Saturday, September 10, 2016

Quantum Fluctuation


Quantum Fluctuation
Multiple Responses:
In quantum physics, a quantum fluctuation (or quantum vacuum fluctuation or vacuum fluctuation) is the temporary change in the amount of energy in a point in space, as explained in Werner Heisenberg's uncertainty principle.

According to one formulation of the principle, energy and time can be related by the relation
\Delta E \Delta t \geq {h \over 4 \pi}

This allows the creation of particle-antiparticle pairs of virtual particles. The effects of these particles are measurable, for example, in the effective charge of the electron, different from its "naked" charge.

In the modern view, energy is always conserved, but the eigenstates of the Hamiltonian (energy observable) are not the same as (i.e., the Hamiltonian does not commute with) the particle number operators.

Quantum fluctuations may have been very important in the origin of the structure of the universe: according to the model of inflation the ones that existed when inflation began were amplified and formed the seed of all current observed structure. Vacuum energy may also be responsible for the current accelerated expansion of the universe (cosmological constant).

Quantum Fluctuation
Quantum fluctuation is the temporary appearance of energetic particles out of nothing, as allowed by the Uncertainty Principle. It is synonymous with vacuum fluctuation.

The Uncertainty Principle states that for a pair of conjugate variables such as position/momentum and energy/time, it is impossible to have a precisely determined value of each member of the pair at the same time. For example, a particle pair can pop out of the vacuum during a very short time interval.

The uncertainty principle is illustrated with a schematic representation on the left. An extension is applicable to the "uncertainty in time" and "uncertainty in energy" (including the rest mass energy mc2). When the mass is very large (such as a macroscopic object), the uncertainties and thus the quantum effect become very small, classical physics is applicable once more.

In classical physics (appliable to macroscopic phenomena), empty space-time is called the vacuum. The classical vacuum is utterly featureless. However, in quantum mechanics (appliable to microscopic phenomena), the vacuum is a much more complex entity. It is far from featureless and far from empty. The quantum vacuum is just one particular state of a quantum field (corresponding to some particles). It is the quantum mechanical state in which no field quanta are excited, that is, no particles are present. Hence, it is the "ground state" of the quantum field, the state of minimum energy. The picture on the left illustrates the kind of activities going on in a quantum vacuum. It shows particle pairs appear, lead a brief existence, and then annihilate one another in accordance with the Uncertainty Principle.

Quantum Fluctuations and Their Energy
Matt Strassler [August 29, 2013]
In this article I am going to tell you something about how quantum mechanics works, specifically the fascinating phenomenon known as “quantum fluctuations”, and how it applies in a quantum field theory, of which the Standard Model (the equations that we use to predict the behavior of the known elementary particles and forces) is an example.  A deep understanding of this phenomenon, and the energy associated with it, will lead us directly to confront what is certainly one of the most dramatic unsolved problem in science: the cosmological constant problem.  It will also lead us to the puzzle known as naturalness or the hierarchy problem, though I’ll explain that elsewhere.

An aside: in quantum field theory, quantum fluctuations are sometimes called, or attributed to, the “appearance and disappearance of two (or more) `virtual particles‘ “. This technical bit of jargon is unfortunate, as these things (whatever we choose to call them) are certainly not particles — for instance, they don’t have a definite mass — and also, more technically, because the notion of “a virtual particle” is only precisely defined in the  presence of relatively weak forces.
Fig. 1: Normal intuition would lead us to expect that anything like a marble sitting in anything like a bowl would sit quietly at the bottom. But a quantum mechanical particle in a trap of some sort will have a position and motion that are constantly fluctuating. These fluctuations have energy; the motion-energy of a quantum particle in a trap is never zero.

Quantum fluctuations are deeply tied to Heisenberg’s uncertainty principle. Here’s the classic, simplest example (Figure 1): if you put a marble at the bottom of a bowl, it will stay there indefinitely, as far as you can tell. That is what you’d expect, from daily experience.  And it would be true, in the absence of quantum mechanics. But if you put a very lightweight particle in a tiny bowl, or some other type of trap, you will discover it doesn’t sit at the bottom. If it did sit motionless at the bottom, it would violate the uncertainty principle — a principle which assures you can’t know exactly where the particle is (i.e., at the bottom) and how it’s moving (in this case, not moving at all) at the same moment.  You may think of this, imperfectly but usefully, as due to a sort of jitter which afflicts the particle and prevents it from settling down the way your intuition from marbles in bowls leads you to expect.  One useful aspect of this imperfect picture is that it gives you an intuitive idea that there might be energy associated with this jitter.

In quantum field theory — the quantum equations for fields, such as the electric field, there is a similar effect. Let me now explain it.

Fluctuations of Quantum Fields
Every elementary particle (I speak of real particles now) in our universe is a ripple — a small wave, the wave of smallest possible intensity — in a corresponding elementary quantum field (Figure 2). A W particle is a ripple in a W field; a photon [a particle of light, which you may think of as the dimmest possible flash] is a ripple in the electric field; an up quark is a ripple in the up quark field.

And if there are no particles around? Even in what we consider empty space, the fields are still there, sitting quietly in empty space, much as there’s water in the pond even if no wind or pebbles are making ripples on its surface, and there’s still air in the room even if there’s no sound.

Fig. 2: (Left) A particle may be viewed as a little ripple in a field, which away from any particles just sits quietly -- naively -- like the marble in the bottom of the bowl.  (Right) But in fact the value of the field at every point in space is constantly fluctuating, just as the particle in the bowl is always jittering.
Fig. 2: (Left) A particle may be viewed as a little ripple in a field, which away from any particles just sits quietly — naively — like the marble in the bottom of the bowl. (Right) But in fact the value of the field at every point in space is constantly fluctuating, just as the particle in the bowl is always jittering.

But here’s the thing: those fields are never entirely quiet. Quantum fields never quite maintain a constant value; their value at any point in space is always jittering around a bit. This jitter is called “quantum fluctuations”, and just as for the particle in the tiny bowl, it is a consequence of the famous “uncertainty principle” of Heisenberg.  (You can’t know a field’s value, and how it’s changing, at exactly the same time; your knowledge of at least one, and typically both, must inevitably be imperfect.)  Again, these quantum fluctuations are sometimes described as being due to two or more “virtual particles”, but this name really reflects a technical issue (i.e., how you can calculate the fluctuations’ properties using Feynman’s famous diagrams) more than it guides you as to how you should really think about them.

Obvious question: are you sure there are really quantum fluctuations for fields? Answer: Yes, though I won’t explain it now. One example: quantum fluctuations are known to cause the strengths of forces to drift as you measure them at shorter and shorter distances, and not only do we observe such drift in data, what we observe matches, to high precision, with what we calculate using the Standard Model.  This success confirms not only the presence of quantum fluctuations but also the detailed structure of the Standard Model, down to distances of about a millionth of a millionth of a millionth of a meter. Another example: the response of an electron to a magnetic field can be measured to about one part in a trillion; it can also be calculated, using the Standard Model, to about one part in a trillion, assuming the existence of these fluctuations of the known fields of nature. Amazingly, the measurement agrees with the Standard Model calculation.

Importantly, that jitter creates a certain amount of energy — a lot of energy. How much? The better your microscope (or particle accelerator), the more jitter you can detect, and the more energy you discover the jitter has. If you’d like to see how we estimate the amount of this energy, click here (sorry, page not yet written). If not, or if you’d just like to get the main point and then come back to study this estimate, just accept what I’m about to tell you.

The Energy of These Fluctuations and the Cosmological Constant
Let’s consider a box of size one meter by one meter by one meter, and ask: how much energy, roughly, do we calculate is inside the box due to the jitter in a single elementary field?  (See Figure 3.)

Calculation 1: Suppose, as our experimental measurements at the Large Hadron Collider [LHC]  suggest, that the Standard Model is a valid description of all processes that occur at distances of larger a millionth of a millionth of a millionth of a meter — let’s call this the “LHC-ish distance”, about 1/1000 the radius of a proton, because that’s roughly the scale the experiments at the LHC can probe — and processes involving elementary particle collisions with energies smaller than about 1000 times the proton‘s mass-energy [i.e. it’s E=mc² energy].  This energy is the typical mass-energy of the heaviest particle that we could hope to discover in the LHC’s proton-proton collisions, so let’s call it the “LHC-ish energy”.  Then the amount of energy in the fluctuations of each field in the Standard Model (say, for example, the electric field) is this: in every cube whose sides are an LHC-ish distance, there’s something like an LHC-ish energy inside.  In other words, the energy density is about one LHC-ish energy per LHC-ish volume.  Compare this with ordinary matter, whose energy density is a few proton or neutron mass-energies  (an atomic nucleus worth of mass-energy) for every atom, whose volume, since a proton or neutron is 100,000 times smaller in radius than an atom, is about 1,000,000,000,000,000 (a thousand million million) times larger than a proton’s volume.  (Remember the atom is emptier, relatively speaking, than the solar system.) That means the energy density of quantum fluctuations of the electric field is roughly a million million million times more than ordinary matter, and so the mass-energy in fluctuations of the electric field inside a cube one meter on a side is about a million million million times larger than the mass-energy stored in a cube of solid brick, one meter on each side. How much energy is that? Easily enough to blow up a planet, or even a star! In fact, it’s comparable to the total mass-energy  of the sun. (Egad!) Now, one can’t release this energy from the vacuum of space, for good or evil — so don’t worry about its presence, it’s not directly dangerous.  But this is already enough to raise the specter of the cosmological constant problem.

Calculation 2: Suppose, as is relevant for the question of the hierarchy problem and the naturalness of the universe, that the Standard Model describes all particle physics processes down to the length scale where gravity becomes a strong force — the so-called Planck length, which is another thousand million million times smaller than the distance considered in Calculation 1. Then the amount of energy from fluctuations of the electric field inside a cube a meter on all sides is larger than in Calculation 1 by
  • (1,000,000,000,000,000)4 = 1 with 60 zeroes after it.

If you take this number and multiply by the number given in Calculation 1, you get easily enough energy to blow up every star in every galaxy in the visible part of the universe… many many many many times over. And that’s how much energy there is in every single cubic meter — if the Standard Model is correct for physical processes of size all the way down to the Planck length.
Fig. 2:
Fig. 3: The amount of energy due to quantum fluctuations of any field is enormous. In the Standard Model, the total energy in a meter of empty space is vastly more (Calculation 1) than in a cubic meter of ordinary matter; and there’s even unimaginably more (Calculation 2) if the Standard Model is valid all the way down to the Planck length. But the universe’s slow expansion (Measurement 0) suggests the total energy of a cube empty space (often called the `dark energy’) is much much less than that stored in a cube of ordinary matter. This is the cosmological constant problem: a profound apparent failure of the otherwise highly successful equations used in particle physics and gravity.

More generally, if the Standard Model (or any typical quantum field theory without special symmetries) is valid down to a distance scale L, the energy of the fluctuations in a cube of size L³ is approximately hc/L (for each field), where h is Planck’s quantum mechanics constant and c is the universal speed limit, known usually as “the speed of light”.  That means the energy density is roughly hc/L4 — if L decreases by a factor of 10, the energy density goes up by a factor of 10,000! That’s why these numbers in Calculations 1 and 2 are so darn big.

These statements must really seem bizarre to you. They are bizarre, but hey — quantum physics is bizarre in many ways. Moreover, neither quantum mechanics in general, nor quantum field theory in particular, have previously led us astray. As I mentioned earlier, we have plenty of evidence that the very basic calculations like the ones required here work beautifully in quantum field theory. The fact that there are quantum fluctuations, with associated energy, is so deeply built into quantum mechanics that to declare it simply to be false requires you to explain a whole library of experimental results for which quantum mechanics gave correct predictions. So as scientists we have no choice but to take our calculation very seriously, and to try to understand it.

A couple of obvious questions you may ask: Why can’t we easily tell whether all that energy is there or not?  Why doesn’t all this vast amount of energy have an enormous effect on ordinary matter, including us?!   Answer, part 1: Because there’s the same amount of energy in every cubic meter of space (Figure 4), both inside and outside every box you can draw.  An analogy: there’s air pressure inside a house, but it doesn’t cause the house to explode as long as there’s equal air pressure outside the house. Similarly, the fact that this energy density of tiny quantum fluctuations is constant throughout space and time means that there’s no effect on objects that sit within it and move through it. Only changes in energy from place to place, or over time, will affect particles, and the atoms that are made from such particles, and people and planets made from such atoms. And indeed, this energy from quantum fluctuations is the same everywhere, always, so it’s impossible to feel it, or be pushed around by it, or release it for good or evil.

Fig. 3: The energy stored in empty space has no effect on ordinary objects because it's the same everywhere, at all times.  However, gravity (in Einstein's theory) does respond to a constant energy density; it changes how the universe expands.
Fig. 4: The energy stored in empty space has no effect on ordinary objects because it’s the same everywhere, at all times. However, gravity (in Einstein’s theory) does respond to a constant energy density; it changes how the universe expands.

However! Answer, part 2: While in Newton’s law of gravity, where gravity pulls on mass, this energy of empty space will have no effect, the same is not true in Einstein’s version, where gravity pulls on energy and momentum. Whether calculation 1 is right, or calculation 2 is right, or something in between, such a vast amount of energy in every cube of space — what is often called “dark energy” — would cause the universe to expand with extreme speed! (In fact, this is the mechanism behind “cosmic inflation”, which is a phase that the universe may have gone through long ago, making it the rather uniform place we see today.) The fact that the universe is not expanding at tremendous speed implies that the energy density of space should be vastly less than the mass-density of ordinary matter, instead of vastly greater. In every cubic meter of empty space there is only about one atom’s mass-energy, whereas in a cube of bricks the mass-energy is that of its huge number of atoms —  the number being about 1 with 30 zeroes after it.  The fact that there is apparently so little energy density in empty space, despite all the energy we calculate should be there from quantum fluctuations of the fields we already know about, is the mother and father of all great puzzles in particle physics: the cosmological constant problem.

Next obvious question: are you sure the quantum fluctuations really have energy, or is it possible they don’t, thereby eliminating the cosmological constant problem? Answer: Yes, I’m sure quantum fluctuations do have energy; it’s what’s called zero-point energy, and it’s completely fundamental to quantum mechanics, and due yet again to the uncertainty principle.  And this can be checked: n a clever experiment, the energy in a small region can be made to have a measurable impact called the “Casimir effect”, which was predicted in the 1940s, first observed in the 1970s and tested more carefully in the 1990s.  [There is some controversy about whether this is really relevant to the question, however.]

The cosmological constant problem is a very serious one. We know, experimentally, that the universe is not expanding at a spectacular rate; it’s expanding rather slowly; that’s Measurement 0 in Figure 3.  So
  • either this calculation (even calculation 1, which doesn’t assume anything that we don’t know experimentally about the Standard Model) is wrong, somehow, and the energy simply isn’t there, or
  • the effect of this energy on the universe’s expansion is not what we think, because our understanding of gravity is wrong, or
  • it’s a correct calculation, but it answers the wrong question in some way we don’t understand.

Nobody knows for sure.  I’ll talk about possible solutions to this problem in a separate article on the cosmological constant.  But let me mention one solution that is interesting but certainly doesn’t work, because it will be relevant elsewhere.

Could The Energy from Different Fields Cancel Out?
Now here’s a cute idea for getting rid of all that energy. It turns out that

So maybe, even though each field’s energy is huge, when you add up the energy from all the fields, the total energy is zero — or at least really tiny?

Well, you can do this calculation, and in the Standard Model you’ll see it doesn’t work; there are way too many fermions, and there should be a huge negative energy in empty space.

One cool thing about the speculative theory called “supersymmetry” is that it forces you to add exactly the right particles (a “superpartner particle” for every known type of particle) so that you get this cancellation automatically! In fact, it’s the only type of speculative theory currently known to humans in which this would happen.

Unfortunately, it doesn’t actually solve the cosmological constant problem. If supersymmetry isn’t explicitly manifest [and in our world it can’t be — the known particles would in this case have had identical masses to their hypothetical superpartner particles and would have been discovered long ago] then the cancellation is only partial.  And this partial cancellation, which could invalidate Calculation 2, still at best leaves you with the huge amount of energy density mentioned in Calculation 1.  As noted in Figure 3, that gigantic amount of energy density is still enough to make the universe behave very differently from what we observe, unless there’s something wrong with Einstein’s theory of gravity.

In short, at the present time, no one knows a clever way to automatically make the energy density from the fluctuations of different fields cancel out in a world that, down to LHC-ish distances, is described by the Standard Model. In fact, no one knows how to do it in any even slightly non-supersymmetric quantum field theory (and even then, combining supersymmetry with gravity tends to reintroduce the problem.)

To say this another way: even though it is possible that there is a special cancellation between the boson fields of nature and the fermion fields of nature, it appears that such a cancellation could only occur by accident, and in only a very tiny tiny tiny fraction of quantum field theories, or of quantum theories of any type (including string theory).  Thus, only a tiny tiny tiny fraction of imaginable universes would even vaguely resemble our own (or at least, the part of our own that we can observe with our eyes and telescopes).  In this sense, the cosmological constant is a problem of “naturalness”, as particle physicists and their colleagues use the term: because it has so little dark energy in it compared to what we’d expect, the universe we live in appears to be highly non-generic, non-typical one.

[As I mentioned at the beginning, there is a second big problem associated with quantum fluctuations which you may wish to read about.  It is known from different points of view as the Standard Model’s naturalness problem or the hierarchy problem. ]

Quantum Fluctuations May Kill Big Bang Evangelism
Many Christians today embrace the big bang theory as an avenue for evangelism. They reason that a big bang origin of the universe naturally leads one to conclude that there must be a Creator, thus opening the door for sharing the gospel. However, there is a growing belief that a quantum fluctuation gave rise to the universe apart from God. This belief is based upon several speculative and probably incorrect ideas concerning physics, but it appears to be the direction that big bang cosmogony is headed. If big bang evangelism ever was effective, its window is rapidly closing.

The Reason for Belief in an Eternal Universe
Christians who believe the big bang model frequently argue that if the universe had an origin, then there must be a transcendent Creator. Indeed, the implication of a Creator was the main reason why so many cosmologists and astronomers opposed the big bang model for many years in the middle of the 20th century. Many scientists chose to believe in an eternal universe rather than the big bang origin primarily because an eternal universe avoids the need of a Creator. However, the 1965 discovery of the cosmic microwave background convinced most scientists that the big bang was the correct origin model of the universe. Consequently, the big bang model has been the dominant cosmogony for nearly a half century, so today few people are aware of that early opposition.

Even though the big bang model now enjoys wide acceptance, the need for a Creator has not gone away. To counter this problem, cosmologists and physicists have devised arguments that supposedly show how the big bang could have happened apart from a Creator. Over the years, those who criticize recent creationists have chastised us for not publishing our work on creation in what they consider legitimate scientific journals. The critics claim that when creationists write popular-level books, creationists are attempting to circumvent the scientific process. Interestingly, very little of the supposed mechanisms of how the universe came into existence spontaneously is published in scientific journals either. Instead, atheist scientists write their thoughts on this subject in popular-level books. A recent example of this is Lawrence Krauss’ 2012 book, A Universe from Nothing. In this book, Krauss draws upon topics that have been published in scientific journals to make some conclusions about the origin of the universe apart from a Creator, but those conclusions were made in the book, not in the scientific literature.

Enter Quantum Fluctuations
The question arises whether any articles have been written in the traditional scientific journals on the spontaneous appearance of the universe. One possibility is Tryon (1973). Tryon published in Nature, a prestigious science journal, but his brief article reads more like a letter or opinion piece, so it is doubtful that it went through any sort of rigorous peer review. Apparently, Tryon was the first to suggest that the universe began in a quantum fluctuation. Perhaps a better example would be the more recent, detailed paper on the supposed quantum fluctuation origin of the universe by Stenger (1989).

What is a quantum fluctuation? In classical physics, we know that energy is conserved, that is, that energy can neither be created nor destroyed. Our understanding of the conservation of energy comes from countless experiments of localized parts of the universe, but, presumably, the law of conservation of energy applies to the universe as a whole. Therefore, it would seem that the sudden appearance of energy, as required by the big bang model, would violate the conservation of energy. However, many physicists think that the Heisenberg uncertainty principle (HUP) offers a way around this problem. The HUP is an aspect of quantum mechanics, the physics of small systems, such as atoms and sub-atomic particles. The HUP places a limit on how well we can know information about a small particle. One formulation of the HUP relates our uncertainty in knowing a particle’s energy to the uncertainty in the measurement of time that the particle occupies the measured energy . Let ΔE represent the uncertainty in the amount of energy and∆t represent the uncertainty in the time. Then the product ΔE∆t is approximately equal to ħ, where ħ = h/2π, and h is Planck’s constant. Planck’s constant has the value 6.626 x 10-34 Joule-second. Notice that Planck’s constant has the appropriate units of energy and time. Planck’s constant is very small, so the uncertainties are vanishingly small on a macroscopic scale. That is why the HUP is not observable in the macroscopic world. However, on the scale of subatomic particles, the uncertainties can be large compared to the quantities involved, so the consequences of the HUP can be significant on the microscopic scale.

But Does This Mechanism Work?
There are certain experimental results that demonstrate the HUP, so the HUP is a well-accepted phenomenon in quantum mechanics. However, a problem arises when physicists attempt to expand the meaning and application of the HUP to violations of the conservation of energy. This expansion is the teaching that violations of energy conservation are allowed as long as they do not last very long. That is, if ΔE is the violation of the conservation of energy over some time ∆t, then such violations are permitted as long as the product ΔE∆t is less than ħ. To support this interpretation, physicists often refer to certain experiments where they infer that pairs of virtual particles pop into existence before popping back out of existence. Albert Einstein showed with his famous E = mc2 equation that matter and energy are equivalent things. Hence, the appearance of particles would violate the law of conservation of energy, unless the pairs of particles exist for a very short period of time. While this is a common interpretation of the HUP, it is controversial. For instance, Bunge (1970) has called virtual particles fictitious and argued that quantum field theory can explain these experiments without appeal to virtual particles. Or consider the comments of David Griffiths, a physicist with two well-respected textbooks in relevant fields. In one text he wrote this:

It is often said that the uncertainty principle means energy is not strictly conserved in quantum mechanics—that you’re allowed to “borrow” energy, as long as you “pay it back” in a time; the greater the violation, the briefer the period over which it can occur. Now, there are many legitimate readings of the energy-time uncertainty principle, but this is not one of them. Nowhere does quantum mechanics license violation of energy conservation, and certainly no such authorization entered into the derivation of Equation 3.74.(Griffiths 2005)

And in another text he wrote the following:
In special relativity, the energy E, momentum, p, and mass m of a free particle are related by the equation E2-p2c2 =m2c4. But for a virtual particle E2 – p2c2 can take on any value. Many authors interpret this to mean that virtual processes violate conservation of energy (see Problem 1.2). Personally, I consider this misleading, at best. Energy is always conserved. (Griffiths, 2008)

Negative Energy
Dismissing these objections, many physicists and cosmologists want to apply this approach to the entire universe. They ask, “What if the sum of the energy in the universe is zero?” They conclude that if the energy of the universe is exactly equal to zero, then the universe could have popped into existence without violating the conservation of energy and could continue to exist for billions of years. In his essay, Tryon (1973) famously quipped that “our universe is simply one of those things which happen from time to time.” This is the ultimate evolutionary theory, because the universe itself is just a sort of accident; there was no cause, and so there is no need of God.

Besides relying upon a very questionable application of the HUP, this approach also requires that the total energy of the universe is zero. There is a tremendous amount of energy in the universe. Much energy is in the form of light or other electromagnetic radiation. Quantum mechanically, we think of radiation consisting of particles called photons. Each photon has energy E = hν, where ν is the frequency of the photon. Since both h and ν are positive, all energy of electromagnetic radiation is positive. Matter in the universe has an equivalent energy given by the famous Einstein equation E = mc2, where m is mass and c is the speed of light. Since c is a large number that is squared, matter in the universe has considerable energy (this is why nuclear power is so efficient). Since m and c are positive numbers, the total energy of matter in the universe is positive as well. Together, the mass and radiation energy of the universe is considerably positive, so for the universe to be the result of a quantum fluctuation, there must be a tremendous amount of negative energy to counterbalance the positive energy.

Where might this negative energy be? In physics, the only negative energies are those encountered with potential energies. Indeed, Tryon used gravitational potential energy in the general form –GmM/R to estimate the total gravitational potential energy of the universe. Using values then current (circa 1973), Tryon found that gravitational potential energy and the energy of matter were roughly equivalent, from which he concluded that the universe had zero energy. However, potential energies are zero only if we choose an appropriate reference point to make them so (the mathematics is simpler this way). In classical physics, the choice of reference point is arbitrary, and if we choose a different reference point, all potential energies could be positive. Hence, in an absolute sense, one cannot so easily make the energy of the universe zero. However, some physicists have argued that in non-classical physics this is possible (Berman 2009) or have put forth theories of how certain fields may be present in the universe that may require negative potential energies. Indeed, the entire motivation for this sort of approach appears to be the bias against the possibility of a Creator rather than some formal requirement based upon observation of the universe or known laws of physics.


Setting this difficulty aside for now, the manner in which a quantum fluctuation could operate is not totally agreed upon. One possibility is to argue that the universe appeared truly out of nothing in a manner consistent with itself. In a world without quantum fluctuations, the sudden appearance of energy would violate a basic property of the universe, the conservation of energy, so a universe governed by classical physics without the Heisenberg Uncertainty Principle cannot spontaneously appear out of nothing. However, a universe governed by quantum mechanics allows for quantum fluctuations, so the universe could have arisen in this manner. Another possibility is to argue that the big bang was preceded by . . . well, nothing. But does nothing truly exist? Quantum mechanically, a vacuum totally devoid of matter isn’t so empty. As previously mentioned, this whole line of reasoning relies upon a particular interpretation of the HUP. This same interpretation requires that virtual particles spontaneously pop into and out of existence. Those virtual particles amount to a form of energy. If this vacuum that preceded the big bang had more energy than the current universe, then, since physical systems naturally go from higher to lower energy, the big bang inevitably followed that earlier, higher energy state. However, Tryon (1973) hinted at the current thinking on the subject when he suggested that the universe appeared, not out of nothing, but in “. . . the vacuum of some larger space in which our Universe is imbedded.” Now many astronomers and cosmologists think that our universe is just one universe in a vast multiverse consisting of myriads of other universes. In this view, our universe was spawned by a hypothetical process called inflation. This process is supposedly spawning even more universes even now in a supposedly never-ending process. The multiverse is the totality of all these past and future universes. This amounts to a return to the eternal universe, albeit on a much grander scale. As previously mentioned, an eternal universe has no place for God.

Notice that these things are discussed in popular-level books, not in the scientific literature, so apparently evolutionists are not held to the same standard that creationists are. This sort of reasoning may seem silly or even bizarre to most people, but such ideas have gained tremendous traction among physicists in recent years. At first, these were just wild ideas that physicists informally discussed, followed by more formal discussions in colloquia, followed by brief mentions in popular-level books. The statements in books eventually were expanded to the point that they became the main focus of books. For instance, nearly 30 years before Krauss published his book, James Trefil (1983, pp. 203–208) briefly discussed such ideas in his book, The Moment of Creation. Halfway between, Before the Beginning: Our Universe and Others, a book by Marin Rees (1997), took a decidedly less tentative approach. While Krauss’ recent book appears more definite, most readers may not notice his frequent use of qualifying terms, such as “could,” “might,” and “may.” In the near future we can expect physicists, astronomers, and cosmologists to take a much more forceful attitude in insisting that it is as indisputable as gravity that a quantum fluctuation gave rise to the universe.

There are at least three serious logical problems with this entire line of reasoning:
  1. Quantum mechanics implicitly assumes the existence of time and space, so how can the laws of quantum mechanics create time and space?
  2. The only way that we know quantum mechanics is (at least approximately) correct is because we can do experiments and make observations to verify its predictions. Even if we accepted at face value the claim that QM allows particles to “pop” into and out of existence, who has ever observed a universe popping into existence?
  3. Point #2 is one of the big logical problems with the claim that the laws of physics can explain the creation of the universe. These laws have only been observed to be applicable within our universe. We thus have zero justification for believing that they would apply “outside” the universe.

Of course, these musings demonstrate the futility of man’s thinking apart from God. As the Apostle Paul warned in his epistle to the Romans (1:21–22, KJV),

Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. Professing themselves to be wise, they became fools. . . .

Unfortunately, many Christians embrace the big bang as evidence of the God of the Bible, and thus they have wedded the big bang model to their apologetics. Often their motivation is to bring people to salvation, reasoning that the big bang model shows that there must be a Creator, and so people will want to investigate who God is. However, people who take this approach fail to grasp the significance of these new developments within the big bang model. Lost souls who follow the latest pronouncements of scientists about the big bang are inclined to take those scientists’ opinions about there being no need for a Creator as well. While the motivation for evangelism of those Christians who accept the big bang is commendable, their approach is doomed to failure as the big bang model continues to assume a more atheistic bent.

Answers in Genesis stands for the authority of Scripture, so we start with the Bible when interpreting science rather than starting with the pronouncements of fallible scientists to interpret the Bible. We recognize that there are scientific problems with the big bang model (see “Does the Big Bang Fit with the Bible?”), but, more importantly, there are numerous biblical problems with the big bang model.

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