[lulmerchant]

An argument between ‘basic’ and ‘fundamental’ is a semantic one, and bordering on pointless.

QED works quite well in most cases, but only if you don’t look too closely, and only if you ignore one of the fundamental forces. QED offers no explaination for gravity, which even non-physicists know exists.

What is gravity? What is a particle? What is space? These are all quite basic questions that were not even close to having complete answers for. QED provides a “good enough” explaination for how particles and space work, just as relativity gives a “good enough” explaination of gravity. But any physicist who’s being intellectually honest knows that we only have a rudimentary understanding of these concepts. The wave function is just an excellent tool we use to smooth out our lack of understanding. Your comment is a perfect example of the arrogance that pervades the scientific community, and the inability to acknowledge the limits of our own understanding. Which I think only inhibits the wider community’s ability to communicate effectively with the general public.

[raattgift]

> QED offers no explanation for gravity

It does; gravitation in perturbative QED on time-dependent curved backgrounds has exactly the same explanation as General Relativity. [1] This generalizes very well. [2]

One can look at it the other direction too: General Relativity guarantees flat spacetime in the neighbourhood of every point on the manifold with signature 1,3 or 3,1. As long as the radius of curvature is large compared to the system under study there is no trouble at all (QED systems are usually pretty tiny, so you're good down to and through astrophysical black hole apparent horizons). This is implicit in laboratory tests of QED.

> But any physicist who’s being intellectually honest knows that we only have a rudimentary understanding of these concepts

Everyone should be honest about how much she or he really knows, and how much he or she can judge how much someone else really knows.

"The first principle is that you must not fool yourself — and you are the easiest person to fool" -- Feynman

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[1] [BirrellDavies] N.D. Birrell and P.C.W. Davies, Quantum fields in curved space, Cambridge University Press, Cambridge U.K. (1982).

[2] [BGZV] A.O. Barvinsky, Yu.V. Gusev, V.V. Zhytnikov, and G.A. Vilkovisky, SPIRES-HEP:Print-93-0274(Manitoba), (1993). https://arxiv.org/abs/0911.1168

[dbasedweeb]

Basic = simple

Fundamental = bedrock

QED works to the best ability of any test, down to one part in ten billion, so looking very close indeed. Then in order...

What is gravity? The geometry of spacetime.

What is a particle? A localized excitation of a field.

It may be that you don’t like or understand the answers, but they exist and allow people to make precise predictions, build machines that work based on said principles. Maybe you’re confusing scientific answers with philosophical ones?

[lulmerchant]

Basic

Adjective

1. forming an essential foundation or starting point; fundamental.

Your answers to those questions are either deliberately over-simplifying to avoid the question, or you don’t understand QED yourself. Your definition of a particle describes a possible outcome of a measurement, and ignores the existence of a wave function. Your description of gravity cannot be created in QED. You have provided no explanation of space whatsoever, which is so woefully unexplained by quantum mechanics, that it is referred to as the ‘vacuum catastrophe’.

Anybody who investigates these concepts can see that our understanding of them is woefully incomplete. However scientists tend to have a very hard time acknowledging these limits of our understanding, and will often respond to such acknowledgements with thinly veiled contempt. Just as you have done by trying to undermine my opinion on them, rather than responding to what I have said. I think that by failing to acknowledge the limits of scientific understanding, maybe you are confusing science with religion?

[davidcuddeback]

> scientists tend to have a very hard time acknowledging these limits of our understanding

That couldn't be further from the truth. Scientists have been very upfront about the limits of our understanding, particularly when it comes to combining gravity with quantum physics. Listen to Neil DeGrasse Tyson or any other science communicator talk about general relativity or quantum physics and you'll hear them drive this point home.

We know that quantum physics and general relativity don't combine well, yet both are among the most thoroughly tested theories in science. We know we need new physics to combine them, but they're still useful in their own domains. Just like before we had general relativity, we knew that Newtonian gravity was incomplete because it didn't correctly explain the orbit of Mercury. But Newtonian gravity was (and is) still useful, even with those limitations. The key is knowing where the limitations apply.

General relativity applies to scenarios of high mass/energy. Quantum physics applies at small scales. They both work great in their respective domains. It's when you have high mass/energy in a small volume that things break down, because both quantum physics and general relativity apply, but we don't know how to combine them.

> I think that by failing to acknowledge the limits of scientific understanding, maybe you are confusing science with religion?

I don't see dbasedweeb failing to acknowledge anything. dbasedweeb wrote, "incomplete in very extreme conditions such as the interiors of black holes or the first instants after the Big Bang," which happen to be two places where quantum physics and general relativity are both applicable and we therefor run into the limitations that I mentioned above.

[lulmerchant]

The theories are incompatible at all energy levels, it's simply that those are two examples where we can't use them to accurately predict outcomes. Another not-extreme-at-all example where quantum physics completely breaks down is empty space. However, this discussion is deliberately missing the point, which is that it's not making predictions in everyday scenarios where physics fails. It's in describing the basic nature of our universe, which are two completely different things all together.

You're right that there are examples of scientists who highlight these gaps in our knowledge, there are more who simply pay some lip service to them, and then there's a much larger group of people, like dbasedweeb, who irrationally suppress all criticisms of scientific theories as if they were literally religious beliefs.

[dbasedweeb]

I want you to engage in a thought experiment. I don’t code, and couldn’t program my way out of a wet paper bag. I assume that you can do much better than that, right? If I try to bullshit you about something you know a great deal about, from my position of ignorance, how long would it take for you to realize that I just knew little bits and pieces, but not the big picture? A sentence? Two?

And yet you seem to think that when it comes to physics, this same rule won’t apply. If you really care about the subjects you’re talking around, take some intro courses, really learn about it, or accept that you can only bullshit people who know less about the subject than you.

Phrases like, “the basic nature of our universe” sound good if you don’t know the first thing about the topic at hand, and probably impress people with no education or experience on said topic. To others, they’re huge giveaways that you don’t know what you’re talking about. Other red alerts are, “What is space?” “Empty space” and broad, substance-free critiques.

If you care about the subject and not just projecting a particular image of yourself, then bother to actually learn about them beyond the level of pop science. Critiquing something you demonstrably don’t have a deep knowledge of is a pointless exercise unless you’re just trying to impress people who know even less about it than you.

Here are some resources.

Intro To SR: https://ocw.mit.edu/courses/physics/8-20-introduction-to-spe...

Intro to GR: http://www.staff.science.uu.nl/~hooft101/lectures/genrel_201...

Further reading on GR: Gravitation by Misner, Thorne, Wheeler.

Intro to QED: http://sophia.dtp.fmph.uniba.sk/~peterp/QED_A.pdf

http://hepwww.rl.ac.uk/hepsummerschool/Evans%2008%20Intro%20...

https://www-thphys.physics.ox.ac.uk/people/FrancescoHautmann...

Intro to QFT: QFT Demystified is a great starting point...

Quantum Field Theory by Claude Itzykson and Jean-Bernard Zuber

Anything by Zee, especially “For The Gifted Amateur”