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Is Gravity Real? A Scientist Takes On Newton

nytimes.com

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Re: Is Gravity Real? A Scientist Takes On Newton

#21

Post by DaniFong »

michael_nielsen wrote: post #4

I haven't read the Verlinde paper, but wanted to mention one of the papers it apparently builds on. That's Ted Jacobson's remarkable paper showing that gravity is a consequence of (1) thermodynamics and (2) the black hole entropy law. The paper is http://arxiv.org/abs/gr-qc/9504004 Sabine Hossenfelder has some useful comments on Verlinde's work here: http://backreaction.blogspot.com/2010/03/gravity-is-entropy-...

Thanks for the link, Michael.

I wonder how far the link goes the other way?

One of these days, I want to try to sort out the major results and foundations in the major topics of physics in a big map, showing what has been shown to follow from what. Like the complexity zoology inclusion diagrams (http://www.math.ucdavis.edu/~greg/zoology/diagram.xml), only more general. I have the suspicion that a lot of the proofs of physics are in fact in some important way circular, but based on my first attempts I think I need to a computer to help me track all the logical dependencies.

Re: Is Gravity Real? A Scientist Takes On Newton

#24

Post by gwern »

Confusion wrote: post #14

On the one hand, gravity hasn't been 'real' since Einstein: it's a secondary effect due to the curvature of space. On the other hand, gravity has been real since long before Newton: we experience it rather directly. The editorialized title gives the impression that there are entirely new insights concerning the 'reality' of gravity and that is certainly not the case.

> "...but I have not been able to discover the cause of those properties of gravity from phænomena, and I frame no hypotheses; for whatever is not deduced from the phænomena is to have no place in experimental philosophy. To us it is enough that gravity does really exist, and acts according to the laws which we have explained."

--Sir Isaac Newton's _Mathematical Principles of Natural Philosophy_

Re: Is Gravity Real? A Scientist Takes On Newton

#25

Post by rubidium »

Qz wrote: post #6
rubidium wrote: post #5

Earlier quoted context omitted.

I got through page 11 before loosing the plot, and it seems to be a very light mathematical treatment of the subject. More of a "what if we thought about it this way?" then a "here's the proof" type paper.

Relativity started with "what if we thought about it this way?". Just saying.

Yes, exactly. That's why it's worth talking about in the first place.

I wasn't downplaying the paper, just observing what I could about the current strength of its claims. It's more of a Gedankenexperiment with some guiding equations, which it seems the author stated as his intent in the nytimes article.

Re: Is Gravity Real? A Scientist Takes On Newton

#26

Post by donohoe »

nphase wrote: post #11

Nope. Not real; I'm currently floating. Silly bogus comment aside: I hate paywalls.

  "I hate paywalls"
If you mean the NYT paywall? There is none. Yet. Being asked to log-in to a site to view content (still for free) is annoying but it is not a paywall.

Re: Is Gravity Real? A Scientist Takes On Newton

#27

Post by nphase »

donohoe wrote: post #26
nphase wrote: post #11

Nope. Not real; I'm currently floating. Silly bogus comment aside: I hate paywalls.

"I hate paywalls" If you mean the NYT paywall? There is none. Yet. Being asked to log-in to a site to view content (still for free) is annoying but it is not a paywall.

I see NYT log in screen, I immediately close the window. It's a hard habit to fix.

Re: Is Gravity Real? A Scientist Takes On Newton

#28

Post by lurkinggrue »

Confusion wrote: post #16
wlievens wrote: post #15

Earlier quoted context omitted.

"Scientist has hypothesized that gravity's origin may be somewhat different from previously considered, with no effect whatsoever on the real world" doesn't make for a very sensatinal headline.

The original headline 'A Scientist Takes On Gravity' is good enough for the NYT and therefore good enough for HN.

He took on gravity... but did gravity win?

Re: Is Gravity Real? A Scientist Takes On Newton

#30

Post by bertm »

varjag wrote: post #19
vecter wrote: post #3

Earlier quoted context omitted.

I haven't had a chance to go through the paper yet ( http://arxiv.org/abs/1001.0785 ), but it seems that he does make some derivations and proof sketches. Can someone verify this?

I'm not a physics major, but it appears superficial, non conclusive and light on math. At this point it's not a theory, but an (interesting as it may be) speculation.

This paper built upon work that Stephen Hawking did.

"The hypothesis of gravity being an entropic force has a history that goes back to research on black hole thermodynamics by Bekenstein and Hawking in the mid-1970s. These studies suggest a deep connection between gravity and thermodynamics." http://en.wikipedia.org/wiki/Gravity_as_an_entropic_force

someone might be able to find a better source.

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