# Stephen Hawking explains the universe

I shall have to turn on my television Sunday evening (7 or 8pm, depending on where in the US you are). Stephen Hawking will be on the Discovery Channel to answer the question, “Is There a Creator?” — I’m pretty sure he’s going to answer “no.”

Q: First, we wonder if you could comment on why you are tackling the existence of God question?

A: I think Science can explain the Universe without the need for God.

Q. What problems you are working on now, and what do you see as the big questions in theoretical physics?

A: I’m working on the question, why is there something rather than nothing, why are the laws of physics what they are.

If that last bit has you curious, here’s a teaser:

Essentially on “Is There A Creator?,” Hawking notes that on the sub-atomic scale, particles are seen in experiments to appear from nowhere. And since the Big Bang started out smaller than an atom, similarly the universe likely “popped into existence without violating the known laws of Nature,” he says. Nothing created the universe, so in his view there was no need for a creator. That is his explanation for “why there is something rather than nothing.”

1. Super-smart… I feel dumb in comparison.

2. Richard Eis says

But who’s pushing the atoms into our universe then!!1!!!

Like pushing peanuts into the monkey cage.

3. says

Damn. I don’t get the Discovery Channel (which we have in Canada, but I don’t know how different the programming is).
I’ll be seeing Wicked tonight however. Though I don’t know if learning how the Wicked Witch of the West came into being quite comes up to the level of learning how the universe came to be, but the music will be fantastic…

4. daveau says

The commercials for this program almost look like it’s a religious program, and I was planning on skipping it. You may have changed my mind on this. 7:00 Central you say?

5. says

But who’s pushing the atoms into our universe then!!1!!!

Actually it’s not atoms, but subatomic particles, that pop into existence. This happens in a quantum vacuum, and the particles normally cancel one another out within a tiny timescale.

http://en.wikipedia.org/wiki/Virtual_particle

6. mikerattlesnake says

I appreciate Hawking’s work, but it seems he has gone downhill as a science communicator in recent years. I feel bad saying it, but I just feel like he doesn’t get his point across very well. It very well may be a direct result of his disability, and if so I don’t fault him at all, I just wish someone more eloquent was helping him out.

7. Audley Z. Darkheart, purveyor of candy and lies says

You know, I would be highly surprised and saddened if Hawking did think there was a need for a creator.

8. Sastra says

The “why is there something other than nothing?” question isn’t really a real question. It’s a trick question. Hawking can’t answer it by citing the laws of physics because a determined questioner can always move the question back to “so why does natural law allow something to come from nothing?” And so it goes.

At some point you simply have to terminate into some sort of brute fact. You can agree that this end-point is arbitrary or you can argue that there is something self-evident, necessary, or non-reductive about this Brute Fact.

Nature. Existence. Being. Reality.

But not “God” — because “God” has too many attributes to make itself into an irreducible source. It has mind-like aspects, for one thing: intentions, desires, emotions, goals, values, and/or thoughts. Those have to be supported by evidence, so we can easily imagine a universe or cosmos without God. (We also learned and thus now know that minds evolved, and are untimately physical — not the other way around.) “Why is there God rather than no God?” is a much more complicated, advanced, and controversial question than a more basic “why is there something rather than nothing?”

In real life, as we peel away the layers of explanation we get more and more basic and mindless and simple: matter, energy, quarks, strings, branes. But our tendency is to rebel against the idea that mind is anything like matter. Mind is too significant to have come out of things that weren’t at all mindlike. We instead think of mind as more basic than matter. Simpler; no “parts.”

So I think the reason people think “God” is a satisfactory termination point for this endless series of “why” questions is because God provides a psychological reason — and we humans like psychological reasons. They feel familiar to us because those are the kinds of reasons we use and find interesting. “Why is there something rather than nothing?” feels as if it’s been answered by saying “Because Someone wanted it that way.”

Oh, okay. Psychology. Personhood. We form the cosmos in our own image and treat it like a person. A mind trick — which thus “answers” a trick question.

9. particles are seen in experiments to appear from nowhere.

Say, that reminds me of a question I had that perhaps someone here can answer. Regarding cause and effect – would it be accurate to say that radioactive decay has no “cause”? Does it “just happen”? I know we can say that a particular atom will have a certain probability of decaying within a certain time, but that’s not a cause/effect relationship, is it?

Obviously, I am asking this because of the old “there is no effect without a cause” chestnut.

10. Non-Biblical Paul says

This should be worthwhile, I hope they give him at least 41 minutes to tackle the question, instead of a 5-10 minute segment.

11. ACN says

Radioactive decay is not caused by anything. It is a purely probabilistic phenomena with a characteristic exponential decay parameter for different species and decay modes.

12. drdale says

“…would it be accurate to say that radioactive decay has no “cause”? Does it “just happen”? I know we can say that a particular atom will have a certain probability of decaying within a certain time, but that’s not a cause/effect relationship, is it?”

“Radioactive decay is not caused by anything. It is a purely probabilistic phenomena with a characteristic exponential decay parameter for different species and decay modes.”

The first passage indicates that radioactive atoms will decay is probablistic and the concluding statement that radioactive decay is not caused by anything. Therefore, a better question is why is there radioactive decay, i.e. what makes an atom unstable. More to the point of the question, since the atom has this “unstable” existence where is the tipping point and what causes it, that results in radiation.

Based on this question, stating that the phenomenon is just probability is lacking. I don’t know the answer to this question.

13. SteveM says

I appreciate Hawking’s work, but it seems he has gone downhill as a science communicator in recent years. I feel bad saying it, but I just feel like he doesn’t get his point across very well. It very well may be a direct result of his disability, and if so I don’t fault him at all, I just wish someone more eloquent was helping him out.

I think it unlikely but Brian Cox would be the perfect co-host for Hawking. His “Wonders of the Universe” (Science Channel)is a fantastic program with profound appreciation for physics explaining everything. He was recently a guest of Colbert and gave a perfect response to Colbert’s question about the “truth” of physics (Whether he’d be willing to be told the laws we currently understand are all wrong)He said, between laughs, that science is always open to be told wrong, that is the purpose of science.

14. stvs says

Here’s some scientific background and links on universe ex nihilo theories, a background that isn’t presented widely enough, even at scienceblogs that address the subject specifically.

Guth’s Inflationary Universe is a must-read, in which Guth explains ex nihilo theories with the colorful statement:

The question of the origin of the matter in the universe is no longer thought to be beyond the range of science—everything can be created from nothing … it is fair to say that the universe is the ultimate free lunch.

Guth provides technical reasons for this claim:

Now we can return to a key question: How is there any hope that the creation of the universe might be described by physical laws consistent with energy conservations? Answer: the energy stored in the gravitational field is represented by a negative number! … The immense energy that we observe in the form of matter can be canceled by a negative contribution of equal magnitude, coming from the gravitational field. There is no limit to the magnitude of energy energy in the gravitational field, and hence no limit to the amount of matter/energy it can cancel. For the reader interested in learning why the energy of a gravitational field is negative, the argument is presented in Appendix A.

Guth goes on to explain a simple argument for all this that if you grasp, you will understand a fact of gravity that evaded Newton. Unfortunately, Google books doesn’t have Appendix A online.

Guth’s technical explanation above is what is meant by the nontechnical, poetic description, like Hawking’s: “Because there is a law like gravity, the universe can and will create itself from nothing.”

Here are some pointers to a quick technical explanation of the creation of a universe from literally nothing subject to the laws of quantum mechanics.

A technical account of the universe ex nihilo, following Vilenkin, “Creation of universes from nothing”. Physics Letters B Volume 117, Issues 1-2, 4 November 1982, Pages 25-28. Available here.

1. Observe the Friedmann–Lemaître–Robertson–Walker metric for universal expansion:

ds² = dt² – a(t)|dx

This is the space-time geometry with the spatial scale term a(t) describing the growth/contraction of the universe. This is Vilenkin’s equation (2).

2. Solve the evolution equation:

a(t) = (1/H)cosh(Ht)

where H² = (8π/3)Gρ is the Hubble parameter.

This is Vilenkin’s equation (3). So far, there is no explanation of a universe from nothing because the de Sitter space isn’t nothing, as everyone agrees.

3. Observe that at t = 0, the physics has the same form as a potential barrier, for which it is known that quantum tunneling is possible. The description of quantum tunneling involves a transformation tit, with i² = –1.

Now the evolution equation is

a(t) = (1/H)cos(Ht) [the cosine "cos", not the hyperbolic cosine "cosh"]

valid for |t| < π/2/H. This is Vilenkin’s equation (5). Space-Time is simply the 4-sphere, a compact, i.e, bounded space. At the scale a(t) = 0, this space is literally nothing. No space-time, no energy, no particles. Nothing. The interpretation of (5) is quantum tunneling from literally nothing to de Sitter space, the universe as we know it. See Figure 1a in Vilenkin’s paper for a depiction of the creation of the universe from nothing using this explanation.

Vilenkin says in the paper, “A cosmological model is proposed in which the universe is created by quantum tunneling from literally nothing into a de Sitter space. After the tunneling, the model evolves along the lines of the inflationary scenario. This model does not have a big-bang singularity and does not require any initial or boundary conditions. … In this paper I would like to suggest a new cosmological scenario in which the universe is spontaneously created from literally nothing, and which is free from the difficulties I mentioned in the preceding paragraph. This scenario does not require any changes in the fundamental equations of physics; it only gives a new interpretation to a well-known cosmological solution. … The concept of the universe being created from nothing is a crazy one. To help the reader make peace with this concept, I would like to give an example of a compact instanton in a more familiar setting. …”

This is what physicists mean by “nothing”. Nonexistent space-time, subject to the laws of quantum mechanics.

Guth provides a nontechnical explanation:

Alexander Vilenkin … suggested that the universe was created by quantum processes starting from “literally nothing,” meaning not only the absence of matter, but the absence of space and time as well. This concept of absolute nothingness is hard to understand, because we are accustomed to thinking of space as an immutable background which could not possibly be removed. Just as a fish could not imagine the absence of water, we cannot imagine a situation devoid of space and time. At the risk of trying to illuminate the abstruse with the obscure, I mention that one way to understand absolute nothingness is to imagine a closed universe, which has a finite volume, and then imagine decreasing the volume to zero. In any case, whether one can visualize it or not, Vilenkin showed that the concept of absolute nothingness is at least mathematically well-defined, and can be used as a starting point for theories of creation.

15. The Very Reverend Battleaxe of Knowledge says

I appreciate Hawking’s work, but it seems he has gone downhill as a science communicator in recent years. I feel bad saying it, but I just feel like he doesn’t get his point across very well. It very well may be a direct result of his disability, and if so I don’t fault him at all, I just wish someone more eloquent was helping him out.

Have you ever looked at any of those huge books he edited of original historic scientific works? Like A Stubbornly Persistent Illusion or God Created the Integers or On the Shoulders of Giants? There are like three or four typos per line! I’ve never seen anything like it. It’s as if everyone feels too bad to edit anything he writes.

16. andyo says

After that, this will air, with Sean Carrol and Paul Davies on the panel. Looking at the others, seems to me a bit like another “Dentists vs. tootheologists” kind of thing.

17. Kevin NYC says

HEY! hello! great to see you guys have a new site..

good luck

18. some Matt or other says

I’ve always interpreted the “radioactive decay has no cause” claim to be about the specific timing of emission. Meaning, there is no apparent cause for a given particle to fly off at this exact moment versus that exact moment; it’s only when you step back and look at multiple emissions over time that a probabilistic pattern emerges. But the decay itself is driven by a “cause”: the imbalance of forces in an atom with a skewed ratio of protons to neutrons.

I’m no physicist – not even a physics student, except in the most casual sense – so I could be totally wrong about that. But that’s how I’ve understood the concept.

As for Hawkings’ claim, I’m inclined towards the turtles-all-the-way-down skepticism that others have already expressed. If Hawkings really is using virtual particles as the evidence for creation ex nihilo, then the obvious problem there is that they have only been observed within our spacetime framework, which is not “nothing.” But this reply to the sister post on ScienceBlogs describes how it has been mathematically demonstrated that quantum tunneling could create our universe from absolute, literal nothingness. Of course the math is waaaaaaaaaaaaay over my head, and I don’t know how other physicists have reacted to it, but it seems reasonable to me that this is what Hawkings is talking about when he says that the universe could’ve “popped into existence without violating the known laws of Nature.” The problem there – the next turtle, if you will – is why the rules of quantum tunneling would exist in the absence of all else, but at least Hawkings seems to be aware of this problem when he says he is “working on the question, why is there something rather than nothing, why are the laws of physics what they are.”

Another already-expressed thought that I’ll echo is that I think Hawkings is a poor communicator of these ideas. I’ve been unimpressed since A Brief History of Time, which felt to me like it had sentences missing because he would jump from setup to conclusion so quickly and unsupportedly. Honestly, I don’t even know why he puts the effort into public discourse anymore. Maybe no one around him is willing to tell him how bad he is at it.

19. Alex says

@stvs

This fancy place does have latex support, you know? ;)
Just type \$latex blabla \$ without the backslashes. Just in case you want to further delve into the blasphemous theories this belgian priest has invented ;)

@Occam’s Blunt Instrument

The metaphysical question whether radioactive decay has a cause is directly linked to the question which interpretation of quantum mechanics you follow. In the end though, it looks like the decay is entirely probabilistic. Then there’s a second, apparently separate question: why is there a decay rather than no decay.Within the framework of quantum physics this is easy to answer – in terms of quantum mechanical states, the state containing a nucleus, and the state containing the decayed remains, have an overlap via the energy operator which determines the time evolution of the world, or, as a cheap excuse to bring out some more latex (yeah!),

$\langle \mbox{nucleus}|\mathcal{H}|\mbox{decay products}\rangle \neq 0$.

So the quesiton is, why is $\mathcal{H}$, which encodes all the dynamics of particles within the universe, the way it is. That boils down to the choice of fundamental constants of nature, which is an unsolved problem.

Now, if you want to apply this to the beginning of the universe, even smart people like Hawking will hit the problem that Sastra has eloquently presented above. The “why is there something rather than nothing” question makes only sense on a superficial level, if you define “something” as the particles we observe today, and “nothing” very loosely as a maximally simple, vacuum-like state.

What he then can argue using his quantum cosmology machinery is that, potentially, all the mess arose from a very, very simple state, one that is so simple that noone should even be tempted to invoke a personal god figure.

A very featureless state that you can in principle write down on a coaster, and from which the complex looking laws of physics we have today, and from that automatically all the matter and stuff we observe including us, could have arisen by the simple principles of quantum theory alone. If this is even remotely possible, we have achieved something profound in my opinion, since now the only remaining question – “where did the framework come from in which this simple initial vacuum state exists at all” – is so far removed from the “why are we here” or “who am I” question that a personal creator figure isn’t even a good psychological explanation any more.

20. Alex says

some Matt or other,

describes how it has been mathematically demonstrated that quantum tunneling could create our universe from absolute, literal nothingness.

I think without having read the post in detail, we can dismiss the claim about “literal nothingness” out of hand. If they calculate tunneling amplitudes, they do start with a quantum mechanical state, maybe something like a vacuum state. That is most definitely not “nothingness”, much less “literal nothingness” ;)

21. stvs says

I’ve always interpreted the “radioactive decay has no cause” claim to be about the specific timing of emission

No. It means that cause doesn’t even make sense in the physical description of radioactive decay, which is presented by this Feynman diagram. Particles may take any continuous path through space-time—curved, loopy, even faster than light speed!—therefore, it doesn’t make sense to ask what “caused” the W boson any more than it makes sense to ask what “caused” the photon in electron repulsion. In fact, for the physics to work out with observations, it is necessary that particles be allowed to take any crazy path through space-time.

Feynman describes this all beautifully in his must-read popular book QED:

quantum electrodynamics, which looks at first like an absurd idea with no causality, no mechanism, and nothing real to it, produces effects that you are familiar with: light bouncing off a mirror, light bending when it goes from air into water, and light focused by a lens. It also produces other effects that you may or may not have seen, such as the diffraction grating and a number of other things. In fact, the theory continues to be successful at explaining every phenomenon of light. …
Another possible theory is that the photons have some kind of internal mechanism-”wheels” and “gears” inside that are turning in some way-so that when a photon is “aimed” just right, it goes through the glass, and when it’s not aimed right, it reflects. … The trouble with that theory is, it doesn’t agree with experiment … Try as we might to invent a reasonable theory that can explain how a photon “makes up its mind” whether to go through glass or bounce back, it is impossible to predict which way a given photon will go. Philosophers have said that if the same circumstances don’t always produce the same results, predictions are impossible and science will collapse. Here is a circumstance—identical photons are always coming down in the same direction to the same piece of glass—that produces different results. We cannot predict whether a given photon will arrive at A or B. All we can predict is that out of 100 photons that come down, an average of 4 will be reflected by the front surface. Does this mean that physics, a science of great exactitude, has been reduced to calculating only the probability of an event, and not predicting exactly what will happen? Yes. That’s a retreat, but that’s the way it is: Nature permits us to cal­culate only probabilities. Yet science has not collapsed. …
let’s calculate the probability that two electrons, at points 1 and 2 in space-time, end up at points 3 and 4 (see Fig. 59). … To make a more exact calculation that will agree more closely with the results of experiment, we must consider other ways this event could happen. For instance, for each of the two main ways the event can happen, one elec­tron could go charging off to some new and wonderful place and emit a photon (see Fig. 60). Meanwhile, the other electron could go to some other place and absorb the photon. Calculating the amplitude for the first of these new ways involves multiplying the amplitudes for: an electron goes from 1 to the new and wonderful place, S (where it emits a photon), and then goes from 5 to 3; the other electron goes from 2 to the other place, 6 (where it absorbs the photon), and then goes from 6 to 4. … But wait: positions 5 and 6 could be anywhere in space and time—yes, anywhere—and the arrows for all of those positions have to be calculated and added together. …
I would like to point out something about photons being emitted and absorbed: if point 6 is later than point 5, we might say that the photon was emitted at 5 and absorbed at 6 (see Fig. 61). If 6 is earlier than 5, we might prefer to say the photon was emitted at 6 and absorbed at 5, but we could just as well say that the photon is going backwards in time! However, we don’t have to worry about which way in space-time the photon went; it’s all included in the for­mula for P(5 to 6), and we say a photon was “exchanged.” Isn’t it beautiful how simple Nature is!

It is necessary that virtual particles exceed the speed-of-light to make the theory conform to measurements. A technical account of this fact is provided by Feynman and Weinberg:

Now here is a surprise: when we evaluate the amplitude, … we find that it cannot be zero … outside the light cone. This is very surprising: If you start a series of waves from a particular point they can not be confined to be inside the light cone if all the energies are positive. … In other words, there is an amplitude for particles to travel faster than the speed of light and no arrangement of super-position (with only positive energies) can get around that.
Elementary Particles and the Laws of Physics, pp. 8f

Also, both Gleick’s and especially Krauss’s biography of Feynman have nice popular treatments of the physics as well. Both are available in part at Google books—Krauss explains faster-than-light travel of virtual particles on page 133.

For those interested in technical references, I’d recommend Zee, Quantum Field Theory in a Nutshell. A graduate textbook, but a highly approachable and conversational one. You can skip over the equations on the first pass and just read the narrative. Especially recommended is the experimentally-motivated and simple commonsense “Zen-like” explanation for the abstract and bizarre path integral approach. It’s also breathtaking to see in Zee’s chapter “Field Theory Redux” nearly the entirety of known physical existence laid out and explained in a page and a half and four equations. Then in the chapter “The Magnetic Moment of the Electron”, Zee lays out two of the greatest contributions in the history of physics in three pages.

22. stvs says

The metaphysical question whether radioactive decay has a cause is directly linked to the question which interpretation of quantum mechanics you follow.

Not in the context we’ve been discussing, at least not yet. As far as we know, the path integral approach is the only game in town:

Bohmian mechanics does not account for phenomena such as particle creation and annihilation characteristic of quantum field theory. This is not an objection to Bohmian mechanics but merely a recognition that quantum field theory explains a great deal more than does nonrelativistic quantum mechanics, whether in orthodox or Bohmian form.
Stanford Encyclopedia, Bohmian Mechanics

23. To all of those who commented on my radioactive decay question, my thanks.

I took one semester of graduate-level physics back in 1984 and I figured that I’m hopelessly out of date. Feynman’s explanation pretty much matches my understanding – causality as the typical fundy interprets it does not apply to decay. This might be worth uploading next time some fundy tries the old “unmoved mover” argument, if I can get them to agree in advance that they’d admit they were wrong if I could offer an example of an effect that has no “cause” ;) At the very least it make them go away – for a long time – to wikipedia university.

24. Jay says

Every time I see Dr. Hawking I’m forced to wonder, why hasn’t anyone hooked him up to a Brain Computer Interface? Surely one of the great minds of our time could benefit from easier communication.

25. Hume's Ghost says

If radioactive decay is uncaused, then nothing caused the destruction of Hiroshima, because the explosion was the result of a cascading sequence of radioactive decays. But this is absurd, and violates our ordinary notion of causality.

This discussion assumes the Newtonian idea that causality is the same as determinism. But “cause” has always been a probabilistic term. For example, smoking causes cancer, but most smokers don’t get cancer. A cause is something that raises the probability of its effect – smoking raises your chances of getting cancer.

The laws of nature (plus the boundary conditions) fix the probabilities of events, including radioactive decay, and so determine what causes what. Schroedinger’s cat was killed by the vial of radioactive substance placed in the cage, and so Schroedinger caused the cat’s death (or not).

26. If radioactive decay is uncaused, then nothing caused the destruction of Hiroshima, because the explosion was the result of a cascading sequence of radioactive decays.

That was a chain reaction, not decay.

27. Hume's Ghost says

That was a chain reaction, not decay.

…a chain reaction that started with one or more radioactive decays. And each of the fission reactions in the chain is the (probabilistic) decay of an intermediate nucleus that is highly unstable.

28. …a chain reaction that started with one or more radioactive decays.

Oo I see what you did there.

29. Quintin Phillips says

We find it hard imagine material popping into existence but time just occurring is more easily accepted. Space and time are, in my opinion, more difficult to explain than matter.

30. Robert Byers says

Stephen Hawkings is truly to be respected as a strong man in living and working around his medical problem.
Yet can he say science can dismiss a need for a creator in matters of the universe when science(whatever that is) has not cured medical problems like his.
What’s more intellectually difficult?
Further I understand he’s famous but i don’t see myself what he has contributed in a great way to justify his ideas as more important then others.
What has he patented in ‘science’.
Wiki just mentions about ideas on black holes which surely are minor matters.
i don’t right now see why he should be in the lists of notable ‘scientists” of our times.
What has he discovered or invented or figured out?
This biblical creationist sees that the achievers in ‘science’ should have greater authority in these things then the rest. Even then just in their fields.

31. Wowbagger, Madman of Insleyfarne says

Robert Byers obviously hasn’t gotten any brighter during his incarceration.

32. consciousness razor says

Yet can he say science can dismiss a need for a creator in matters of the universe when science(whatever that is) has not cured medical problems like his.
What’s more intellectually difficult?

Hmm, so it goes something like this?
1) There exists disease X, for which we have not yet found a cure, if there is a cure.
2) There is a cure.
3) Scientific discoveries in separate fields occur in order of increasing “difficulty” as defined by an ignorant creobot.
4) Therefore, Jesus. Maybe.

I think you’re going to have to work on that argument a bit more.

Further I understand he’s famous but i don’t see myself what he has contributed in a great way to justify his ideas as more important then others.

A cosmologists ideas about cosmology aren’t more important than Biblical creationism, or some other set of myths? Surely, you jest.

What has he patented in ‘science’.
Wiki just mentions about ideas on black holes which surely are minor matters.
i don’t right now see why he should be in the lists of notable ‘scientists” of our times.

Why are ideas about black holes a minor matter? Because you don’t talk about them at church every week?

What has he discovered or invented or figured out?

Hawking radiation, which helps us figure out things like this:

For a black hole of one solar mass (M = 1.98892 × 1030 kg), we get an evaporation time of 2.098 × 10^67 years—much longer than the current age of the universe at 13.73 ± 0.12 x 10^9 years.

Is that sort of thing a minor matter, compared to the false prophesies and inane, hateful bullshit found in your holy book? (This is a rhetorical question. Of course it isn’t.)

33. consciousness razor says

sorry, a solar mass is 1.98892 × 10^30 kg, according to wiki.

FTB won’t let me write superscripts, and I missed that one.

34. Alex says

Hm, why is misspelling of names such an unreasonably reliable indicator of cluelessness? Hawkings, Hawkins, Dawkings, Meyers, Einstien, Justin Beiber…. I could go on….

35. Alex says

Yet can he say science can dismiss a need for a creator in matters of the universe when science(whatever that is) has not cured medical problems like his.
What’s more intellectually difficult?

Well, actually…
As a physicist, I can tell you, curing cancer is a much more complex and messy problem than cosmology. So, yes, he can.

36. Marlin says

Is there going to be a place on the internet where I can see this? What is the program actually called? I can probably find it. I don’t have a television service – I absolutely refuse to pay to watch commercials.

37. some Matt or other says

Alex,

I think without having read the post in detail, we can dismiss the claim about “literal nothingness” out of hand. If they calculate tunneling amplitudes, they do start with a quantum mechanical state, maybe something like a vacuum state. That is most definitely not “nothingness”, much less “literal nothingness” ;)

Actually I missed the fact that the same post is in this thread too, right here. Also, Guth and Vilenkin, researchers quoted in that post, can be seen talking about their ex nihilo theories in this part of a video PZ just posted.

I don’t have the background to even begin to evaluate their statements, but my point isn’t that they’re necessarily true, just that they’re out there in the mainstream at all. They give me a better sense of what Hawking is probably talking about in his brief pronouncements.

stvs,

It means that cause doesn’t even make sense in the physical description of radioactive decay, which is presented by this Feynman diagram. Particles may take any continuous path through space-time—curved, loopy, even faster than light speed!—therefore, it doesn’t make sense to ask what “caused” the W boson any more than it makes sense to ask what “caused” the photon in electron repulsion.

Thank you for the links and explanations, but I’m afraid I don’t follow. I understand the notion that subatomic particle behavior is basically a gigantic game played with weighted dice, but using that idea to then say that radioactive decay has no “cause” makes me wonder what the word “cause” means in this context. Like I said above, my understanding is that decay is caused by an imbalance of forces inside the nucleus, which results in an unstable structure that’s prone to ejecting bits of itself in the form of errant particles. Of course I’m using gross Newtonian terminology, and if I understand you correctly, you’re saying that this subatomic “motion” is solely a function of probability of location, not the result of classical forces like propulsion and inertia. And the inherent randomness in those probabilities is “causeless.” I’m fine with that as far as it goes, but those probabilities can clearly be constrained – as a balanced collection of protons and neutrons will do to each other – so there most be something we can call cause-and-effect happening there, even if it’s not precise down to the individual particle. As I see it, calling the whole phenomenon “causeless” leads to the reductio ad absurdum that Hume’s Ghost presented. The demon of causelessness is released by accepting the existence of true randomness, but it seems to me that probability also implies cause-and-effect; otherwise the randomness of the universe would be so random that no order, regardless of its fuzziness, would be possible.

But another way of looking at this occurs to me: Would it be appropriate to say that atomic stability is actually the “caused” state, while instability is “uncaused” in that it’s what happens when randomness is given an outlet? For instance, in a room full of bouncing balls, the walls cause the balls to stay within a certain space, but you open a door and a ball flies out. Did the open door “cause” the errant ball? Not really; the open door was the absence of a cause for the ball to stay in the room; the true cause of the ball being outside the room is whatever put the ball in motion in the first place. Extending the metaphor to a radioactive atom, since the motion of particles is all about probable locations instead of the classical forces, there isn’t much of a “cause” left to assign to the emission of a particle. The imbalance of forces can explain why there was a metaphorical open door, but why anything would “fly out” is more about randomness than cause-and-effect. Is that somewhere near what you’re getting at?