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The Standard model of particle physics has a few places in which you could 'easily' insert a new particle, or lets say, that there are postulated candidates that would actually be quite welcomed.
The earth radius is 6378 km at the equator and if peak gravity occurs at about 3400 km from Earths' center, that's not close to the surface at all, it's just over half the distance to the surface.
it has to do with the total of mass as the core makes up most of earth mass.
originally posted by: Terpene
Ok, thanks for the specification.
I hope I'm at least right about this
"it has to do with the total of mass as the core makes up most of earth mass."
The solid Earth is made up of three fundamental layers, the core, mantle and crust, which are the products of planetary differentiation. The core, which is about half and Earth radius wide or only about 1/8 of an Earth volume, makes up about 1/3 of the Earth's mass
Hopefully this question seems irrelevant since the assumption upon which it was based was completely wrong. Think in terms of density. Recall this comment I made in a post I made earlier in the thread:
Lets take a planet where the mass of its denser core equals the mass of its less dens surrounding, would the mass of the less denser surrounding add to the total gravity and emanate from its surface or would we see the same discrepancies moving to the center? Where would gravity be highest?
So I gave you an example of two planets with equal mass but different surface gravity because they have different density.
originally posted by: Arbitrageur
Getting back to your question on density, the Newton formula is all amout mass and again is a pretty good approximation.
But it's based on the center of mass, so the density may affect things like surface gravity of a planet. A denser planet will have higher gravity on the surface than a less dense planet even if the planets have equal mass. This is simply because the surface is closer to the center of the denser planet.
if i had x mass, would that mass bend the fabric to the same depth no matter its density. Or does it bend the fabric more when its denser or is it only the curvature that is diffrent with diffrent density?
I wouldn't say that. Remember the example of the two planets with the same mass but different densities and different surface gravities?
originally posted by: Terpene
a reply to: Arbitrageur
a reply to: Arbitrageur
That seems to at least hint at an unaddressed answer of mine.
if i had x mass, would that mass bend the fabric to the same depth no matter its density. Or does it bend the fabric more when its denser or is it only the curvature that is diffrent with diffrent density?
Sounds like density is affecting gravity, more than mass does.
I don't really understand the question. In the example of the planets with orbiting moons above, the density matters for surface gravity of the planets, but it doesn't matter for moon orbits. One threshold in that case would be to get beyond the radius of the less dense planet, so at that distance and greater the acceleration due to gravity would be the same for both the more dense and less dense planets.
Does this apply to atoms too? Osmium being the densest material does it has the highest gravity of all materials known, and where between mass and density is the threshold. Like from what density on would you expect mass to determine gravity of other less denser mass?
In Newton's approximation gravity occurs between masses. In Einstein's model it's between masses and energy as I already explained in this thread, with a minutephysics video explaining this. So since individual atoms have mass and energy, gravity occurs even between atoms. But we don't usually talk about this much because the gravity is maybe a trillion trillion trillion times weaker than other forces, like the electromagnetic interaction, and is even weaker still from other forces, the strong and weak nuclear forces.
When we talk about gravity at Earth's surface, it's between every atom in your body being attracted to every atom in the Earth. If you go below Earth's surface toward the higher density inner core, the varying densities of the Earths' interior complicate things. It's still every atom in your body attracted to every atom in Earth, but inside the Earth you have different atoms pulling on you in different directions (or warping spacetime in different directions if you prefer), so how Earth's mass is distributed internally (which is not homogeneous) will affect the gravitational acceleration inside the Earth.
It depends on how you define "compress" I suppose, but sure gravity is a dominant form of compression which occurs in stars allowing fusion to take plase inside the star. One reason fusion power on earth is so hard to do economically is because it takes so much energy to compress and heat up the fusion reaction to conditions like the interior of a star. But there are much stronger forces than gravity like the strong nuclear force, which allows the protons and neutrons in Osmium and other heavy elements to get packed closely together, making dense nuclei.
Does matter even compress without gravity?
In the case of a star forming it's gravity which causes the disk of gas to collapse and form a star and probably all the planetisemals which will eventually form a planetary system. Again every atom gets attracted to every other atom and they all tend to get pulled together. But there are counteracting factors like the rotation of disk where "centrifugal force" prevents the total collapse and allows the planets to form.
Isn't denser matter settling towards the center because of gravity? What made it go there in the first place?
originally posted by: Direne
Oh, sure! But the problem is that most of such few places are already at the reach of current colliders' energy range, yet none of those particles have been detected. A nice example are supersymmetric partners: they should have been detected by now, but they have not (that's the problem with SUSY).
Additionally, inserting new particles causes all kind of violations (lepton number violation is the obvious one).
On the other hand, postulating new particles when the standard model has not even been able to account for neutrino masses means perhaps it's time to start from scratch reformulating a new model (the unexplained mass spectrum problem was always a caveat for the standard model). And yes, the Higgs mechanism explains how particles get mass, but it doe not explain at all why they get exactly the mass values you measure.
But even accepting dark matter consists of a yet unknown particle, the energy density of dark matter accounts for roughly one fourth of the critical energy density, so DM is not an answer to the problem by itself: you still need to justify the origin of the remaining energy density deficit, which clearly points to GR rather than QM.
Finally, the mere supersymmetrization of the SM faces an immediate problem, as I'm sure you know. The most general Lagrangian you could formulate already contains terms that violate baryon and lepton numbers producing a too fast proton decay, something which is clearly a catastrophic result. Given all this, I still prefer to exhaust the exploration of changes in GR rather than tweaking and re-tweaking , and tuning and finetuning the standard model.
So in that example of the moon orbits, planet density doesn't matter at all, it's only mass.
in the case of a star forming it's gravity which causes the disk of gas to collapse and form a star and probably all the planetisemals which will eventually form a planetary system. Again every atom gets attracted to every other atom and they all tend to get pulled together. But there are counteracting factors like the rotation of disk where "centrifugal force" prevents the total collapse and allows the planets to form.
The mass from the core onward is adding to total gravity! The gravitational acceleration at the "surface" of the core is not the "total" gravity.
originally posted by: Terpene
a reply to: Arbitrageur
So in that example of the moon orbits, planet density doesn't matter at all, it's only mass.
Why I was assuming that gravity would keep growing until there is no more mass between me and the center. So why is all the mass from the core onward not adding to total gravity when mass is the defining factor?
Here's a description of what leads to star formation, a collapse of molecular clouds.
ok, so I have a mass of not dense gas what is causing the gravity that attracts all the atoms to one singular point causing it to collapse under gravity, when every atom atract every atom and there is no significantly denser material?
It's more complicated than that, but that should give you some idea.
Molecular clouds in the interstellar medium are large. In fact, a single molecular cloud can be hundreds of thousands of times heavier than the Sun. Their volumes also vary: a molecular cloud can be the same size as, or many times bigger than, our entire solar system. These enormous molecular clouds undergo turbulent motion. This means that the gas and dust within the clouds do not stay in the same place as time passes. These substances move around in all directions, like children running around in a school yard. This turbulent motion of the gas and dust distributes the atoms and molecules unevenly, so that some regions of the molecular cloud will have more matter in them than other regions Figure 1A. If the gas and dust pile up to a very high level in a certain region, that region starts to collapse due to the pull from its own gravity. The region is smaller than the molecular cloud and lives inside the molecular cloud. The region is “only” a few hundred Astronomical Units (AUs), which is a few hundred times the distance from the Earth to the Sun.
I'm not crazy about her description of the International Space Station at 7 minutes, when she says "It has no engines anymore, the engines are turned off."
originally posted by: sarahvital
looks ok. still watching.
The mass from the core onward is adding to total gravity! The gravitational acceleration at the "surface" of the core is not the "total" gravity.
if i had x mass, would that mass bend the fabric to the same depth no matter its density. Or does it bend the fabric more when its denser or is it only the curvature that is diffrent with diffrent density?
I'm not sure this language is adequately descriptive because you're ignoring the math. At some point you should stop ignoring the math and start incorporating it into your thinking to clear this up. You say nothing about the radius here, or distance between the objects, and maybe that's part of your confusion. The radius or distance between the objects is a huge part of Newton's gravity equation and you won't have a clear description without it.
originally posted by: Terpene
Like the denser the deeper the perturbation, or is the depth the same, but only the steepness is diffrent?
Right, but the way the universe works can be complicated so we should only try to simplify it as much as it's accurate enough to meet our needs. This means sometimes the simplest interpretations don't explain everything. Newton's math explained most things for centuries, and is still good enough for explaining many things. But, it doesn't work everywhere so there's even room for making a choice of which gravity math you need to use for your application (Newton's or Einstein's).
originally posted by: Terpene
Man what satisfaction to get an ALMOST unambiguous yes from you
In geosynchronous orbit I think so, but those are stable orbits. Orbits don't have to be stable, they can spiral in or out if the momentum of the orbiting body and gravity aren't in balance.
Like just before i was looking for an answer of how long the transition takes for astronauts from sitting in their chairs to being weightless, turns out they aren't really weightless gravity is just 10% weaker at the ISS than at surface. Is the centripetal force always equal gravity?
Yes, the gravity is still there but it's usually dwarfed by other forces at that scale, electromagnetic or nuclear.
I hope I'm starting to understand a little better, I'll just postulate some things i think to have glanced so far, feel free to expand or not if I'm way off.
on an atomar scale the weak force of gravity is not really observable in its interaction and mostly irrelevant?
I suspect it's more or less determinstic but identifying all the variables is often difficult so it may seem like happenstance.
its just happenstance that a gravity center is created in non dense mass?
Confusing terminology to refer to "strong forces" since the strong nuclear force is what holds neutrons and protons together in an atomic nucleus, and such atomic nucleii are extremely dense. Gravitational interaction is considered to be an exceptionally weak force, it's about 1000000000000000000000000000000000000 times weaker than the electromagnetic interaction and about 1000000000000000000000000000000000000 times weaker than the strong nuclear force. If an interstellar medium is hot and ionized, electromagnetic forces can play a role.
the perturbation in the uniform mass creating a denser cluster with a singular gravity point is due to strong forces?
Well, it doesn't do that for the interior of the Earth does it? And you seem to be interested in things like that. It does above the surface of the Earth.
The gravity wells inverse square geometry defines gravitational acceleration?
It may sould baffling at first but it's really not. Gravity may be an extremely weak force on an atomic scale, but a body like the Earth has so many atoms that the forces of all those atoms adds up.
It's baffling that something has little influence close up but its effects reach so far, especially considering that the inverse square implies that the force is strongest from where it emits.
Simple Inverse square of the entire Earth's gravity begins at the surface of the Earth and on upward. But actually in a more complex fashion, the inverse square applies within the earth too, between every atom in your body attracted to every atom in the Earth, it's just that when you add up all those inverse square relationsips it gets rather complicated. In fact even adding a third body is more complicated than a two body problem.
Earth gravity is highest at the core surface, so is the peak/start of that inverse square graf at the surface of the core or at the center?
Center to center is a simplified calculation we can do to approximate attraction between bodies like the earth and the moon. But the real more complex way gravity works is every atom on Earth attracts every atom in the moon, it just turns out the simple equation from Newton gives a good approximation of that. Newton's approximation is no longer a good approximation when you start burrowing into the earth.
If the calculation is done from center to center, shouldn't that inverse square start at center as highest?
Perhaps gravity isn't a force at all, in fact that's one possible interpretation of Einstein's math. If your car makes a sharp right turn, you feel "forced" to the outside of the curve to the left by "centrifugal force", but centrifugal force is a "fictitious force", meaning it's actually your momentum pusing you toward the left side of the car, and momentum is not a real "force". Likewise, gravity may also be a "fictitious force", but it doesn't feel fictitious at all when you land hard after falling down the stairs. It's a matter of how we define different reference frames and real forces versus fictitious forces.
It kind of feels like gravity is just a effect of the perturbation in time space and not really a force doing anything.
It's like if you had a few pennies you wouldn't consider yourself rich. But if you had enough pennies, you would be rich, where the pennies are like the small amounts of gravity that atoms have.