What is Gravity? No-One Knows!

Zilch5

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#32
A Scientist Takes On Gravity

But what if it’s all an illusion, a sort of cosmic frill, or a side effect of something else going on at deeper levels of reality?

So says Erik Verlinde, 48, a respected string theorist and professor of physics at the University of Amsterdam, whose contention that gravity is indeed an illusion has caused a continuing ruckus among physicists, or at least among those who profess to understand it. Reversing the logic of 300 years of science, he argued in a recent paper, titled “On the Origin of Gravity and the Laws of Newton,” that gravity is a consequence of the venerable laws of thermodynamics, which describe the behavior of heat and gases.

“For me gravity doesn’t exist,” said Dr. Verlinde, who was recently in the United States to explain himself. Not that he can’t fall down, but Dr. Verlinde is among a number of physicists who say that science has been looking at gravity the wrong way and that there is something more basic, from which gravity “emerges,” the way stock markets emerge from the collective behavior of individual investors or that elasticity emerges from the mechanics of atoms.

Looking at gravity from this angle, they say, could shed light on some of the vexing cosmic issues of the day, like the dark energy, a kind of anti-gravity that seems to be speeding up the expansion of the universe, or the dark matter that is supposedly needed to hold galaxies together.

Dr. Verlinde’s argument turns on something you could call the “bad hair day” theory of gravity.

It goes something like this: your hair frizzles in the heat and humidity, because there are more ways for your hair to be curled than to be straight, and nature likes options. So it takes a force to pull hair straight and eliminate nature’s options. Forget curved space or the spooky attraction at a distance described by Isaac Newton’s equations well enough to let us navigate the rings of Saturn, the force we call gravity is simply a byproduct of nature’s propensity to maximize disorder.

Some of the best physicists in the world say they don’t understand Dr. Verlinde’s paper, and many are outright skeptical. But some of those very same physicists say he has provided a fresh perspective on some of the deepest questions in science, namely why space, time and gravity exist at all — even if he has not yet answered them.

“Some people have said it can’t be right, others that it’s right and we already knew it — that it’s right and profound, right and trivial,” Andrew Strominger, a string theorist at Harvard said.

“What you have to say,” he went on, “is that it has inspired a lot of interesting discussions. It’s just a very interesting collection of ideas that touch on things we most profoundly do not understand about our universe. That’s why I liked it.”
The rest of the article is here:

http://www.nytimes.com/2010/07/13/scien ... gewanted=1
 

rynner2

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#33
Thanks for posting that, Zilch.

Very interesting, but it's as woolly as a lorryload of sheep on the way to market! Even Prof Verlinde doesn't seem too clear about it. But as he says “It’s not often you get a chance to say something new about Newton’s laws. I don’t see immediately that I am wrong. That’s enough to go ahead.”

He said friends had encouraged him to stick his neck out and that he had no regrets. “If I am proven wrong, something has been learned anyway. Ignoring it would have been the worst thing.”

And that's how science works.

Another quote I like was from Dr. Padmanabhan: “Gravity is the thermodynamic limit of the statistical mechanics of 'atoms of space-time.'”
I'm thinking of having that tattooed on my arm... ;)
 

ChrisBoardman

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#36
I'll use this as my defence if ever i decide to drop a railway sleeper from a motorway bridge onto a passing car....

seriously, it's rubbish
 

craunch

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#39
If gravity doesn't exist, then neither does levity. A lack of levity would mean that these emoticons would not exist :D :) :lol: , but I can include them in this reply, therefore gravity must exist because its opposite, levity does. ;)
 

Ringo

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#41
My first reaction on reading this topic title was "Of course it bloody does!"

Then I re-read it and saw that it said Gravity - not gravy.
 
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#42
Pietro_Mercurios said:
SHAYBARSABE said:
Xanatic_ said:
So what causes space to wrap around the mass of the Earth, as you phrase it?
Cats. It's always cats.
It's the static build-up in their fur. That's why they have to rub themselves against things all the time.
But by strapping buttered toast, buttered side up to a cats stomach and back and then dropping the cat, you will create an anti-gravity device.
 

Cochise

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#43
The guy who wrote Dilbert (Scott Adams?) years ago put forward semi-humourously the theory that there is no gravity - the universe (and everything in it) is in fact expanding in all directions at 32ft per second but because its all expanding at exactly the same rate we are unable to notice it directly, we only notice the acceleration which we feel as 'gravity'.
 

stu neville

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#44
Kind of similar to Robert Rankin's theory of why some ghosts appear annually - they're immune from the effects of gravity, and so basically float around in space but within the path of Earth's orbit - then once a year, the Earth runs smack into them so we see them fleetingly :).
 

Xanatic_

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#45
To me it seems you've mixed up wormholes and Einstein's theories of gravity as space time curvature. If space was folded into a circle like you say, wouldn't you expect light to be moving in circular orbits like the planets as well?
 

James_H

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#46
There's a quotation in How Mumbo Jumbo Conquered the World by Francis Wheen, from - an English Enlightenment Philosopher, and I'm racking my brains unsuccessfully trying to remember who - which is pretty much a joke on this subject.

Something to do with an increasingly abstract philosophical discussion going late into the night - A raises doubts about the reality of gravity; B invites A to step through the window if so sure of his premises.
 

EnolaGaia

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#47
There's a quotation in How Mumbo Jumbo Conquered the World by Francis Wheen, from - an English Enlightenment Philosopher, and I'm racking my brains unsuccessfully trying to remember who - which is pretty much a joke on this subject.

Something to do with an increasingly abstract philosophical discussion going late into the night - A raises doubts about the reality of gravity; B invites A to step through the window if so sure of his premises.
The reference was to David Hume's Dialogues Concerning Natural Religion, at the opening of Chapter 4. There's another reference to Hume jesting about this later in the chapter.
 

Yithian

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#48
The reference was to David Hume's Dialogues Concerning Natural Religion, at the opening of Chapter 4. There's another reference to Hume jesting about this later in the chapter.
Hume was known for good cheer: he ate and drank a lot and would often booze into the night with his friends.

'Abstract philosophical discussion going late into the night' might well be tongue in cheek.
 

EnolaGaia

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#51

EnolaGaia

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#53

INT21

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#55
I find that clicking on the links gives me a couple of paragraphs of text then a message saying I need to subscribe if I want to continue reading the item.

I am tempted to subscribe for the on-line version. I gave up the paper version as it was belt tightening time.
 

Comfortably Numb

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#56
I find that clicking on the links gives me a couple of paragraphs of text then a message saying I need to subscribe if I want to continue reading the item.
I don't, as in:

1549924688291940.jpg

Maybe something to do with, 'cookies' from a previous visit to the web site?
 

Comfortably Numb

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#58
Continued.... if you type in that URL, it does indeed take you to the 'subscribe' invitation... however, if you search for, 'new scientist gravity', the article is duly highlighted and that link evidently bypasses the subscription requirement.
 
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