Found in 2 comments on Hacker News
raattgift · 2017-02-10 · Original thread
Really? So what's the gravity term in the Standard Model Lagrangian? [1]

> Page one of any book of the Standard Model discusses the 4 fundamental forces. Guess what one of them is: GRAVITY.

Well, let's just test this assertion of yours.

Right at hand I have Halzen & Martin [2] and "gravity" appears in the index (on p. 389) pointing to pp 27 and 348. Section 1.8 (pp 27-28) explains why gravity is not addressed in the book, and at p. 348 there is a brief discussion following the Weinberg-Salam unification scale at eq 15.58 about whether, given it is large, the gravitational interaction can still be neglected. The treatment there is unsurprisingly fully classical.

Maybe you don't like this particular textbook.

How about Cottingham & Greenwood [3]? This is an excellent book aimed at grad students, and has the advantage of having its introductory chapter online:

Quoting:

https://ned.ipac.caltech.edu/level5/Cottingham/Cott1_1.html

"The Standard Model excludes from consideration the gravitational field."

Well, at least that's on page one.

Who next? How about Griffiths [4]? In the middle of page 50 we find:

"This is all adding up to an embarrassingly large number of supposedly 'elementary' particles: 12 leptons, 36 quarks, 12 mediators (I won't count the graviton, since gravity is not included in the Standard Model)."

Above are three standard textbooks introducing the Standard Model, and they all support my assertion and not yours.

Let's see, here's another item for your consideration: https://home.cern/about/physics/standard-model

"The Standard Model includes the electromagnetic, strong and weak forces and all their carrier particles, and explains well how these forces act on all of the matter particles. However, the most familiar force in our everyday lives, gravity, is not part of the Standard Model, as fitting gravity comfortably into this framework has proved to be a difficult challenge"

I would be very keen on any evidence that supports your claim that the Standard Model is not mute on gravity.

I'd also be keen on what else you believe I was "hillariously wrong" about. I'd be happy to expand upon, back, or source most of the statements as I do here, if you particularize your complaints and are reasonable and polite about it.

And finally, what really are you trying to accomplish here?

[1] here's Cottingham & Greenwood's[3] write-down of the SM Lagrangian:

http://einstein-schrodinger.com/Standard_Model.pdf

which provides the straightforward answer that there is no gravity term.

[2] https://www.amazon.co.uk/Quarks-Leptons-Introductory-Particl...

[3] https://www.amazon.com/Introduction-Standard-Model-Particle-...

[4] https://www.amazon.com/Introduction-Elementary-Particles-Dav...

dehowell · 2010-11-10 · Original thread
You've got to get some statistical mechanics on this list. One would have a very difficult understanding quantum field theory without at least some experience considering phase transitions in more familiar settings.

Feynman's Statistical Mechanics is a pleasant read: http://www.amazon.com/Statistical-Mechanics-Lectures-Advance...

I used to be an experimental particle physicist, so I've certainly got some bias here, but I really think learning particle physics and the Standard Model is worth while. Halzen and Martin is a VERY good textbook and an excellent preparation for studying quantum field theory.

http://www.amazon.com/Quarks-Leptons-Introductory-Particle-P...

Yes, it is expensive. But it is very well written and thorough.

Also, I think it's always important to mention in these conversations that most physicists don't take string theory seriously. From the outside, it looks like the exciting frontier of modern physics. But that's more about Brian Greene's skill in marketing himself than string theory's explanatory value.

That being said, the Fabric of the Cosmos is a good layman's survey of the modern physics landscape:

http://en.wikipedia.org/wiki/The_Fabric_of_the_Cosmos

Just bear in mind that Greene makes a lot of claims that aren't experimentally justified in chapters 12 and onward.

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