What are mass and energy?
Posted: Fri Feb 24, 2017 8:39 pm
Here's the latest http://willijbouwman.blogspot.co.uk
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Thank you.Greta wrote:Excellent. Presented in an original and thought-provoking way.
Schwarzschild black holes are based on solutions to Einstein's field equations. In that sense, they are mathematical entities. As such, they don't have to correspond to anything physical, nor is there any compulsion to explain how they work. If you think about string theory, for example, the idea is that there are these strings that have been vibrating for 13.78 billion years, without any explanation of what keeps plucking them. General relativity itself is based on the idea that matter warps spacetime, but there is no account of the mechanism it uses to do so. Nonetheless, GR is supported by a ton of evidence, while string theory is still waiting. It's an ontological conundrum: can the fact that something exists in mathematics mean it can exist in the physical world without having any properties that we would normally describe as physical? Yer pays yer money, and takes yer choice. Nah mate, is my best guess.Greta wrote:A question. Given the effect of rapid spin and the importance in the energy of an entity, do you think Schwartzchild (spinless) black holes are real or purely theoretical?
I think that is almost certainly the case. My hunch is that all black holes are rotating, because that at least suggests a mechanism.Greta wrote:Surely when a star supernovas the push of gravity inwards would hugely increase its spin ...?
Well, the singularity is a mathematical object in that it is the place were density becomes infinite. I'm not sure what infinite density would mean for a physical object, but yes, that's pretty much how I imagine black holes too.Greta wrote:I visualise a black hole's centre basically as an incredibly tiny and intense little thing spinning at insane speeds and exerting complex, vicious forces all around it, I suppose something like an exaggerated version of a neutron star in all respects.
Oh good, I was hoping that I wasn't flying off beam. Yes, these mathematical theoretical entities - especially mad things like singularities - seem unlikely, although there may be entities that are (more likely were) almost singularities.uwot wrote:Nah mate, is my best guess.
... Well, the singularity is a mathematical object in that it is the place were density becomes infinite. I'm not sure what infinite density would mean for a physical object, but yes, that's pretty much how I imagine black holes too.
Some nits:uwot wrote:Here's the latest http://willijbouwman.blogspot.co.uk
Indeed. The key word is pressure, after all, if the mass was in the form of a javelin, Stickman would almost certainly be dead. I will make that point clearer in the final draft.Noax wrote:Some nits:uwot wrote:Here's the latest http://willijbouwman.blogspot.co.uk
How much damage is done by mass X is not a function of its compactness. It doesn't directly follow.
A 1kg sponge if as rigid as the brick would have done equivalent damage to stickman.
Getting hit with the corner of the rigid sponge (more pressure) would have done more damage than being hit with the flat of the brick.
Creating an image for a photon is tricky, since ideally it should be able to account for the wave and particle properties they display. I take your point, but can't think of a better way to illustrate something that even the best physicists don't fully understand.Noax wrote:A UV photon has more mass (energy) than an IR one. Its shorter wavelength is not a measure of its compactness, since they don't really have a volume.
Well, there is a limit to how hard you can throw anything, of course. Even at close to c, while a ping-pong ball would make an impressive crater, I don't think it would come out the other side intact.Noax wrote:I quizzed my kids at the table: How fast must a ping-pong ball be thrown to earth to have it penetrate to the other side? The math was unimportant. Point was that if you say it can't be done, you're just not envisioning throwing it hard enough.
And you'd understand Einstein would you.HexHammer wrote:Basic info made weird. Lacks Einsteins E=MC2.
I actually really like the image. The text was what I didn't like, implying that they had the same mass (they don't) and it was a difference in density, which is meaningless for a thing without volume.uwot wrote:Creating an image for a photon is tricky, since ideally it should be able to account for the wave and particle properties they display. I take your point, but can't think of a better way to illustrate something that even the best physicists don't fully understand.Noax wrote:A UV photon has more mass (energy) than an IR one. Its shorter wavelength is not a measure of its compactness, since they don't really have a volume.
Intact? It doesn't even begin to graze the atmosphere before it is vaporized. I had two methods of deciding if one had achieved the act: 1) At least one ping pong ball worth of mass must be ejected from the far side of Earth. 2 ) Much more energy: At least 1% of the original material of the ball must eject to the far side. Not sure if this can be done since the identity of matter is not really defined when discussing particle interactions like that.Well, there is a limit to how hard you can throw anything, of course. Even at close to c, while a ping-pong ball would make an impressive crater, I don't think it would come out the other side intact.
Objections noted. Yes, there will need to be some editing done.Noax wrote:I actually really like the image. The text was what I didn't like, implying that they had the same mass (they don't) and it was a difference in density, which is meaningless for a thing without volume.
One other wording in need of change is using 'mass' where it says 'weight'. Mass is energy/inertia, and weight is a measure of force.
Thank you.Noax wrote:PS: You have a real talent with the artwork. Quite professional. I've had plenty of school texts illustrated far worse than what you're putting out.
So fat people are more (gravitationally) attractive?Harbal wrote:Mass is what fat people have an abundance of, energy is what they have a deficiency of.
As usual you have no clue what you are saying.Arising_uk wrote:And you'd understand Einstein would you.HexHammer wrote:Basic info made weird. Lacks Einsteins E=MC2.
Basic Physics made simple, it's called a sound pedagogy.
Do you? Well given that only a few physicists understand what he said I won't take your word for it.HexHammer wrote:...
..so yes I do understand what Einstein said. Most people learn, but u'll never learn.