Penrose and Craig on Conformal Cyclic Cosmology

From Dr. Craig himself…

What do you make of it?


I listened to this and found Roger Penrose to be very clear and William Lane Craig to be totally incoherent.

WLC said he is a Lorenzian regarding time. Penrose asked what’s a Lorenzian? Craig had no idea what he meant by saying that he was a Lorentian. Craig is clearly not a mathematical physicist or any kind of scientist. Craig doesn’t even understand that a photon doesn’t experience time. Craig has a layman’s understanding of cosmology, quantum mechanics, GR, neuroscience, conscienceless. Perhaps enough to get a B in a university physics course. Putting Craig and Penrose in the same room makes no sense. Penrose is a physicist, Craig is a metaphysicist, whatever that is. If WLC is the best theologian in Christianity today, Christian Theology is in trouble.

Why do you think he is moving to be a curious theologians? Wait a moment! That wasn’t Penrose who said this, was it? Now I am a bit confused.

@MStrauss and @david.heddle what are your thoughts on this?

I’m not a big fan of Craig but that isn’t true.


What exactly do you want our thoughts on? There are a lot of threads I see here.

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Did Penrose say this or is that just a quote from the middle link that was said by Dean Mayes who it says is an intensive care nurse from Australia?


Title needs to be changed. I misunderstood. Penrose did not say this. Will change it in a moment. That was my honest mistake.

What can teach us about this:

The discussion moves on to Penrose’s Conformal Cyclic Cosmology (CCC), which aims to remove the singular beginning of our universe and solve the problem of its seemingly special “low-entropy” beginning.

So does Penrose’s CCC model remove the needs for a beginning? The theory predicts that our universe is one ‘cycle’ in a sequence of universes that emerge over vast ‘eons’ of time as the energy runs out in each cycle. Penrose claims that, as well as solving these problems, there is empirical evidence of a remnant from a previous cycle.

Firstly, the model first appeared in a 4-page conference proceedings in 2006 and in a popular-ish level book in 2010, but didn’t appear in a peer-reviewed paper until 2018. For non-scientists, this is a bit like hearing that a movie has not been screened for critics before release.

The papers contain rather few equations, and require a hefty amount of new particle physics to accompany the new cosmology. His 2012 conference paper finishes with the comment, “Clearly CCC raises many issues here which need detailed checking for their internal consistency.”

Secondly, the claimed observational support for the model is entirely unconvincing. Penrose mentions the most recent claims (“99.4% and all that”), but there have now been three cases in which “claimed evidence for the CCC turns out to be nothing.”

In 2010, a paper claimed to find CCC-consistent ring patterns in the cosmic microwave background, but these were refuted by three independent studies in 2011. In 2013, CCC advocates claimed to find sets of concentric rings, only to be debunked again.

Finally, in this interview, Penrose discusses the 2018 claim that there are rings with a large temperature gradient across their width. Despite the talk of a greater than 99% probability, Dylan Jow and Douglas Scott in September 2019 (after this dialogue, which was originally recorded in May) showed that the analysis must account for the fact that the CCC doesn’t predict a specific scale for the size of the rings. Once this is done, the features identified by CCC advocates can be found in at least 13% of random simulations of the sky, that is, simulations where we know by construction that no such ring is actually present.

Despite Penrose’s evident brilliance and commitment to the theory, CCC remains an unproven and highly speculative hypothesis.

I don’t know about CCC. Teach us?

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Would that more atheists were as pensive and thoughtful as Penrose.

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I liked the rebuttal to the fine-tuning “self-selection effect” argument in the third one.

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For those interested, here’s Craig’s take on how the interview went:

And here is another podcast where he discusses Penrose’s CCC:

I would be curious to hear from any of the @physicists in the know whether Craig’s criticism of CCC is correct or not.

ok, Craig has an understanding of the latest results of cosmology without formal training or work in this area. But putting him next to a Penrose, a Sean Carroll, a Lawrence Krause, or a Tyson is like putting a guy who played some baseball in High School with MVP major leaguers. Sure Craig is up on the latest results but his not a mover nor a shaker in the public understanding of cosmology.

I don’t know a lot about CCC, but I did talk about it in a recent podcast I did recently at Texas A&M with their Ratio Christi club. I should look into it more and write a blog post about it. The podcast can be found at at about the 12:15 mark.


Craig is an MVP major leaguer in philosophy, who can scrimmage with the physicist, partly because he is smart enough to pass the ball when needed.

Dialogues like this are significant. Craig knows a lot about physics, even though he is not a physicist. Penrose knows a lot about philosophy, even though he is not a philosopher. This is the grand conversation, as the least in part.


I enjoyed listening to Penrose, but Craig was all mishmash. If Craig is an MVP major leaguer in Philosophy, Stephen Hawkings is correct that science has now taken over Philosophy. W.L. Craig is no Daniel Dennett who is today’s MVP in science based Philosophy.

Craig has to do better than just saying that “Theism is a better argument than Atheism for what happened at the beginning of the Universe”

Science is studying the origin of the universe and had made significant progress using physics, mathematics, computers, and satellites. Neither Theism nor Atheism has anything to do with the scientific study of cosmology. As you know, science is neutral on Theism and Atheism.

I’m definitely agreeing with @Patrick here. The CCC model is interesting but its rejection or failure is not actually positive evidence for theism. There are some valid critiques of the model and it had to deal with some really challenging obstacles (i.e. see this article with a slightly misleading title: Quanta Magazine). I think some of the critiques in the first link are spot on, but the problem I have is that the subtle implication that the falsification of CCC strengthens the theistic argument. It does nothing of the sort as a lack of scientific explanation is not evidence for anything. It really annoys me to take the apparent beginning of our universe and then capitalize off of such a lack of explanation as evidence for God. It’s not evidence for God in the same sense that having a scientific explanation is not evidence against God as @Patrick pointed out.


Craig Embarrassed him.


The main idea of the Conformal Cylic Cosmology (CCC) is this: The far future of the Universe in our current model is very similar to its very far past, the only difference being that the Universe in the far future is much larger than the far past Universe. A (part of) conformal transformation is a change of scale, so under a conformal transformation, the far future of the Universe is identical to the far past of the Universe. What if this conformally transformed far future of the Universe is the far past of the next Universe? This is the CCC hypothesis.

The evidence for CCC is very weak; Penrose claimed to see a signal at 6 sigma in the CMB map, but multiple groups have refuted this claim. At this point, the CCC is considered a fringe model by most cosmologist.


What signal is CCC supposed to produce and why? That’s the part I’m hazy on.

I’ll answer later - have to board a plane.