If you folks would be so kind as to permit me a digression related to the OP. When I first saw the video I was pretty much blown away, not just because of the definitive matter of fact way that Carroll laid out a proof that there was no such thing as any possible notion of an afterlife in any sense, but the entire description of the LHC findings, and the meaning and significance of the Higgs field/particle along with the fact that modern physics relies on a theory, that I had never heard of, QFT. As Carroll states, physicists don’t do a great job talking about fields apparently.
I liked to believe that I follow developments in Science, at an average level if not above average, especially as it relates to astronomy and cosmology, I've seen all the PBS documentaries on String Theory, read various pop-sci books by Hawking, Brian Greene and others, I was really shocked that I actually knew so little about the subject that I struggled to find a reason to understand it.
I decided in order to evaluate the overall video, as well as a personal desire to "get to the bottom" of what physicists apparently actually believe, not what the science median tells us, I needed to get up to speed on current particle physics. To be honest I was also partially motivated to try to better understand some of Sean Carroll's specific claims of other forces and particles being ruled out. I was a bit
skeptical, even though I am pretty much an atheist, but I find it what Carroll said remarkable and I don't really hear the same kind of definitive, certainty coming from other physicists at all. So either other physicists agree and for some reason generally don’t get their hands dirty with these topics, or Carroll may have an outsider viewpoint or hubris? which to be honest, I haven’t really seen much evidence either way in this thread, on how mainstream his interpretation of these facts really are.
For my own edification I’ve read several books in the past month, these all just happened to be in my local public library (yes they still exist).
Quantum: A Guide for the Perplexed by Jim Al-Khalili (2003, U. of Surrey
), an overview of history of development of Quantum Mechanics and some quantum topics, from superpositions, non-locality, entanglement, practical applications etc. I found it a great read, especially how the Many Worlds
interpretation is just that, one of many interpretations, not a fact, as seems to be claimed by every pop-science documentary I’ve seen on TV. Next up:
The Elusive Neutrino: A Subatomic Detective Story by Nickolas Solomey (1997, Wichita State U.), a wonderful overview not simply of the story of the neutrino, but pretty much all particle physics of the 20th century, with plenty of graphical depictions of experiments and apparatus for neutrino detectors, particle accelerators and colliders and their detection experiments. the LHC was a far-away dream in that book, so I realize there have been plenty of science since it was published which was the only downside. Last but not least,
Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law by Peter Woit (2006, Columbia), which despite it’s name also gives a rather deep account of the mathematics of the development of the standard model, as well as the reasons that physicists have problems with the current standard model and are inspired to look for other alternatives, string theory being the most prominent and in Woit’s opinion, most misguided. The math in this book was almost too much for me to absorb, but it began to scratch the surface of QFT being vectors in Hilbert spaces with complex numbers, the intricacies of the sets for the standard model: SU(3)XSU(2)XU(1), oh and the symmetry, my god he cares so much about symmetry. If you don't like String theory, this might be the book for you. Even after these three books, I still have so many questions, but I found all to help with different parts of the puzzle, I would recommend either Quantum, or the Elusive Neutrino, But Don’t Take My Word For It.
Back to Sean Carroll talk. So in the video, I believe Carroll makes several specific claims (I’ve watched it 3-4 times now).
At around 33:30 with the Higgs Boston we now have a complete theory(The Standard Model) that explains 100% of the “everyday world”, and “The laws of physics underlying everyday life are completely understood”, he goes on to assert that “we know that there are no new particles or forces that can be relevant to everyday life”.
At about 38:20 he discusses about constraints on new particles, e.g. “Zilbot” particle. If you are proposing a new particle interacts with the brain then what you mean is: Feynman diagrams with the “Zilbot” and a new interaction. He then states it’s a rule that you can rotate particles 90 degrees, to show “If a new particle can interact with ordinary particles…then the particle can be created in high-energy collisions”. And therefore we have not made any in a particle accelerator. (I asked about this in my post on
page 9 of the thread). He continues from 40:00 if new particles could hide from our experiments if they were very weakly interacting, too heavy to create or too short-lived to detect.
At 41:46, he describes experimental constraints on new forces (presumably by particle experiments? Would be nice to have more information on that slide actually, and what exactly it refers to.
I have to say, my reading on the subject has not really answered my initial questions.
Regarding point #1, I think the crux of the argument rests on what is known about everyday life, and how you would define that scope. There are aspects of physics which we all agree the standard model does not cover, such as what has been pointed out already in this thread, with Dark Matter. Some theories of dark matter as well as supersymmetry include stable particles i.e. WIMPs which would conceivably be passing through us that we have not detected. Is it impossible that there could be some weak influence that on aggregate or in unique cases produces a macro consequence? Or if not WIMPs then we really don’t know what the physics are for whatever is that missing mass-energy which we can see only gravitational effects of. To me there is too much uncertainty to really rule out anything. Not to mention, on the Quantum side of things, I do believe there is still a debate about how to actually interpret what the equations are telling us for example with decoherence, or the measurement problem.
Point #2 - I still haven’t found any other specific source on that notion which would require that to always be true, maybe it’s a point too fundamental to bother mentioning in other contexts. But even so, often what we are measuring in detectors of these experiments are the charged particles often from the decay of more massive and short-lived particles that we can actually detect, hence we don’t actually “see” neutral charged neutrinos or Z bosons although they are there and being produced (
another source on this). I would question what we would really detect if there some neutral charged particles that interacted with normal matter with this hypothetical new force? Another counter example of the picture to me is gravitons. We know gravitons can not be very massive (don’t they have to be massless like photons?), they interact through the gravitational force with everyday matter yet are not produced in our collision experiments or if they are, we aren’t seeing them?
Point #3 - I still would like to know more about how weak and on what distance scales are ruled out, again I was not sure what they diagram was referring to being ruled out from experiment, or which experiments.
One last point would be that although the talk did a pretty convincing job of ruling out new forces or particles that would interact with everyday matter, what about if some forms of Woo are just complex interactions with the known forces.
For instance, don’t the proponents of ghost hunting
explicitly invoke electro-magnetic phenomena related to ghosts which they purport to detect with their visible light or IR cameras, “EMF detectors” and other electronic devices? Some sort of weird electromagnetic phenomena wouldn’t be ruled out by this logic per se.
Thanks to the OP for this video and this thread, I've enjoyed being this into the weeds in Science, and it's gotten me a much better understanding of the challenges of physics and what recent discoveries actually mean to some extent. Anyone else have suggested reading on QFT in particular?
