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Have We Reached the End of Physics?

March 13, 2016     Time: 18:42
Have We Reached the End of Physics?


Dr. Craig discusses yet another example of how amazingly fine tuned the universe is!

Transcript Have We Reached the End of Physics?


KEVIN HARRIS: Dr. Craig, we are going to get into some interesting science here. This was a TED talk by a particle physicist Harry Cliff, “Have we reached the end of physics?”[1] Just that title alone flies against what scientists say that there is always a new discovery to be made. To say that we are at the end of it here is pretty controversial. In fact, this article[2] which was from the end of 2015,

A deeply disturbing and controversial line of thinking has emerged within the physics community.

It's the idea that we are reaching the absolute limit of what we can understand about the world around us through science.

DR. CRAIG: What they are talking about here is not that we’ve discovered everything, for example, about the oceans on the Earth or the human brain, that there isn’t much, much more for science to discover. It is talking about high level physics – that we may not be able to push our current models of physics much further than what they are today. That is the fear.


"The next few years may tell us whether we'll be able to continue to increase our understanding of nature or whether maybe, for the first time in the history of science, we could be facing questions that we cannot answer," Harry Cliff, a particle physicist at the European Organization for Nuclear Research — better known as CERN — said during a recent TED talk in Geneva, Switzerland.

Equally frightening is the reason for this approaching limit, which Cliff says is because "the laws of physics forbid it."

This got my attention so far! He says,

At the core of Cliff's argument are what he calls the two most dangerous numbers in the universe. These numbers are responsible for all the matter, structure, and life that we witness across the cosmos.

And if these two numbers were even slightly different, says Cliff, the universe would be an empty, lifeless place.

Does this remind you of anything?

DR. CRAIG: It certainly does! This sounds like the fine-tuning of the universe. He is claiming here to identify two numbers – two physical quantities – which, if different, would make the universe life-prohibiting. He will explain exactly how these exact values of these physical constants or quantities must be what they are in order for the universe to be life-permitting.

KEVIN HARRIS: While this is a very highly technical subject, maybe our listeners can look further into this. It is fascinating. We are going to summarize here.

The first dangerous number on Cliff's list is a value that represents the strength of what physicists call the Higgs field, an invisible energy field not entirely unlike other magnetic fields that permeates the cosmos.

As particles swim through the Higgs field, they gain mass to eventually become the protons, neutrons, and electrons comprising all of the atoms that make up you, me, and everything we see around us.

Without it, we wouldn't be here.

We know with near certainty that the Higgs field exists because of a groundbreaking discovery in 2012, when CERN physicists detected a new elementary particle called the Higgs boson. According to theory, you can't have a Higgs boson without a Higgs field.

DR. CRAIG: OK. So the idea here is that this elementary particle called the Higgs boson (after Peter Higgs) that was discovered in 2012 is responsible for a field which gives the masses to all of the other elementary particles in the universe like protons and electrons – things of which physical substances including ourselves are made. This Higgs field and the Higgs boson is essential for the existence of the physical universe that we see.


But there's something mysterious about the Higgs field that continues to perturb physicists like Cliff.

According to Einstein's theory of general relativity and the theory of quantum mechanics — the two theories in physics that drive our understanding of the cosmos on incredibly large and extremely small scales — the Higgs field should be performing one of two tasks, says Cliff.

Either it should be turned off, meaning it would have a strength value of zero and wouldn't be working to give particles mass, or it should be turned on, and, as the theory goes, this "on value" is "absolutely enormous," Cliff says. But neither of those two scenarios are what physicists observe.[3]

"In reality, the Higgs field is just slightly on," says Cliff. "It's not zero, but it's ten-thousand-trillion times weaker than it's fully on value — a bit like a light switch that got stuck just before the 'off' position. And this value is crucial. If it were a tiny bit different, then there would be no physical structure in the universe."

DR. CRAIG: Exactly. So this Higgs field is just one more example of the fine-tuning of the universe for embodied conscious life. It needs to be tuned to an exquisitely precise value in order for the universe to be life-permitting.

KEVIN HARRIS: CERN is still working on this. They are still looking at,

detecting brand-new particles at the newly upgraded particle accelerator at CERN. So far, though, they're still hunting.

Dangerous No. 2: The strength of dark energy

Cliff's second dangerous number doubles as what physicists have called "the worst theoretical prediction in the history of physics."

This perilous number deals in the depths of deep space and a mind-meltingly complex phenomenon called dark energy.

Why do you think he calls it “the worst theoretical prediction?”

DR. CRAIG: Because it is so far off. This is the cosmological constant problem. The cosmological constant drives the acceleration of the universe. It has a value, as we’ll see in a moment, that is so finely tuned that it is just incomprehensible. If it were what it was predicted to be, the universe would again be life-prohibiting. It is one of the most dramatic examples of fine-tuning.


Dark energy, a repulsive force that's responsible for the accelerating expansion of our universe, was first measured in 1998.

Still, "we don't know what dark energy is," Cliff admits. "But the best idea is that it's the energy of empty space itself — the energy of the vacuum."

If this is true, you should be able to sum up all the energy of empty space to get a value representing the strength of dark energy. And although theoretical physicists have done so, there's one gigantic problem with their answer:

"Dark energy should be 10120 times stronger than the value we observe from astronomy," Cliff said. "This is a number so mind-bogglingly huge that it's impossible to get your head around . . . this number is bigger than any number in astronomy — it's a thousand-trillion-trillion-trillion times bigger than the number of atoms in the universe. That's a pretty bad prediction."

On the bright side, we're lucky that dark energy is smaller than theorists predict. If it followed our theoretical models, then the repulsive force of dark energy would be so huge that it would literally rip our universe apart. The fundamental forces that bind atoms together would be powerless against it and nothing could ever form — galaxies, stars, planets, and life as we know it would not exist.

DR. CRAIG: Here we have a second example of this remarkable fine-tuning. The cosmological constant that drives the acceleration of the universe is also incomprehensibly fine-tuned to permit the existence of embodied conscious life in the universe. So we have two examples here of fine-tuning among many, many more examples that could be mentioned.

This, of course, then cries out for some explanation. Is this due to some sort of physical necessity that would explain it? That seems highly implausible. The best theories of contemporary physics suggest that these fundamental constants and quantities are not fixed by what we know of the nature of the physical world – by physics. So the question is: could they be due to chance alone? This alternative seems highly implausible in light of the astro . . . well, I was going to say astronomical improbability, but, as Cliff says, to call it astronomical would be a wild understatement. It is incomprehensibly improbable that these constants and quantities should fall by chance alone into the almost infinitesimal life-permitting range of values.[4]That suggests that perhaps the best explanation is the third one which is design – the reason the universe is fine-tuned for the existence of embodied conscious observers is because it was designed to be that way by a transcendent cosmic intelligence.

KEVIN HARRIS: He concludes the article by saying,

Getting answers could be impossible

Cliff said there is one possible way to get some answers, but we might never have the ability to prove it.

If we could somehow confirm that our universe is just one in a vast multiverse of billions of other universes, then "suddenly we can understand the weirdly fine-tuned values of these two dangerous numbers [because] in most of the multiverse dark energy is so strong that the universe gets torn apart, or the Higgs field is so weak that no atoms can form," Cliff said.

DR. CRAIG: OK, here he actually uses the expression “fine-tuned” values. What does he opt for as one possible way to get answers? The multiverse scenario, which is essentially an appeal to chance. It is to say that if you have an infinite number of randomly ordered universes then by chance alone these finely tuned universes will appear in this world ensemble or in this multiverse, and only finely tuned universes have observers in them. So we shouldn’t be surprised to be observing our finely tuned universe. That is the only kind of universe that we could observe.

Notice that he doesn’t even consider the hypothesis of design as a possible explanation. For him, the multiverse is a kind of God-surrogate that will explain the fine-tuning by appeal to chance alone. But here people like George Ellis have emphasized that the multiverse proposal may never be testable. There would be no way to confirm the existence of an infinite number of other universes. How could you ever know that they were infinite in number rather than finite?

KEVIN HARRIS: Or even if there were three or four. You’d have to – what? - go to the end of this one and then go over there and look at the next one?

DR. CRAIG: Obviously you couldn’t do that, so you would have to have some sort of an indication within our universe that whatever formed our universe would likely form other ones as well. Even if you were able to show that there were other universes, that wouldn’t mean that they were infinite in number nor would it mean that they randomly vary in their fundamental constants and quantities so that every combination gets tried out rather than repeating, say, a monotonous pattern. So the hypothesis is really a metaphysical hypothesis no better than appealing to divine design.

In fact, as I’ve shared in my published work, there is a really big problem with the multiverse hypothesis as an explanation of fine-tuning that Roger Penrose has pressed very forcefully, and that is it is not true that observers can exist only in finely tuned universes. If you have an observer who just fluctuates into existence out of the quantum vacuum and then disappears, you could have a single brain (these are called Boltzmann Brains) that just fluctuates into existence, observes its otherwise empty world (maybe as an illusion of an external universe around it), and then disappears. That kind of universe would be vastly, vastly more probable than finely tuned universes such as the one that we observe. So on this multiverse hypothesis we ought to believe that we are Boltzmann Brains and that nothing else exists. You don’t exist. The world doesn’t exist. My own body doesn’t exist. It is all an illusion of my consciousness. And no sane person thinks he is a Boltzmann Brain. Penrose says that these multiverse hypotheses are really worthless as explanations of this fine-tuning of the universe.


To prove this, physicists need to discover new particles that would uphold radical theories like string theory, which predicts the existence of a multiverse.

I have to say, even after having read on string theory, I didn’t know that string theory predicts a multiverse.[[5]

DR. CRAIG: It doesn’t by itself. This is misleading. Super-string theory, or M-Theory, says that there is a so-called cosmic landscape of possible universes that vary in their constants and quantities that are consistent with the laws of nature. There are about 10500 universes like this. But those universes don’t actually exist. This is just a list of possibilities is all. You have to then marry super-string theory with some kind of inflationary theory of the origin of the universe to generate these many worlds. This is just complete conjecture. Indeed, string theory hasn’t paid dividends on the amount of effort that has been expended on it. It hasn’t been fruitful in the way theorists had hoped. My understanding from physicists is that it is actually incompatible with these inflationary theories of the origin of the universe. In any case, even if you get a multiverse, that isn’t going to guarantee that you have an infinite number of randomly ordered universes. So the multiverse theory, I think, remains a speculative metaphysical hypothesis.

What is significant that is alluded to in the title of Cliff’s article (“Have we reached the end of physics,” which oddly enough he doesn’t discuss really in this article) is that we may never be able to get answers to these questions. Because, as George Ellis (the world’s most famous cosmologist) explains, it would require energies be reached in these colliders that are beyond anything we could ever build. He says these colliders would have to be as big as the surface of the Earth in order to attain the sorts of energies that would be necessary in order to test these theories. So, in fact, the prospects that the naturalist longs for that someday science will discover a theory that would explain the fine-tuning of the universe may well be nothing but a pipe dream.

Physics in the past has declared that it has come to an end before. At the end of the 19th century similar predictions were made that physics had come to the end. But Ellis points out that there they felt that they had simply arrived at a complete picture of the world. The situation today is very different. It is not that physics thinks it has arrived at a complete picture of the world. It is rather we have reached the limits of our experimental capacity both in terms of the energies that we can attain in these colliders (we just can’t build them big enough) and in terms of what we can see in distant space. We can’t see any further back toward the Big Bang in space. As Cliff says, it is the laws of physics themselves which may have mandated that we have reached the end of physics.[6]