations in elementary particle physics, the Higgs particle’s discovery caps one of the most remarkable intellectual adventures in human history—one that anyone interested in the progress of knowledge should at least be aware of—and makes even more remarkable the precarious accident that allowed our existence to form from nothing, the subject of this book. The discovery is further proof that the universe of our senses is just the tip of a vast, largely hidden cosmic iceberg and that seemingly empty space can provide the seeds for our existence.

Just fifty years ago, in spite of the great advances of physics in the previous half century, we understood only one of the four fundamental forces of nature—electromagnetism—as a fully consistent quantum theory.

Hidden in what seems like empty space—indeed, like nothing—appear to be the very elements that allow for our existence.

One of the most poetic facts I know about the universe is that essentially every atom in your body was once inside a star that exploded. Moreover, the atoms in your left hand probably came from a different star than did those in your right. We are all, literally, star children, and our bodies made of stardust.

Observations had determined that we live in an open universe, one that would therefore expand forever.

(Choose the high school carefully, however . . . a European one is a good bet.)

Amerikan okullarının rezilliğine dikkat çekiyor!

The CMBR is nothing less than the afterglow of the Big Bang. It provides another piece of direct evidence, in case any is needed, that the Big Bang really happened, because it allows us to look back directly and detect the nature of the very young, hot universe from which all the structures we see today later emerged.

About 1 percent of that static you saw on the television screen was radiation left over from the Big Bang.

Now, as I look out in the sky back further and further in time, I am looking at the universe as it was younger and younger, and also hotter and hotter, because it has been cooling ever since the Big Bang. If I look back far enough, to a time when the universe was about 300,000 years old, the temperature of the universe was about 3,000 degrees (Kelvin scale) above absolute zero. At this temperature the ambient radiation was so energetic that it was able to break apart the dominant atoms in the universe, hydrogen atoms, into their separate constituents, protons and electrons. Before this time, neutral matter did not exist.

It is therefore a prediction of the Big Bang picture of the universe that there should be radiation coming at me from all directions from that “last scattering surface.” Since the universe has expanded by a factor of about 1,000 since that time, the radiation has cooled on its way to us and is now approximately 3 degrees above absolute zero. And that is precisely the signal that the two hapless scientists found in New Jersey in 1965, and for whose discovery they were later awarded the Nobel Prize.

Infinity is not a pleasant quantity, however, at least as far as physicists are concerned, and we try to avoid it whenever possible.

The source of the infinity is easy to describe. When we consider all possible virtual particles that can appear, the Heisenberg Uncertainty Principle (which I remind you says that the uncertainty in the measured energy of a system is inversely proportional to the length of time over which you observe it) implies that particles carrying ever more energy can appear spontaneously out of nothing as long as they then disappear in ever-shorter times. In principle, particles can therefore carry almost infinite energy as long as they disappear in almost infinitesimally short times.

In the intervening decade, all the rest of the data from cosmology has continued to solidify the general concordance picture of a cockamamie, flat universe in which the dominant energy resides in empty space and in which everything we can see accounts for less than 1 percent of the total energy, with the matter we can’t see being composed mostly of some yet unknown, new type of elementary particles.

The origin and nature of dark energy is without a doubt the biggest mystery in fundamental physics today.

The false vacuum energy would behave just like that represented by a cosmological constant because it would act like an energy permeating empty space.

Special relativity says nothing can travel through space faster than the speed of light. But space itself can do whatever the heck it wants, at least in general relativity.

As I have described already, the laws of quantum mechanics imply that, on very small scales, for very short times, empty space can appear to be a boiling, bubbling brew of virtual particles and fields wildly fluctuating in magnitude. These “quantum fluctuations” may be important for determining the character of protons and atoms, but generally they are invisible on larger scales, which is one of the reasons why they appear so unnatural to us.

The pattern of density fluctuations that result after inflation—arising, I should stress, from the quantum fluctuations in otherwise empty space—turns out to be precisely in agreement with the observed pattern of cold spots and hot spots on large scales in the cosmic microwave background radiation. While consistency is not proof, of course, there is an increasing view among cosmologists that, once again, if it walks like a duck and looks like a duck and quacks like a duck, it is probably a duck.

Quantum fluctuations, which otherwise would have been completely invisible, get frozen by inflation and emerge afterward as density fluctuations that produce everything we can see! If we are all stardust, as I have written, it is also true, if inflation happened, that we all, literally, emerged from quantum nothingness.

At the present time only about 15 percent or so of all the observed helium in the universe could have been produced by stars in the time since the Big Bang—once again, a compelling bit of evidence that a Big Bang was required to produce what we see.

Indeed, whenever I’m asked about the near future of science or what the next big breakthrough will be, I always respond that if I knew, I would be working on it right now!

among any sufficiently large number of events, something unusual is bound to happen just by accident.

Our universe is so vast that, as I have emphasized, something that is not impossible is virtually guaranteed to occur somewhere within it.

A number of central ideas that drive much of the current activity in particle theory today appear to require a multiverse.

In the inflationary picture, during the phase when a huge energy temporarily dominates some region of the universe, this region begins to expand exponentially.

I want to stress that a multiverse is inevitable if inflation is eternal, and eternal inflation is by far the most likely possibility in most, if not all, inflationary scenarios.

Some theorists have estimated that there are perhaps 10500 different possible consistent four-dimensional universes that could result from a single ten-dimensional string theory.

On a slightly less facetious note, the Nobel Prize–winning physicist Frank Wilczek has suggested that string theorists have invented a new way of doing physics, reminiscent of a novel way of playing darts. First, one throws the dart against a blank wall, and then one goes to the wall and draws a bull’s-eye around where the dart landed.

The universe is the way it is, whether we like it or not.

this question too has been informed by science, like essentially all such philosophical questions.

For, after all, in science one achieves the greatest impact (and often the greatest headlines) not by going along with the herd, but by bucking against it.

Our observable universe is as close to being flat as we can measure. The Newtonian gravitational energy of galaxies moving along with the Hubble expansion is zero—like it or not.

First, I want to be clear about what kind of “nothing” I am discussing at the moment. This is the simplest version of nothing, namely empty space. For the moment, I will assume space exists, with nothing at all in it, and that the laws of physics also exist. Once again, I realize that in the revised versions of nothingness that those who wish to continually redefine the word so that no scientific definition is practical, this version of nothing doesn’t cut the mustard. However, I suspect that, at the times of Plato and Aquinas, when they pondered why there was something rather than nothing, empty space with nothing in it was probably a good approximation of what they were thinking about.

Empty space can have a non-zero energy associated with it, even in the absence of any matter or radiation.

when inflation ends, the energy stored in empty space gets turned into an energy of real particles and radiation, creating effectively the traceable beginning of our present Big Bang expansion.

small-density fluctuations in empty space due to the rules of quantum mechanics will later be responsible for all the structure we observe in the universe today.

Therefore, our observable universe can start out as a microscopically small region of space, which can be essentially empty, and still grow to enormous scales containing eventually lots of matter and radiation, all without costing a drop of energy, with enough matter and radiation to account for everything we see today!

It certainly seems sensible to imagine that a priori, matter cannot spontaneously arise from empty space, so that something, in this sense, cannot arise from nothing. But when we allow for the dynamics of gravity and quantum mechanics, we find that this commonsense notion is no longer true. This is the beauty of science, and it should not be threatening. Science simply forces us to revise what is sensible to accommodate the universe, rather than vice versa.

the observation that the universe is flat and that the local Newtonian gravitational energy is essentially zero today is strongly suggestive that our universe arose through a process like that of inflation, a process whereby the energy of empty space (nothing) gets converted into the energy of something, during a time when the universe is driven closer and closer to being essentially exactly flat on all observable scales.