The Big Bang marking the beginning of the universe is amazing when one reflects on the fact that a state of "infinite density" is synonymous to "nothing." There can be no object that possesses infinite density, for if it had any size at all it could still be even more dense. Therefore, as Cambridge astronomer Fred Hoyle points out, the Big Bang Theory requires the creation of matter from nothing. This is because as one goes back in time, one reaches a point at which, in Hoyle's words, the universe was "shrunk down to nothing at all."

I recently was told by some physicists whom I had the chance to interview for a paper that the standard big bang model of the universe does not include a singularity anymore. That may have been the case twenty five years ago, they said, but nowadays physicists say that the big bang extends only back to Planck time. Can you PLEASE clarify the confusion I’m having on this?

God bless,

Glenn


Dr. Craig responds:

I’m just in the process of wrapping up an article on the kalam cosmological argument co-authored with James Sinclair for a forthcoming volume with Blackwell entitled Companion to Natural Theology. Jim is writing the section on the empirical evidence of astrophysical cosmology for the beginning of the universe. He does a marvelous job of summarizing the current state of the field, a preview of which I’ll give you here.

First, though, in answer to your question, the standard Big Bang model includes an initial singularity. The model cannot lose that feature and remain the same model. So there’s no question of the standard model’s not including a singularity anymore. Rather what the physicists you interviewed meant is that the standard model is no longer the prevailing view today. Their claim is that while the standard model was the accepted view 25 years ago, that is no longer the case today.

Now in one sense that’s true. The standard Big Bang model needs to be modified in various ways. For example, the model is based on Einstein’s General Theory of Relativity. But Einstein’s theory breaks down when space is shrunk down to sub-atomic proportions. We’ll need to introduce quantum physics at that point, and no one is sure how this is to be done. That’s what your physicists meant when they said that the Big Bang extends back only as far as the Planck time. (That, by the way, is no new realization; everyone always knew that General Relativity breaks down by that point.) Moreover, the expansion of the universe is probably not constant, as in the standard model. It’s probably accelerating and may have had a brief moment of super-rapid, or inflationary, expansion in the past.

But none of these adjustments need affect the fundamental prediction of the standard model of the absolute beginning of the universe.

Indeed, Jim’s survey of contemporary cosmology reinforces just how robust the standard model’s prediction of an absolute beginning continues to be. He considers three broad research programs being currently pursued based on possible exceptions to the Hawking-Penrose singularity theorems, which support the standard model’s prediction of an initial cosmological singularity. These are (1) Closed Timelike Curves, (2) Violation of the Strong Energy Condition (Eternal Inflation), and (3) Falsity of General Relativity (Quantum Gravity). The first of these postulates an exotic spacetime which features circular time in the past and so is not taken very seriously by the vast majority of cosmologists. The real work has been on the other two alternatives.

With respect to the alternative of Eternal Inflation, it was suggested by some theorists during the 1980s that perhaps the inflationary expansion of the universe was not confined to a brief period early in the history of the universe but is eternal in the past, each inflating region being the product of a prior inflating region. Although such models were hotly debated, something of a watershed appears to have been reached in 2003, when three leading cosmologists, Arvin Borde, Alan Guth, and Alexander Vilenkin, were able to prove that any universe which has, on average, been expanding throughout its history cannot be infinite in the past but must have a past space-time boundary.

What makes their proof so powerful is that it holds regardless of the physical description of the universe prior to the Planck time. Because we can’t yet provide a physical description of the very early universe, this brief moment has been fertile ground for speculations. (One scientist has compared it to the regions on ancient maps labeled “Here there be dragons!”—it can be filled with all sorts of fantasies.) But the Borde-Guth-Vilenkin theorem is independent of any physical description of that moment. Their theorem implies that even if our universe is just a tiny part of a so-called “multiverse” composed of many universes, the multiverse must have an absolute beginning.

Alexander Vilenkin is Professor of Physics and Director of the Institute of Cosmology at Tufts University. A theoretical physicist who has been working in the field of cosmology for 25 years, Vilenkin has written over 150 papers and is responsible for introducing the ideas of eternal inflation and quantum creation of the universe from nothing.

Vilenkin is blunt about the implications:

It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man. With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape, they have to face the problem of a cosmic beginning (Many Worlds in One [New York: Hill and Wang, 2006], p.176).

Some current cosmological speculation is based upon attempts to craft models based upon possible exceptions to the Borde-Guth-Vilenkin condition that the universe has on average been in a state of cosmic expansion. In his article Jim provides the following chart of possibilities:

The first case involves an infinite contraction prior to the singularity, followed by our current expansion. The second case postulates an unstable initial state followed by an inflationary expansion. The third case imagines a contraction followed by a super-expansion fueled by ‘dark’ energy, with the universe breaking into a multiverse. The fourth case postulates two mirror-image, inflationary expansions, where the arrows of time point away from the cosmological singularity. Jim shows that these highly speculative models are all either in contradiction to observational cosmology or else wind up implying the very beginning of the universe they sought to avert.

The other alternative to the Hawking-Penrose theorems that has been vigorously pursued is Quantum Gravity models. Jim provides the following chart of such models:

The first class of models postulates an eternal vacuum space in which our universe originates via a quantum fluctuation. It was found that these models could not avoid the beginning of the vacuum space itself and so implied the absolute beginning of spacetime. These models did not outlive the early 1980s.

The second class, string theoretical models, have been all the rage lately. They are based upon an alternative to the standard model of particle physics which construes the building blocks of matter to be, not pointlike particles, but one dimensional strings of energy. Jim discusses three types of string cosmological models:

The first of these string cosmologies, Ekpyrotic cyclic models, is subject to the Borde-Guth-Vilenkin theorem and so is admitted to involve a beginning of the universe. The second group, Pre-Big Bang models, cannot be extended into the infinite past if they are taken to be realistic descriptions of the universe. The third group, the string landscape models, feature the popular multiverse scenario. They are also subject to the Borde-Guth-Vilenkin theorem and so imply a beginning of the universe. Thus, string cosmological models do not serve to avert the prediction of the standard model that the universe began to exist.

The third class of Quantum Gravity models, Loop Quantum Gravity theories, features versions of a cyclical universe, expanding and contracting. These models do not require an eternal past, and trying to extend them to past infinity is hard to square with the Second Law of Thermodynamics and seems to be ruled out by the accumulation of dark energy, which would in time bring an end to the cycling behavior.

Finally, fourth, the Semi-classical Quantum Gravity models include the famous Hartle-Hawking model and Vilenkin’s own theory:

These models feature an absolute beginning of the universe, even if the universe does not come into being at a singular point. Thus, Quantum Gravity models no more avoid the universe’s beginning than do purported Eternal Inflationary models.

In sum, I think you can see how misleading the physicists’ statements to you were. The prediction of the standard model that the universe began to exist remains today as secure as ever—indeed, more secure, in light of the Borde-Guth-Vilenkin theorem and that prediction’s corroboration by the repeated and often imaginative attempts to falsify it. The person who believes that the universe began to exist remains solidly and comfortably within mainstream science.

Although an accepted theory of the creation of the universe from nothing does not exist, serious speculations have been proposed by four noted cosmologists: Alexander Vilenkin of Tufts University in Massachusetts, Andrei Linde of Stanford University in California, and working collaboratively, Stephen Hawking of Cambridge University in Great Britain and James Hartle of the University of California at Santa Barbara. These proposals use the unpredictability of quantum theory to explain the origin of the universe as the random creation of space and time out of a state of absolute nothingness. The ideas are only approximate, based on our imperfect understanding of the quantum version of general relativity. While one hopes that someday the origin of the universe will be addressed by superstring theory, at present the theory is not understood well enough to make this possible

Did the Universe Have a Beginning?
Scientific discoveries revive the ancient belief in a beginning to the universe. If we could rewind the history of the universe, what would we discover about its origin and development? Did it really have a beginning, or was it always there?

The influential ancient philosopher Aristotle stated, “It is impossible that movement should ever come into being or cease to be, for it must always have existed. Nor can time come into being or cease to be.”

Meanwhile, the biblical book of Genesis famously starts off, “In the beginning God created the heaven and the earth.”

Which is it? Is the universe eternal—has it always been here? Or did it have a start at some point in time—did it have a birthday, so to speak? These are the two schools of thought that have enrolled followers since early times. (Actually, there was also a third school that postulated that the universe existed on the back of a giant sea turtle, but they’re mostly gone now.)

The seesaw of opinion has tipped one way or the other over time. But lately the weight of evidence has all been coming down on the side of the birthday universe.
In the old days when the Christian church dominated Western society, the creation of the universe was taken for granted. But slowly the scientific viewpoint pushed aside creation as well as the Creator. Now many scientists are thinking that the idea of a creation may not have been so far off from the truth as they thought. It’s looking like the universe had a beginning after all.
Remarkably, one of the first scientists to swing the pendulum of opinion back to the birthday-universe position was so entrenched in eternal-universe thinking that at first he refused to believe his own conclusions.

A GREAT BRAIN'S BIGGEST BLUNDER

When Albert Einstein developed his revolutionary theory of general relativity in 1916, his mathematical calculations pointed to an extraordinary conclusion—the universe was expanding. And since if you rewind the tape on any expansion, you get back to a point where it started, that meant the universe must have had a beginning too.1
Einstein, however, was like most scientists of his day in that he believed in an eternal universe. Unwilling to accept a beginning to the universe, Einstein fudged the numbers in order to nullify the conclusion that the universe was expanding.
University of California astrophysicist George Smoot explains that Einstein’s main problem with an expanding universe was its implication of a beginning. A beginning pointed to a beginner beyond scientific investigation.2 However, once experimental data proved that the universe really was expanding, Einstein admitted his error, calling it “the biggest blunder of my life.”3
There’s a point worth considering here: if it could happen to Einstein, it could happen to anyone. Rarely is anyone completely objective when it comes to the issue of a Creator. While it is true that religious belief and philosophy became an obstacle for scientific inquiry in the days of Galileo, trends have changed. In the modern era it has at times been a prejudice against the possibility of a cosmic designer that has kept many scientists from honest and open inquiry.
Thankfully, the truth generally comes out in the end and scientists begin to see the light. For Einstein and others, it was something called red shift that started the parade of evidence for a universe with a beginning.

RED SHIFING THE BIG BANG THEORY INTO HIGH GEAR

In the late 1920s, the American astronomer Edwin Hubble noticed something unusual as he gazed into the heavens. It wasn’t a new planet or little green men waving at him from Mars; it was something both more tedious and at the same time more thrilling.
Hubble had been spending countless nights at the Mount Wilson Observatory, studying the stars and galaxies and especially the spectrum of color in the light they sent our way. He discovered that the light from most other galaxies was shifted to the red end of the spectrum, which indicated they were moving away from us.

Furthermore, the farther a galaxy was away from us, the more red shifted its light was and, thus, the faster it was moving away from us. The only explanation for all of this was that space itself was expanding, causing all galaxies to move away from each other. In an expanding universe, from any point in space (including our own), it would appear that most stars and galaxies were racing away. And the farther away they were, the faster they would be racing.
There it was in the red shift: proof that Einstein had been right in the first place (before he fudged his formula) and that the universe really was expanding. Proof, in other words, that the universe was not eternal but had a beginning.4
And yet not everyone accepted the proof at first, including a scientist named Sir Fred Hoyle (former Plumian professor of astronomy at Cambridge University and founder of the Institute of Astronomy at Cambridge). Ironically, it was Hoyle who originally described the event as a “big bang,” meaning to mock the idea. The name stuck. (According to physics professor Brian Greene, the term “big bang” is actually misleading since there was nothing to explode and no space in which an explosion could take place.)5 But unlike Hoyle, many other scientists began coming over to the side of the newly named theory.
The world’s leading astrophysicist, Stephen Hawking, who has held the esteemed position of Lucasian Professor of Mathematics at Cambridge, calls Hubble’s discovery of an expanding universe “one of the great intellectual revolutions of the twentieth century.”6 The discovery that the universe had a beginning has led to a new science called cosmology, which attempts to understand what happened at the origin of the universe, how it works, and what will happen in its future.
The new science led cosmologists to take another look at a seemingly mundane insight from the 19th century, the second law of thermodynamics.

A SECOND LAW OF FIRST IMPORTANCE

In addition to Hubble’s discovery, the second law of thermodynamics also predicts a beginning to the universe. You say you don’t know the second law of thermodynamics? Think again.
Let’s say you come into a room containing me and a bunch of your other pals, and you find a steaming cup of Starbucks coffee on the table. Being the thoughtful individual that you are, you ask, “Does this belong to anyone?”
To which I reply, “It’s been there for the last month.”
Well, you’d know immediately I was wrong or lying (probably lying). Why? Because the coffee wouldn’t still be hot if it had been there for a month; it would be room temperature.
That’s the second law of thermodynamics in action. This law states that everything continually moves from a state of order to disorder and that heat and energy dissipate over time. This is a law that has been verified by proof after scientific proof and has never been shown to be wrong.
Now let’s apply this law to the universe, just as cosmologists have. If the universe were eternal, it would have gone cold and lifeless long ago. The stars would have burned out. Planets would have broken up into clouds of dust. And even the black holes would have ceased vacuuming the universe of unsightly stars and planets.
When you see flaming suns and scorching meteors, in other words, you’re looking at a steaming cup of coffee that over infinite time would have long since gone room temperature. Since the universe is still full of pockets of heat and energy, it cannot be eternal. Who would have thought heat would be such a helpful clue? And that is just the half of it.

THE SIGNIFICANCE OF TV INTERFERENCE

There is still another way that the measurement of heat help to prove that the universe is expanding. In the spring of 1964, two researchers at Bell Labs observed a persistent hiss while testing their microwave radiation detector. Regardless of which direction they pointed the antenna, the static was the same. (This is the same static as TV interference. The same static that was supposed to be gone when I paid $150 to have my satellite dish installed.) Those men, Arno Penzias and Robert Wilson, had discovered what scientists say is the echo from the birth of the universe.7

But how could scientists know for sure that the hiss they were hearing was actually an echo from the beginning of the universe? Mathematicians calculated that heat generated at the moment the universe began would have been enormous beyond comprehension. This heat would have gradually dissipated over the life of the cosmos, leaving only a tiny residual of about 3 degrees Kelvin (-270 degrees C).

Additionally, in order for galaxies to have formed by the explosion needed to have slight variations in the form of waves or ripples.

According to George Smoot, these ripples would result in very slight fluctuations in the predicted temperature and would reveal an identifiable pattern.8 Thus, if the temperatures matched up, the birth of the universe would be scientifically verified. Merely discovering the temperature to be 3 degrees Kelvin would not prove that the universe actually had a beginning, the fluctuations also needed to match.9


But how could we verify fluctuations so subtle?

THE GREATEST DISCOVERY OF ALL TIME?

In 1992, a team of astrophysicists led by Smoot launched the COBE satellite in order to verify the temperatures in space. The satellite would be able to take precise measurements and determine whether fluctuations in temperature existed.
The results stunned the scientific world. Not only was the three-degree temperature confirmed, but more importantly, the profiles of the fluctuations were discovered to be a match with what had been expected.10 Hawking called the discovery “the scientific discovery of the century, if not all time.” Smoot himself excitedly stated to newspaper reporters, “What we have found is evidence for the birth of the universe.”11 He also said, “If you’re religious, it’s like looking at God.”12
Astounded by the news, Ted Koppel began his ABC Nightline television program with an astronomer quoting the first two verses of the Bible. The other special guest, a physicist, immediately added his quote of the third Bible verse: “In the beginning God created the heavens and the earth. … And God said, ‘Let there be light,’ and there was light” (Genesis 1:1, 3).13
Evidence like that provided by the COBE satellite raises some intriguing questions, to say the least.

THE QUESTIONS THAT FOLLOW THE EVIDENCE

Einstein’s theorems based on his theory of relativity predict that the universe could not have begun without an outside force or Beginner.14 Since Einstein’s theory of relativity ranks as the most exhaustively tested and best proven principle in physics, his conclusion is deemed correct.15
Tests from an array of radio telescopes at the South Pole have confirmed the big bang to a still higher degree of accuracy than ever before.16 Background radiation measurements exceed 99.9% of what had been predicted.17 There are now more than 30 independent confirmations that the universe had a one-time origin.18
New telescopes such as the infrared Spitzer Space Telescope, launched in 2003, have opened up even bigger windows to our universe. They have prompted astronomer Giovanni Fazio, from the Harvard-Smithsonian Center for Astrophysics, to remark, “We are now able for the first time to lift the cosmic veil that has blocked our view.”19
As a result of the accumulating evidence, the scientific community has long since begun asking questions about origins, such as the following:
• What was there before the big bang?
• Why did the big bang result in a universe enabling life to exist?
• How could everything originate from nothing?
Smoot ponders what was there before the beginning: “Go back further still, beyond the moment of creation—what then? What was there before the big bang? What was there before time began?”20 The same astrophysicist notes that “until the late 1910’s … those who didn’t take Genesis literally had no reason to believe there had been a beginning.”21 The Genesis account of creation and the big bang theory both speak of everything coming from nothing. Suddenly the Bible and science agree (a discovery somewhat embarrassing to materialists). Smoot admits, “There is no doubt that a parallel exists between the big bang as an event and the Christian notion of creation from nothing.”22
The evidence had begun to add up, and some scientists weren’t liking the sum.

TRYING TO AVOID THE BAD DREAM

A beginning to the universe was like a bad dream come true for materialists who wanted to believe everything had always existed. It brought scientists face to face with the loical conclusions that primary cause must exist. That argument is a simple logical syllogism:
1. Everything that has a beginning had a cause.
2. The universe had a beginning.
3. Therefore, the universe had a cause.
But admitting a cause leads to the next logical question: who or what is the cause?
Think about it for a minute. Since time, space, matter, and motion are all a part of the created universe, then before the beginning it was timeless, spaceless, and motionless.
What can happen spontaneously from this state of affairs? There’s nothing moving, there’s nothing colliding, there’s … well, nothing. Not even the potential for anything to happen.
The fact everything came from nothing has forced scientists to acknowledge that something outside of space and time, something very powerful and with apparent volition, must have acted to bring about the beginning. That is, there must have been an intelligent Designer of the universe. Some might go ahead and use the name God for this Creator.
Well, in certain academic circles, this line of reasoning simply won’t do. Thus it is that many materialists have looked for a way to prove that the universe didn’t have a beginning. Smoot remarks, “Cosmologists have long struggled to avoid this bad dream by seeking explanations of the universe that avoid the necessity of a beginning.”23
Sir Fred Hoyle (he who mockingly coined the term “big bang”) was one scientist who strongly opposed the concept of a beginning for the universe. In 1948 Hermann Bondi and Thomas Gold joined Hoyle in postulating that matter was in a continual state of creation. They called their idea the steady state theory, which was an attempt to show that the universe is eternal after all, even though the evidence had long been trending against such a view. However, the COBE discovery of background radiation was the fatal blow to the steady state theory. 24
Next came the oscillating-universe theory. According to this concept, the universe explodes, contracts, and explodes again, eternally yo-yoing. This would be another way to permit a belief in the eternal existence of the universe. But the physics for this theory didn’t work.
More recently, some scientists, including Hawking, have begun considering the so-called multiverse theory. This theory accepts that our universe is finite, but it suggests that ours is just one of many universes. The whole multi-universe may be eternal, according to this theory, even though our particular universe is not. This theory is covered in more depth in another article in this magazine, but the key point to understand about it right now is that it has no evidence whatsoever to support it.
These theories fit neatly with the philosophy of materialism, whereas a beginning of the universe would raise the obvious question, who was there to start it? Professor Dennis Sciama, Hawking’s supervisor while he was at Cambridge, admits his reasons for supporting the steady state theory: “I was a supporter of the steady state theory, not in the sense that I believed that it had to be true, but in that I found it so attractive I wanted it to be true.”25
An origin of the universe meant materialists were suddenly faced with the questions that threatened their worldview.

A ONE TIME BEGINNING

Hoyle and other scientists fervently pursued alternative explanations to a one-time origin of the universe. Eventually, however, the evidence showed clearly that the universe had a beginning, and the big bang theory was proclaimed victorious. Ironically, it was evidence from Hoyle’s own research that helped confirm that the universe had a one-time beginning.
Today most cosmologists and physicists accept the big bang theory as the scientific explanation of how our universe began. In fact, scientists believe they can trace the history of the universe all the way back to 10-43 of a second. Prior to that point in the history of our universe, all of our current theories break down and science can see no further back. The very beginning of the universe remains a mystery.
Imagine rewinding the universe back to its beginning, a time when there were no stars. No light, matter, or energy. Not even space or time. Suddenly an enormous explosion erupted from this nothingness at a temperature exceeding a million trillion trillion degrees.26 Time begins along with matter, energy, and space.
When a bomb ejects shrapnel into the air, both the bomb material and the space it blows into have already been there. However, in the beginning of the universe, neither space nor matter existed until the explosion. The space surface of the universe and the newly created matter came into existence.
According to the big bang theory, this explosion launched the entire universe, from the most distant galaxy, to the most colorful nebula, to quasars flashing like beacons, to our own comforting sun and nearby planets, to you and me with our questions about where we came from and what it all means. Since man alone thinks about the meaning and purpose of life, the beginning—and the cause of that beginning—must be fascinating to each one of us.
The verdict is in on the question of whether the universe is eternal or had a beginning. The idea that everything in the cosmos originated out of nothing seems mythical, yet it is now mainstream science.

In order to appreciate this discovery, we must first try to forget the Bible. It’s not easy for us Westerners to empty our heads of the idea that in the beginning, God created the heavens and the earth. But human tradition has always assumed that the universe had no particular beginning (the sole exception being the Bible and those religions influenced by it). The ancients didn’t believe that the gods created the universe out of nothing, but that the gods formed it out of an eternal, watery mush that existed before them. And from Aristotle to Einstein, the scientific view was that the universe has simply always been here, thus relieving scientists of the burden of having to deal with the question of ultimate origins.

Scientists today can no longer be so complacent. In his foreword to my book, Show Me God, George Smoot (head of the NASA COBE satellite team that discovered cosmic "seeds") says: "Until the late 1910s, humans were as ignorant of cosmic origins as they had ever been. Those who didn’t take Genesis literally had no reason to believe there had been a beginning."

Evidences for a beginning

Relativity. Strong evidence for a creation event in this century began with Einstein’s general theory of relativity, which predicted the universe’s expansion. Einstein himself refused to believe it for years. Expansion implied a beginning and a beginning implied a Beginner.

Hubble Expansion. The evidence became undeniable, however, when Edwin Hubble used the largest telescope of his time to discover that all the galaxies are rushing away from us, and that there was a precise, linear relationship between the galaxies’ distance and their velocity, as Einstein’s equations had predicted.

Abundance of Helium. Later discoveries continued to confirm the "big bang," as Fred Hoyle jokingly first called it. While Hoyle was trying to prove his steady state theory of an eternal universe, he instead proved that only an incredibly hot, condensed beginning for the universe could explain the abundance of helium in the universe.

Remnant Radiation. Early big bang theorists predicted that we should be able to detect left-over radiation from the heat of this early dense state, since there is nowhere "outside" the universe for it to escape. Bell Lab’s Arno Penzias and Robert Wilson won the Nobel prize for their accidental discovery of this radiation with the world’s most sensitive low-temperature radio telescope.

"What we found," Penzias told me, "was radiation for which there is no known source in the universe." And this pointed the two discoverers away from their previously held belief that the universe was eternal to belief in what Penzias calls "a creation out of nothing."

Since then, NASA’s COBE satellite measured the precise signature of what’s known as the ‘blackbody’ radiation formed by this microwave background, the spectrum of an event too powerful to be explained by anything in this universe, but expected to characterize the entire universe at its creation. Recognizing this precise curve on his monitor during the first COBE measurement, Richard Isaacman said, "I felt like I was looking God in the face."

"Fingerprints from the Maker." George Smoot’s discovery of the predicted ripples in this microwave background yielded still more evidence for the modern theory of a creation event. "It’s really like looking back at creation," says Smoot, "and seeing the creation of space and time and the universe and everything in it, but also the fingerprints from the Maker, and those very neatly turn out to be the things that caused the universe to be very interesting to us: namely, creating galaxies and stars." Slightly larger or smaller ripples, he points out, would result in a universe filled with black holes or thin soup, rather than stars and planets.

Baby Galaxies. The latest discovery is something astronomers have long sought as their "holy grail": primeval galaxies. Finding them would be the most direct evidence possible to show that our universe has truly changed with time. If the Hubble expansion truly implies a creation event, then looking back in time far enough should show us an epoch when all the galaxies were forming, and before that, an epoch when the galaxies had not yet begun to light up at all. But until very recently, astronomers saw fairly normal looking galaxies as far back in time (and distance) as they observed.

All this has changed in 1996, when a team led by Caltech astronomer Chuck Steidel used his ultraviolet dropout technique to find many galaxies beyond a redshift of 2. "We’re seeing the central bulge regions of galaxies forming," he told me, "where you expect all of the star formation to be happening in a relatively small region." Moreover, beyond a redshift of 4, he finds he has suddenly entered an era where galaxies have not yet formed at all.

An outside job

The great quest of science is to find the cause for every effect. But as we trace the cause-effect chain back through time, we come to a scientifically embarrassing moment at the beginning where cause-effect relationships simply stop.

Arno Penzias told me: "So what we find – the simplest theory – the one that the astronomers normally espouse, is a creation out of nothing, the appearance out of nothing of a universe." And in my most recent interview with Robert Jastrow, he said, "It's a curiously theological result to come out of science."

It’s "theological" because the Bible also teaches creation out of nothing (creation ex nihilo, Hebrews 11:3). I can’t stress enough, however, that it’s not the theology of any of the other world’s religions coming to us from ancient times. No other culture – Egyptian, Babylonian, Sumerian, etc., can be said to have influenced the Hebrews in this regard. Many modern scientists have come to recognize that, in George Smoot’s words, "there is no doubt that a parallel exists between the big bang as an event and the Christian notion of creation from nothing."

Einstein first taught us that space, time, and matter are inextricably linked. The expansion of the universe is not a matter of galaxies being flung out into a larger void, but of space itself stretching and taking galaxies along for the ride. This means that if our backward journey through time ends with the disappearance of matter, then time and space must disappear too.

Logic tells us that causes must precede their effects. So what should we think about the cause for this universe when there is no time before the beginning? A cause must be separate from its effect, meaning that the cause of our universe must be placed squarely outside of it. And this is the first thing these discoveries in cosmology suggest about the universe’s greatest mystery, the greatest whodunit of all time: it was an outside job.

A Creator outside of space

Once again, only the ancient Hebrews got their cosmology right. British astrophysicist Fred Hoyle recognized this when he wrote: "The general concept of gods located fairly and squarely within the Universe was common in ancient times throughout the Near East. The Hebrew departure from this position was evidently very great."

The Bible proclaims a God who is non-physical. Unlike every other ancient deity, the God of the Hebrews didn’t permit images to be made of Himself, as if He were merely a physical God. Moses reminded the people that, even in their closest contact with God, "you saw no form of any kind the day the LORD spoke to you.... Therefore watch yourselves very carefully, so that you do not become corrupt and make for yourselves an idol, an image of any shape" (Deut. 4:15-16).

This God could not be contained by the universe. King Solomon prayed: "The heavens, even the highest heaven, cannot contain you. How much less this temple I have built!" (1 Kings 8:27). Obviously, the concept was very different from the picture of physical gods held by others in the ancient world: sun gods, moon gods, star gods, river gods, animal-headed gods and goddesses, etc.

And today, if science points to a Creator who must be separate from the physical universe, then pantheistic ideas of God appear to be as misconstrued as polytheistic ones. The Eastern notion of a "Star Wars" God, a God who is a mere "Force" that is one with or part of the universe, is seriously challenged by modern cosmology.

There are some disquieting issues with this theory, at least to the non-Physicists. First, the singularity did not appear in space. Space did not exist before the big Bang and in fact, had to begin inside the singularity. Prior to the singularity, nothing existed. So, where did it come from and why? We don’t know. All we do know is that we exist within space and at one time it did not exist and neither did we.

The Universe is Not Eternal, But Had A Beginning

I recently received an e-mail claiming that most scientists do not believe that the Big Bang represents the beginning of the universe. Other visitors to the site have made similar claims in the past, so I thought it would be a good idea to set the record straight about the origin of the universe. Although there are atheistic scientists who believe that the universe existed before the Big Bang, I must make it clear that they present no evidence for this belief, since none exists! This kind of belief is metaphysical in nature as indicated in an article from the The Origin-of-Life Foundation, Inc.®:

"Appeals to multiple or 'parallel' cosmoses or to an infinite number of cosmic 'Big Bang/Crunch' oscillations as essential elements of proposed mechanisms are not acceptable in submissions due to a lack of empirical correlation and testability. Such beliefs are without hard physical evidence and must therefore be considered unfalsifiable, currently outside the methodology of scientific investigation to confirm or disprove, and therefore more mathematically theoretical and metaphysical than scientific in nature. Recent cosmological evidence also suggests insufficient mass for gravity to reverse continuing cosmic expansion. The best cosmological evidence thus far suggests the cosmos is finite rather than infinite in age."1

Such metaphysical beliefs are often incorporated in popular books about cosmology, although it is seldom stated that those beliefs are without any evidence. Here are some quotes from university websites by scientists who know that the universe had a beginning:

"The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago." Stephen Hawking The Beginning of Time
"Scientists generally agree that "the Big Bang" birthed the universe about 15 billion years ago." Tom Parisi, Northern Illinois University
"As a result of the Big Bang (the tremendous explosion which marked the beginning of our Universe), the universe is expanding and most of the galaxies within it are moving away from each other." CalTech
"The Big Bang model of the universe's birth is the most widely accepted model that has ever been conceived for the scientific origin of everything." Stuart Robbins, Case Western Reserve University
"Many once believed that the universe had no beginning or end and was truly infinite. Through the inception of the Big Bang theory, however, no longer could the universe be considered infinite. The universe was forced to take on the properties of a finite phenomenon, possessing a history and a beginning." Chris LaRocco and Blair Rothstein, University of Michigan
"The scientific evidence is now overwhelming that the Universe began with a "Big Bang" ~15 billion (15,000,000,000 or 15E9) years ago." "The Big Bang theory is the most widely accepted theory of the creation of the Universe." Dr. van der Pluijm, University of Michigan
"The present location and velocities of galaxies are a result of a primordial blast known as the BIG BANG. It marked: THE BEGINNING OF THE UNIVERSE! THE BEGINNING OF TIME!" Terry Herter, Cornell University
"That radiation is residual heat from the Big Bang, the event that sparked the beginning of the universe some 13 billion years ago." Craig Hogan, University of Washington
"Most scientists agree that the universe began some 12 to 20 billion years ago in what has come to be known as the Big Bang (a term coined by the English astrophysicist Fred Hoyle in 1950." University of Illinois
"The universe cannot be infinitely large or infinitely old (it evolves in time)." Nilakshi Veerabathina, Georgia State University ()
"The universe had a beginning. There was once nothing and now there is something." Janna Levin, Department of Applied Mathematics and Theoretical Physics at Cambridge University
"Today scientists generally believe the universe was created in a violent explosion called the Big Bang." Susan Terebey, Department of Physics and Astronomy, California State University Los Angeles
"Evidence suggests that our universe began as an incredibly hot and dense region referred to as a singularity." Stephen T. Abedon, Ohio State University
"A large body of astrophysical observations now clearly points to a beginning for our universe about 15 billion years ago in a cataclysmic outpouring of elementary particles. There is, in fact, no evidence that any of the particles of matter with which we are now familiar existed before this great event." Louis J. Clavelli, Ph.D., Professor of Physics, University of Alabama
"Now, after decades of observing and thinking, we have come to answer confidently the question of the origin of our universe... with what is known as the "big bang"." Yuki D. Takahashi, Caltech
"The theory is the conceptual and the calculational tool used by particle physicists to describe the structure of the hadrons and the beginning of the universe." Keh-Fei Liu, University of Kentucky.
"The three-part lecture series includes: "How the Universe Began," "The Dark Side of the Universe: Dark Matter and Dark Energy" and "Cosmic Inflation: The Dynamite Behind the Big Bang?" (Lectures by Michael S. Turner, Bruce V. and Diana M. Rauner at Penn State University)
"Travel back in time to the beginning of the Universe: The Big Bang" Douglas Miller, University of Arizona
"Beginning of the Universe 20.0 billion yr ago" Charly Mallery, University of Miami
"At the beginning the universe was extremely hot and dense (more about this later) and as it expanded it cooled." Syracuse University
"THE UNIVERSE AND ALL OF SPACE ARE EXPANDING FROM A BIG BANG BEGINNING" Center for Cosmological Physics, University of Chicago
"Gamow realized that at a point a few minutes after its beginning, the universe would behave as a giant nuclear reactor." Valparaiso University, Department of Physics and Astronomy
"I'll also include what the time is since the creation of the Universe, and an estimate of the temperature of the Universe at each point." Siobahn M. Morgan, University of Northern Iowa.
"The Universe is thought to have formed between 6-20 billion years ago (Ga) as a result of the "Big Bang" Kevin P. Hefferan, University of Wisconsin-Stevens Point
"The dominant idea of Cosmology is that the Universe had a beginning." Adam Frank, University of Rochester Department of Physics & Astronomy
"The hot dense phase is generally regarded as the beginning of the universe, and the time since the beginning is, by definition, the age of the universe." Harrison B. Prosper, Florida State University
"One of the major hypotheses on which modern cosmology is based is that the Universe originated in an explosion called the Big Bang, in which all energy (and matter) that exists today was created." Eric S. Rowland, UC Santa Cruz
"Together with Roger Penrose, I developed a new set of mathematical techniques, for dealing with this and similar problems. We showed that if General Relativity was correct, any reasonable model of the universe must start with a singularity. This would mean that science could predict that the universe must have had a beginning, but that it could not predict how the universe should begin: for that one would have to appeal to God." Stephen W. Hawking "Origin of the Universe" lecture

Scientific Evidence for a Beginning
The universe is not eternal
Discovery of the 1920's

Before the 1920s, most people believed that the universe did not have a beginning. People thought the universe was eternal. And few people ever thought that the sun would run out of fuel.

But in the 1920s, new facts from science made people question the standard view of the universe. At that time, a man named Edwin Hubble used the most distant viewing telescope in the world. He aimed at star systems with millions or billions of stars called galaxies. Almost all stars are part of a galaxy. We live in the Milky Way galaxy, which may have up to 100 billion stars. Hubble was the first man to know there were other galaxies beyond the Milky Way. He also grouped them together based on their shapes. And Edwin Hubble is given honor as the person who found out that galaxies exist.

The result of Hubble finding galaxies changed the way we view the universe based on how galaxies move. Hubble found out that most galaxies are moving away from each other at very high speeds. The further away a galaxy is from earth, the faster it is moving. Other scientists looked at the stars, reviewed the data, and agreed with Hubble. These findings led Hubble to think that the universe is expanding. It soon became a fact that distant galaxies move away from one another at very high speeds. This has been found true except for galaxies that are close together. When galaxies are close to one another, gravity pulls them together. Given enough time, these galaxies move toward each other at higher and higher speeds until they crash into each other. Have you ever witnessed two cars having a wreck? Imagine a huge star on the loose crashing into the sun. That would be the end of life on earth. Don't worry about that because it will never happen in our lifetime. In a few pages forward, you can look at some photos of galaxies crashing into each other.

Based on how distant galaxies move away from each other, new ideas about the universe came about. These ideas have been widely accepted by almost all scientists. The first new idea is that the universe is getting bigger as time passes. And the second idea relates to how far apart the galaxies are from one another. The most distant galaxies are moving away at faster rates than those not as far away. Or we could say the more distant galaxies are moving away at ever-greater speeds. This is called the Hubble constant.

So how did people accept these new ideas? New facts can cause a lot of change. And this turned out to be a big one.

Now dream with me. Imagine if you were to make a motion picture of all the galaxies moving apart from one another. As time passed by, the galaxies move further and further apart. After we have made the movie, we decide to rewind it and watch the galaxies as they move back in time to their dawning. We would see the galaxies moving closer and closer together as the movie approaches its beginning. Each large spiral looking galaxy would seem to split up into several smaller round baby galaxies. Then these small baby-looking galaxies would appear to dissolve into an extremely bright and extremely hot broiling soup. Our mouths would drop in awe as we watched the entire universe shrink into a small volume and disappear at the speed of light. We may even think that the whole universe came from nothing. Perhaps the easiest way of saying this is that the universe appears to have come from some type of gigantic energy release. This is where the idea of the so-called "BIG BANG" theory comes from. The fact that galaxies are moving away from one another supports the Big Bang idea.

What is so important about the Big Bang theory? By far, the most important idea is that it tells us the universe had a beginning. The universe began. And the universe will end.

However, at the very start of the Big Bang Theory, many intelligent people did not like the idea that the universe had a beginning. To question the Big Bang theory, some scientists came up with new ideas. These scientists "held onto the view" the universe did not have a beginning. This was called the "steady-state" universe. To make the "steady-state" universe look good; their idea had to account for the new proven facts such as the universe is getting bigger as time passes. To take this idea in account, these scientists thought that new matter appears as time passes. If this were so, the universe would look the same forever. As the galaxies moved apart, new matter would appear and create new stars and new galaxies. The new matter idea would make the universe appear to be unchanging as time passed. The universe would be eternal if this were true.

The "Big Bang" theory was thought to be false by people who accepted the "steady state" theory of the universe. To maintain the idea that the universe had a beginning, more facts were needed. A new finding in 1965 gave the Big Bang theory a new boost. This new finding and many others have made the Big Bang theory appear to be true. At the very least, the Big Bang theory may explain how and when the universe began. Let's review the other facts that support the Big Bang theory. I will give a title to the next five ideas that support the Big Bang Theory as noted below. To ensure you understand that science supports the universe had a beginning, it is suggested that read these in sequence.

In this lecture, I would like to discuss whether time itself has a beginning, and whether it will have an end. All the evidence seems to indicate, that the universe has not existed forever, but that it had a beginning, about 15 billion years ago. This is probably the most remarkable discovery of modern cosmology. Yet it is now taken for granted. We are not yet certain whether the universe will have an end. When I gave a lecture in Japan, I was asked not to mention the possible re-collapse of the universe, because it might affect the stock market. However, I can re-assure anyone who is nervous about their investments that it is a bit early to sell: even if the universe does come to an end, it won't be for at least twenty billion years. By that time, maybe the GATT trade agreement will have come into effect.

The time scale of the universe is very long compared to that for human life. It was therefore not surprising that until recently, the universe was thought to be essentially static, and unchanging in time. On the other hand, it must have been obvious, that society is evolving in culture and technology. This indicates that the present phase of human history can not have been going for more than a few thousand years. Otherwise, we would be more advanced than we are. It was therefore natural to believe that the human race, and maybe the whole universe, had a beginning in the fairly recent past. However, many people were unhappy with the idea that the universe had a beginning, because it seemed to imply the existence of a supernatural being who created the universe. They preferred to believe that the universe, and the human race, had existed forever. Their explanation for human progress was that there had been periodic floods, or other natural disasters, which repeatedly set back the human race to a primitive state.

This argument about whether or not the universe had a beginning, persisted into the 19th and 20th centuries. It was conducted mainly on the basis of theology and philosophy, with little consideration of observational evidence. This may have been reasonable, given the notoriously unreliable character of cosmological observations, until fairly recently. The cosmologist, Sir Arthur Eddington, once said, 'Don't worry if your theory doesn't agree with the observations, because they are probably wrong.' But if your theory disagrees with the Second Law of Thermodynamics, it is in bad trouble. In fact, the theory that the universe has existed forever is in serious difficulty with the Second Law of Thermodynamics. The Second Law, states that disorder always increases with time. Like the argument about human progress, it indicates that there must have been a beginning. Otherwise, the universe would be in a state of complete disorder by now, and everything would be at the same temperature. In an infinite and everlasting universe, every line of sight would end on the surface of a star. This would mean that the night sky would have been as bright as the surface of the Sun. The only way of avoiding this problem would be if, for some reason, the stars did not shine before a certain time.

In a universe that was essentially static, there would not have been any dynamical reason, why the stars should have suddenly turned on, at some time. Any such "lighting up time" would have to be imposed by an intervention from outside the universe. The situation was different, however, when it was realised that the universe is not static, but expanding. Galaxies are moving steadily apart from each other. This means that they were closer together in the past. One can plot the separation of two galaxies, as a function of time. If there were no acceleration due to gravity, the graph would be a straight line. It would go down to zero separation, about twenty billion years ago. One would expect gravity, to cause the galaxies to accelerate towards each other. This will mean that the graph of the separation of two galaxies will bend downwards, below the straight line. So the time of zero separation, would have been less than twenty billion years ago.

At this time, the Big Bang, all the matter in the universe, would have been on top of itself. The density would have been infinite. It would have been what is called, a singularity. At a singularity, all the laws of physics would have broken down. This means that the state of the universe, after the Big Bang, will not depend on anything that may have happened before, because the deterministic laws that govern the universe will break down in the Big Bang. The universe will evolve from the Big Bang, completely independently of what it was like before. Even the amount of matter in the universe, can be different to what it was before the Big Bang, as the Law of Conservation of Matter, will break down at the Big Bang.

Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there's no way one could measure what happened at them. This kind of beginning to the universe, and of time itself, is very different to the beginnings that had been considered earlier. These had to be imposed on the universe by some external agency. There is no dynamical reason why the motion of bodies in the solar system can not be extrapolated back in time, far beyond four thousand and four BC, the date for the creation of the universe, according to the book of Genesis. Thus it would require the direct intervention of God, if the universe began at that date. By contrast, the Big Bang is a beginning that is required by the dynamical laws that govern the universe. It is therefore intrinsic to the universe, and is not imposed on it from outside.

Although the laws of science seemed to predict the universe had a beginning, they also seemed to predict that they could not determine how the universe would have begun. This was obviously very unsatisfactory. So there were a number of attempts to get round the conclusion, that there was a singularity of infinite density in the past. One suggestion was to modify the law of gravity, so that it became repulsive. This could lead to the graph of the separation between two galaxies, being a curve that approached zero, but didn't actually pass through it, at any finite time in the past. Instead, the idea was that, as the galaxies moved apart, new galaxies were formed in between, from matter that was supposed to be continually created. This was the Steady State theory, proposed by Bondi, Gold, and Hoyle.

The Steady State theory, was what Karl Popper would call, a good scientific theory: it made definite predictions, which could be tested by observation, and possibly falsified. Unfortunately for the theory, they were falsified. The first trouble came with the Cambridge observations, of the number of radio sources of different strengths. On average, one would expect that the fainter sources would also be the more distant. One would therefore expect them to be more numerous than bright sources, which would tend to be near to us. However, the graph of the number of radio sources, against there strength, went up much more sharply at low source strengths, than the Steady State theory predicted.

There were attempts to explain away this number count graph, by claiming that some of the faint radio sources, were within our own galaxy, and so did not tell us anything about cosmology. This argument didn't really stand up to further observations. But the final nail in the coffin of the Steady State theory came with the discovery of the microwave background radiation, in 1965. This radiation is the same in all directions. It has the spectrum of radiation in thermal equilibrium at a temperature of 2 point 7 degrees above the Absolute Zero of temperature. There doesn't seem any way to explain this radiation in the Steady State theory.

Another attempt to avoid a beginning to time, was the suggestion, that maybe all the galaxies didn't meet up at a single point in the past. Although on average, the galaxies are moving apart from each other at a steady rate, they also have small additional velocities, relative to the uniform expansion. These so-called "peculiar velocities" of the galaxies, may be directed sideways to the main expansion. It was argued, that as you plotted the position of the galaxies back in time, the sideways peculiar velocities, would have meant that the galaxies wouldn't have all met up. Instead, there could have been a previous contracting phase of the universe, in which galaxies were moving towards each other. The sideways velocities could have meant that the galaxies didn't collide, but rushed past each other, and then started to move apart. There wouldn't have been any singularity of infinite density, or any breakdown of the laws of physics. Thus there would be no necessity for the universe, and time itself, to have a beginning. Indeed, one might suppose that the universe had oscillated, though that still wouldn't solve the problem with the Second Law of Thermodynamics: one would expect that the universe would become more disordered each oscillation. It is therefore difficult to see how the universe could have been oscillating for an infinite time.

This possibility, that the galaxies would have missed each other, was supported by a paper by two Russians. They claimed that there would be no singularities in a solution of the field equations of general relativity, which was fully general, in the sense that it didn't have any exact symmetry. However, their claim was proved wrong, by a number of theorems by Roger Penrose and myself. These showed that general relativity predicted singularities, whenever more than a certain amount of mass was present in a region. The first theorems were designed to show that time came to an end, inside a black hole, formed by the collapse of a star. However, the expansion of the universe, is like the time reverse of the collapse of a star. I therefore want to show you, that observational evidence indicates the universe contains sufficient matter, that it is like the time reverse of a black hole, and so contains a singularity.

In order to discuss observations in cosmology, it is helpful to draw a diagram of events in space and time, with time going upward, and the space directions horizontal. To show this diagram properly, I would really need a four dimensional screen. However, because of government cuts, we could manage to provide only a two dimensional screen. I shall therefore be able to show only one of the space directions.

As we look out at the universe, we are looking back in time, because light had to leave distant objects a long time ago, to reach us at the present time. This means that the events we observe lie on what is called our past light cone. The point of the cone is at our position, at the present time. As one goes back in time on the diagram, the light cone spreads out to greater distances, and its area increases. However, if there is sufficient matter on our past light cone, it will bend the rays of light towards each other. This will mean that, as one goes back into the past, the area of our past light cone will reach a maximum, and then start to decrease. It is this focussing of our past light cone, by the gravitational effect of the matter in the universe, that is the signal that the universe is within its horizon, like the time reverse of a black hole. If one can determine that there is enough matter in the universe, to focus our past light cone, one can then apply the singularity theorems, to show that time must have a beginning.

How can we tell from the observations, whether there is enough matter on our past light cone, to focus it? We observe a number of galaxies, but we can not measure directly how much matter they contain. Nor can we be sure that every line of sight from us will pass through a galaxy. So I will give a different argument, to show that the universe contains enough matter, to focus our past light cone. The argument is based on the spectrum of the microwave background radiation. This is characteristic of radiation that has been in thermal equilibrium, with matter at the same temperature. To achieve such an equilibrium, it is necessary for the radiation to be scattered by matter, many times. For example, the light that we receive from the Sun has a characteristically thermal spectrum. This is not because the nuclear reactions, which go on in the centre of the Sun, produce radiation with a thermal spectrum. Rather, it is because the radiation has been scattered, by the matter in the Sun, many times on its way from the centre.

In the case of the universe, the fact that the microwave background has such an exactly thermal spectrum indicates that it must have been scattered many times. The universe must therefore contain enough matter, to make it opaque in every direction we look, because the microwave background is the same, in every direction we look. Moreover, this opacity must occur a long way away from us, because we can see galaxies and quasars, at great distances. Thus there must be a lot of matter at a great distance from us. The greatest opacity over a broad wave band, for a given density, comes from ionised hydrogen. It then follows that if there is enough matter to make the universe opaque, there is also enough matter to focus our past light cone. One can then apply the theorem of Penrose and myself, to show that time must have a beginning.

The focussing of our past light cone implied that time must have a beginning, if the General Theory of relativity is correct. But one might raise the question, of whether General Relativity really is correct. It certainly agrees with all the observational tests that have been carried out. However these test General Relativity, only over fairly large distances. We know that General Relativity can not be quite correct on very small distances, because it is a classical theory. This means, it doesn't take into account, the Uncertainty Principle of Quantum Mechanics, which says that an object can not have both a well defined position, and a well defined speed: the more accurately one measures the position, the less accurately one can measure the speed, and vice versa. Therefore, to understand the very high-density stage, when the universe was very small, one needs a quantum theory of gravity, which will combine General Relativity with the Uncertainty Principle.

Many people hoped that quantum effects, would somehow smooth out the singularity of infinite density, and allow the universe to bounce, and continue back to a previous contracting phase. This would be rather like the earlier idea of galaxies missing each other, but the bounce would occur at a much higher density. However, I think that this is not what happens: quantum effects do not remove the singularity, and allow time to be continued back indefinitely. But it seems that quantum effects can remove the most objectionable feature, of singularities in classical General Relativity. This is that the classical theory, does not enable one to calculate what would come out of a singularity, because all the Laws of Physics would break down there. This would mean that science could not predict how the universe would have begun. Instead, one would have to appeal to an agency outside the universe. This may be why many religious leaders, were ready to accept the Big Bang, and the singularity theorems.

It seems that Quantum theory, on the other hand, can predict how the universe will begin. Quantum theory introduces a new idea, that of imaginary time. Imaginary time may sound like science fiction, and it has been brought into Doctor Who. But nevertheless, it is a genuine scientific concept. One can picture it in the following way. One can think of ordinary, real, time as a horizontal line. On the left, one has the past, and on the right, the future. But there's another kind of time in the vertical direction. This is called imaginary time, because it is not the kind of time we normally experience. But in a sense, it is just as real, as what we call real time.

The three directions in space, and the one direction of imaginary time, make up what is called a Euclidean space-time. I don't think anyone can picture a four dimensional curve space. But it is not too difficult to visualise a two dimensional surface, like a saddle, or the surface of a football.

In fact, James Hartle of the University of California Santa Barbara, and I have proposed that space and imaginary time together, are indeed finite in extent, but without boundary. They would be like the surface of the Earth, but with two more dimensions. The surface of the Earth is finite in extent, but it doesn't have any boundaries or edges. I have been round the world, and I didn't fall off.

If space and imaginary time are indeed like the surface of the Earth, there wouldn't be any singularities in the imaginary time direction, at which the laws of physics would break down. And there wouldn't be any boundaries, to the imaginary time space-time, just as there aren't any boundaries to the surface of the Earth. This absence of boundaries means that the laws of physics would determine the state of the universe uniquely, in imaginary time. But if one knows the state of the universe in imaginary time, one can calculate the state of the universe in real time. One would still expect some sort of Big Bang singularity in real time. So real time would still have a beginning. But one wouldn't have to appeal to something outside the universe, to determine how the universe began. Instead, the way the universe started out at the Big Bang would be determined by the state of the universe in imaginary time. Thus, the universe would be a completely self-contained system. It would not be determined by anything outside the physical universe, that we observe.

The no boundary condition, is the statement that the laws of physics hold everywhere. Clearly, this is something that one would like to believe, but it is a hypothesis. One has to test it, by comparing the state of the universe that it would predict, with observations of what the universe is actually like. If the observations disagreed with the predictions of the no boundary hypothesis, we would have to conclude the hypothesis was false. There would have to be something outside the universe, to wind up the clockwork, and set the universe going. Of course, even if the observations do agree with the predictions, that does not prove that the no boundary proposal is correct. But one's confidence in it would be increased, particularly because there doesn't seem to be any other natural proposal, for the quantum state of the universe.

The no boundary proposal, predicts that the universe would start at a single point, like the North Pole of the Earth. But this point wouldn't be a singularity, like the Big Bang. Instead, it would be an ordinary point of space and time, like the North Pole is an ordinary point on the Earth, or so I'm told. I have not been there myself.

According to the no boundary proposal, the universe would have expanded in a smooth way from a single point. As it expanded, it would have borrowed energy from the gravitational field, to create matter. As any economist could have predicted, the result of all that borrowing, was inflation. The universe expanded and borrowed at an ever-increasing rate. Fortunately, the debt of gravitational energy will not have to be repaid until the end of the universe.

Eventually, the period of inflation would have ended, and the universe would have settled down to a stage of more moderate growth or expansion. However, inflation would have left its mark on the universe. The universe would have been almost completely smooth, but with very slight irregularities. These irregularities are so little, only one part in a hundred thousand, that for years people looked for them in vain. But in 1992, the Cosmic Background Explorer satellite, COBE, found these irregularities in the microwave background radiation. It was an historic moment. We saw back to the origin of the universe. The form of the fluctuations in the microwave background agree closely with the predictions of the no boundary proposal. These very slight irregularities in the universe would have caused some regions to have expanded less fast than others. Eventually, they would have stopped expanding, and would have collapsed in on themselves, to form stars and galaxies. Thus the no boundary proposal can explain all the rich and varied structure, of the world we live in. What does the no boundary proposal predict for the future of the universe? Because it requires that the universe is finite in space, as well as in imaginary time, it implies that the universe will re-collapse eventually. However, it will not re-collapse for a very long time, much longer than the 15 billion years it has already been expanding. So, you will have time to sell your government bonds, before the end of the universe is nigh. Quite what you invest in then, I don't know.

Originally, I thought that the collapse, would be the time reverse of the expansion. This would have meant that the arrow of time would have pointed the other way in the contracting phase. People would have gotten younger, as the universe got smaller. Eventually, they would have disappeared back into the womb.

However, I now realise I was wrong, as these solutions show. The collapse is not the time reverse of the expansion. The expansion will start with an inflationary phase, but the collapse will not in general end with an anti inflationary phase. Moreover, the small departures from uniform density will continue to grow in the contracting phase. The universe will get more and more lumpy and irregular, as it gets smaller, and disorder will increase. This means that the arrow of time will not reverse. People will continue to get older, even after the universe has begun to contract. So it is no good waiting until the universe re-collapses, to return to your youth. You would be a bit past it, anyway, by then.

The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down. Nevertheless, the way the universe began would have been determined by the laws of physics, if the universe satisfied the no boundary condition. This says that in the imaginary time direction, space-time is finite in extent, but doesn't have any boundary or edge. The predictions of the no boundary proposal seem to agree with observation. The no boundary hypothesis also predicts that the universe will eventually collapse again. However, the contracting phase, will not have the opposite arrow of time, to the expanding phase. So we will keep on getting older, and we won't return to our youth. Because time is not going to go backwards, I think I better stop now.

Back in the late '60s and early '70s, when men first walked upon the moon, "three British astrophysicists, Steven Hawking, George Ellis, and Roger Penrose turned their attention to the Theory of Relativity and its implications regarding our notions of time. In 1968 and 1970, they published papers in which they extended Einstein's Theory of General Relativity to include measurements of time and space.1, 2 According to their calculations, time and space had a finite beginning that corresponded to the origin of matter and energy."3 The singularity didn't appear in space; rather, space began inside of the singularity. Prior to the singularity, nothing existed, not space, time, matter, or energy - nothing. So where and in what did the singularity appear if not in space? We don't know.