WLC Reacts! to Neil deGrasse Tyson on Dark Energy
Dr. William Lane Craig watches and responds to a video of astrophysicist Neil deGrasse Tyson on the existential crises of dark energy in the universe.
DR. DEGRASSE TYSON: I lose sleep over this fact. . . . I don't want to be blamed if you cannot get to sleep tonight.
STEPHEN COLBERT: I'll be okay.
DR. DEGRASSE TYSON: OK. Alright. So this dark energy in the future will render the universe so large, having accelerated so significantly, that all the galaxies of the night sky will have accelerated beyond our horizon. And all the galaxies are the source of our knowledge of cosmology, of the Big Bang, everything we know about the history of the universe comes to us from these galaxies. If they accelerate beyond our horizon, the next generation of cosmic explorers will only have the stars of the Milky Way to think about. There would have been an entire chapter of the universe ripped from their view, and they will be trying to contemplate an understanding of the universe without a significant part of what its past was. And so I lose sleep wondering, today, was there some previous chapter ripped from the universe itself and here we are, and here we are . . . you know, touching the elephant, not knowing that in fact there's an elephant standing there. Or maybe there's a shadow of the elephant and the elephant has been moved. We don't know what we don't know.
DR. CRAIG: DeGrasse Tyson is always an engaging personality; even if you disagree with him, he has important things to say. And the situation he's describing here is that due to the accelerating expansion of the universe, our galaxy will become increasingly marooned, in comparison with the other galaxies, until finally we are left entirely alone with no contact with anything outside us. And he has two worries about this. His first worry is that this really is bad news for the future of cosmology. You're not going to be able to study the large-scale cosmos if you're marooned on a tiny little island in the midst of this expanding universe. So it's bad news for cosmologists. Now of course unless humanity through some catastrophe reverts to the Planet of the Apes, we should always have our past knowledge of that wider, larger universe out there in our libraries and records. So hopefully that science and that knowledge will be preserved and not lost to those future cosmologists if they live that long. Now the second worry that deGrasse Tyson expresses is what if we're already living in such a situation and we don't know about this other wider reality? Well, as a matter of fact in a sense, that's already happened. That's exactly what the James Webb Telescope has revealed – that the universe is vastly larger than we thought, that what we observe is a relatively small patch of the universe, and that for the first time James Webb has enabled us to peer into deep space and realize how vast the universe truly is, something of which we were not previously aware. But given the evidence for the expansion of the universe and the impossibility of oscillating models of the universe, I don't think we need to lose sleep over the idea that there might have been another wider reality prior to our own. Even on multiverse scenarios these cannot be extended infinitely to the past, and so I think in the absence of some good evidence for such a hypothesis we don't need to worry about it. In a sense these skeptical worries are like classical philosophical arguments that you might be a brain in a vat wired up with electrodes by a mad scientist being stimulated to believe that there's an external world and other minds about you. In the absence of any sort of good reason to believe such a skeptical hypothesis I don't think you need to lose sleep about it.