Harris rethinks consciousness

[dannorcott]

I'm not sure I'd agree that gravity is a property of mass - rather a force that acts on mass (and lets face it, nobody really knows what it IS yet bless 'em).

[fortigurn]

Nov 15, 2011 16:51:40 GMT dannorcott said:

I'm not sure I'd agree that gravity is a property of mass - rather a force that acts on mass (and lets face it, nobody really knows what it IS yet bless 'em).

I haven't yet seen any physicist suggest that gravity is anything but a property of mass, but I'd be interested seeing any professional commentary say otherwise.

[dannorcott]

Can you find me anywhere that does suggest that? From a quick google, I can't. My understanding of it is that mass is a property of matter, and gravity is a force that acts on that mass (the most mainstream view being that it's caused by a distortion in the fabric of spacetime created by the mass).

It may just be semantics though. I was just meaning "I don't think of gravity as something produced by matter, rather a force in the universe which acts upon it".

[fortigurn]

Nov 15, 2011 17:47:22 GMT dannorcott said:

Can you find me anywhere that does suggest that?

Telford, Telford, & Geldart, 'Applied Geophysics', p. 6 (1990).

* 'Gravity is an inherent property of mass, whereas the magnetic state of matter depends on other factors'

Chubykalo, Pope, & Smirnov-Rueda, 'Instantaneous action at a distance in modern physics', p. 130 (1999).

* 'Moreover, if mass is just "condensed energy", and if gravity is a property of mass, then the energy has to have that inert gravitational property also.'

Jagerman, 'The Mathematics of Relativity for the Rest of Us', p. 52 (2002).

* 'However we must set this issue aside for a moment and just be aware that gravity appears to be a basic property of mass,'

Vanyo, 'Rotating fluids in engineering and science, p. 98 (2001).

* 'In liquid surface waves, as with the pendulum, the gravity property of mass supplies the restoring force and the inertia property of mass supplies the residual momenta that maintains the oscillation.'

Carus, 'Fundamental Problems: The Method of Philosophy as a Systematic Arrangement of Knowledge', p. 141 (2007).

* 'It is but an artificial explanation of gravity, to suppose that it is something outside of and independent of mass. The simplest conception is to consider attraction as an intrinsic property of mass.'

Southworth, 'Einsteinżs Beetle: Your Understanding of the World is About to Change', p. 116 (2008).

* 'But the point is, whether it is the Sun, the Earth, the Moon, the Space Shuttle, you, an apple or a bullet, every body attracts every other body towards its centre of gravity because gravity is a property of mass.'

[dannorcott]

heh - interesting - I've never heard it put like that. My understanding has always been more like this:

Perhaps the most unusual thing about gravity we know about is that, unlike the other forces of nature, gravity is intimately related to space and time. In fact, space and time are viewed by physicists, and the mathematics of relativity theory, as qualities of the gravitational field of the cosmos that have no independent existence. Gravity does not exist like the frosting on a cake, embedded in some larger arena of space and time. Instead, the 'frosting' is everything, and matter is embedded and intimately and indivisibly connected to it. If you could turn off gravity, it is mathematically predicted that space and time would also vanish

from: www.astronomycafe.net/gravity/gravity.html

ie. that it's just a law of physics - a property of the universe - rather than a property of matter - in the same way that I wouldn't think of the strong or weak electromagnetic forces as being properties of protons/neutrons or fermions respectively, but properties of the universe that affect these things. I'd think of gravitational pull as being a property of mass - but gravity itself as being a property of the universe/fundamental force of nature.

But I guess you can think about it either way!

[himself]

If gravity is related to space and time (space-time, actually)
And space and time do not exist in the absence of matter
Then gravity does not exist in the absence of matter.

Gravity can be expressed as a certain state of the field of Ricci tensors,
but that that is induced by the presence of mass, which is likewise a state of the field.

The Newtonian idea of "force" is obsolete. Mass produces space-time, due to the Pauli exclusion and due to its mutability. But mass bends space-time in its vicinity. This bending is experienced by other bodies as if it were a force.

[turoldus]

He is one of Dawkins's guests in the Christmas issue of The New Stasteman, with an article on "The Free Will Delusion".