Have We Disproven the Big Bang? | David Kipping

One of the things I wanted to ask you, for example, is that I know there's— I know this isn't your area of specialty, but any light you could shed on it would be, uh, um, appreciated. I've heard that the new telescopes, which can see farther into space than anything we've managed before and farther back into time, therefore have put some wobbles in the, what was almost universal acceptance of the theory of the big bang.

So, can you clue us in a little bit about at least what's going on in astrophysics with regards to that sure debate?

So, we have this telescope that was launched two years ago, the James Webb Space Telescope. It is the most powerful instrument we have right now for peering back into the far reaches of the universe, and thus, therefore, into the past. Because of course, something that’s very far away from us takes a long time for that light to travel.

So essentially, the light we are seeing from some of these objects is over 13 billion years old, and thus we are seeing the universe in its first few hundred million years. When we look at the universe at this very ancient primordial phase, we are surprised to see rich structures, like fairly mature looking galaxies. They're still nothing as mature as what we have like the Milky Way, but surprisingly mature given the epoch we are looking at in our data.

Similarly, for large black holes as well, we’re seeing black holes more massive than we would expect in the center of some of those galaxies. So the puzzle has been: how do you build this stuff fast enough?

Obviously, you could argue that maybe you need to totally rip up the textbook and say, you know, all of our cosmological models are wrong, including the Big Bang; we need to change everything. I don't think most astronomers are quite ready to rip up the textbook. I think there are other ways to explain what we are seeing without going quite so drastically.

Speaking with my colleagues about this, we had a wonderful colloquium, and I was speaking to some of my colleagues about making sense of this. One of the interesting things I took away from that was the models of star formation that we apply are calibrated to the local universe, and they may not be actually applicable to this earliest epoch.

So when we see these ancient galaxies, we are basically saying there are too many stars, too many built stars, and too much stuff, faster than it should have done, based off the rates at which we think stars can form. But really, the rates at which we think stars can form is calibrated to what we see around us now, which is not necessarily representative of the conditions—well, certainly cannot be representative of the conditions of the early universe.

In fact, when they've gone back and revised those models and updated them to account for the much stronger star formation and more intense densities that they naturally have in these early epochs, it actually does predict these galaxies. In fact, we could have predicted many of these galaxies had we just been maybe a little bit more thoughtful about what we put into the physics of those models in the first place.

But it did make, of course, a spectacular headline to claim that the Big Bang model was wrong. I don't want to totally dismiss it, but there are still challenges. I don't think it's quite as dramatic as has been portrayed.

I see. I see. So part of the problem there too was the extension of that principle of homogeneity or uniformity in the temporal domain when it wasn't appropriate. As you said, if the conditions—well, the conditions are obviously different soon after the big bang, clearly.

So then the question would be: well, how consequential are those differences? Your argument is that the magnitude of those differences was conservatively underestimated, and that's cast some of the theory into disrepute. But that doesn't mean that, at least in your estimation, that the baby has to be thrown out with the bath.

Yeah, I think if you throw out all of, you know, the Big Bang model—which really, when we say the Big Bang model, we don't really just mean the Big Bang. What we call is Lambda CDM, which means Lambda is dark energy, CDM stands for cold dark matter. You can think of Lambda CDM as essentially the standard model of astronomy, in the same way there is a standard model of particle physics that includes the basic fundamental particles.

We have a standard model of astronomy and cosmology, and so this model has been extraordinarily successful, as indeed has the standard model in particle physics. It explains such a wide span of observations that were you to throw it out, it would be extremely difficult to understand how it could coincidentally explain such a vast array of diverse phenomena so exquisitely.

So, I think we're not, you know, astronomers do like it, physicists like it when we get to rip things up, but given the extraordinary success of the model and this, you know, one interesting puzzle, I don't think we're quite ready to throw in the towel at the first punch.

You know, we're willing to fight back a little bit. I think it was A.R., I think it was Arthur C. Clarke, possibly—I might be wrong about this—who, no, it was Carl Sagan who said that extraordinary claims require extraordinary evidence.

And so, well, the proper response to that is that you always modify your theory no more dramatically than is minimally necessary, right? That's just the—otherwise, that's true even psychologically. You know, if you don't, every time you're upset with your wife, you don't think that now divorce is in the offing, right? That's just not the solution to the problem.