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Comment: Re:I thought the distinction was arbitrary already (Score 1) 59

by Khashishi (#48458939) Attached to: Laser Creates Quantum Whirlpool

There are two types of mass: inertial mass and gravitational mass. As far as we know, these two are equivalent.
Inertial mass is the resistance to motion (change in velocity). In Newtonian terms, F = ma. In special relativity, F = dp/dt = d(gamma*m*v)/dt
So, you can define mass as long as you can define a velocity and acceleration.

Gravitational mass is associated with gravity. In Newtonian physics, F = -G*m1*m2/r^2. In general relativity, gravitational mass is equivalent to rest energy. Gravity is given by Einstein's field equations which depend on the stress-energy tensor, which is a 4x4 matrix. The [0,0] element of the matrix is the rest energy density, which is the gravitational mass density/c^2.

Comment: Re:I thought the distinction was arbitrary already (Score 1) 59

by Khashishi (#48458849) Attached to: Laser Creates Quantum Whirlpool

Unfortunately, the term matter isn't universally agreed upon. Let's look at the definitions in wikipedia:
1. Does it have mass and volume (occupies space)? A phonon has mass, and maybe has volume, but doesn't 'occupy space' because it is a boson.
2. relativity, has rest mass? Phonons don't fit the equation E^2 = m^2 c^4 + p^2 c^2, because they have nonlinear dispersion equations, so it doesn't really make too much sense to talk about them at rest. They aren't Lorentz invariant, since they depend on the velocity of the material they are traveling through.
3. Is it made of atoms. Phonons are not made of atoms.
4. Is it made of electrons and baryons. no.
5. Is it made of quarks and leptons? No

Comment: Re:I thought the distinction was arbitrary already (Score 2) 59

by Khashishi (#48413873) Attached to: Laser Creates Quantum Whirlpool

Matter has mass, but not all that has mass is matter. There are several types of polaritons, and some of them are clearly not matter, even though they have mass. Phonon-electromagnetic wave quanta are clearly not matter. Moreover, you state that light has no mass, which normally I wouldn't disagree with, but in the context of polaritons, what about light propagating through nonlinear media? I think it's totally appropriate to say it is massive.

Comment: Re:This isn't about technological developments, (Score 1) 200

by Khashishi (#48405661) Attached to: A Worm's Mind In a Lego Body

If, by an animal, you mean a fully developed cat or dog, then I'd argue that the animal has already reached a higher level of neural complexity than a human fetus at 20 weeks. (I can't back that up with biological data, but fetuses at that age aren't really capable of doing anything.)

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