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tlb wrote:

Joat42 wrote:I'm not so sure your assumption is correct about how kinetic energy is converted. Plus, considering the properties of lead - it's not a metal known for sparking regardless of any amount of mundane energy applied to it.

You have been strong on criticism, but perhaps weak on giving us a narrative of what you think happens when the bullet "hits the wall".

I wonder if that is because you will have to criticize RFC and say that he is wrong about the "fiery flash". It certainly seems as though you doubt its existence. As for me, I will insist (unless RFC makes a retraction) that lead bullets do make a flash as their structure is reduced to individual atoms by the focused gravity wall.

I have already described what happens to an object when it hits a steep gravity gradient, remember the whole "will get secondary effects due to internal friction when atoms accelerates faster than its surrounding companions plus you have atomic bonds being broken which also tend to release energy" ?

The kinetic energy a bullet has doesn't really matter because it's a miniscule amount of energy compared to what happens to the bullet when it hits a steep gravity gradient and per textev of momentum transfer, the kinetic energy is soaked up by the projectors/generators.

Joat42 wrote:I'm not so sure your assumption is correct about how kinetic energy is converted. Plus, considering the properties of lead - it's not a metal known for sparking regardless of any amount of mundane energy applied to it.

tlb wrote:You have been strong on criticism, but perhaps weak on giving us a narrative of what you think happens when the bullet "hits the wall".

I wonder if that is because you will have to criticize RFC and say that he is wrong about the "fiery flash". It certainly seems as though you doubt its existence. As for me, I will insist (unless RFC makes a retraction) that lead bullets do make a flash as their structure is reduced to individual atoms by the focused gravity wall.

Joat42 wrote:I have already described what happens to an object when it hits a steep gravity gradient, remember the whole "will get secondary effects due to internal friction when atoms accelerates faster than its surrounding companions plus you have atomic bonds being broken which also tend to release energy" ?

The kinetic energy a bullet has doesn't really matter because it's a miniscule amount of energy compared to what happens to the bullet when it hits a steep gravity gradient and per textev of momentum transfer, the kinetic energy is soaked up by the projectors/generators.

But do you believe that there is a "fiery flash" when the bullet hit the "wall"?

tlb wrote:But do you believe that there is a "fiery flash" when the bullet hit the "wall"?

I don't understand why you are asking this, I've never denied that there is a fiery flash. I've pointed out that the flash isn't due to kinetic energy being released because that would mean gravity works in an extremely wonky way in the Honorverse and that would preclude most of the gravitic tech from working at all.

By all accounts, if we gloss over the pure handwavium aspects of the technology, gravity works exactly as in the real world in most cases. Included in this is that the law of conservation is also intact for most things which is why the momentum (kinetic energy) of an object hitting a wedge is bled to the ship due to the wedge being tied to the inertial sump/compensator. For sidewalls, their generators must supply the energy directly to bleed off the momentum and when they can't keep up or fail catastrophically the sidewall is penetrated.

To instantly release an objects kinetic energy somehow you must supply a comparable amount of energy in some form instantly too for it to happen. For example, shooting down a bullet with another bullet so they fall straight down - the kinetic energy is then released mainly as heat when they hit each other.

No such thing happens when a object enters a gravity field, what happens is that momentum is transferred to/from the object responsible for the gravity field - which is why gravity assisted maneuvers are a thing. This doesn't change just because the field is artificially projected, but it can have consequences for the equipment projecting the field since just because of the law of conservation. If the gravity field also have a steep gradient it will proceed to rip things apart that enters it, regardless of any kinetic energy.

Joat42 wrote:No such thing happens when a object enters a gravity field, what happens is that momentum is transferred to/from the object responsible for the gravity field - which is why gravity assisted maneuvers are a thing. This doesn't change just because the field is artificially projected, but it can have consequences for the equipment projecting the field since just because of the law of conservation. If the gravity field also have a steep gradient it will proceed to rip things apart that enters it, regardless of any kinetic energy.

There are shear forces as the bullet enters the gravity.

However, I see a big problem with those backstops--they're in atmosphere. What happens to the air hitting it? If it's powerful enough to stop a bullet it's going to be imparting quite a velocity to the air that touches it. Where does that energy go? Why doesn't it melt whatever eventually stops it?

tlb wrote:But do you believe that there is a "fiery flash" when the bullet hit the "wall"?

Joat42 wrote:I don't understand why you are asking this, I've never denied that there is a fiery flash. I've pointed out that the flash isn't due to kinetic energy being released because that would mean gravity works in an extremely wonky way in the Honorverse and that would preclude most of the gravitic tech from working at all.

I was interested in the answer because in all your previous remarks, you seemed to be close to saying that there was no flash. It is true that you never specifically denied the flash, but you certainly seemed to mock it. That was why I previously said:

I wonder if that is because you will have to criticize RFC and say that he is wrong about the "fiery flash". It certainly seems as though you doubt its existence.

I do not know how you failed to pick up on that.

Loren Pechtel wrote:There are shear forces as the bullet enters the gravity.

However, I see a big problem with those backstops--they're in atmosphere. What happens to the air hitting it? If it's powerful enough to stop a bullet it's going to be imparting quite a velocity to the air that touches it. Where does that energy go? Why doesn't it melt whatever eventually stops it?

Pure speculation - but we do know that the Honorverse has both tractor and presser beams - might it be possible to use pressor beam projectors to keep the air back slightly from the gravity backstop? (So there'd be a small area of vacuum, or at least near vacuum, which the bullet has to pass through before it hits the grav shear)

Though the grav backstop would, presumably, still be spraying fragments or molecules of the bullets or pulser darts into something solid. They'd presumably be a bit more defuse; but probably actually have a higher total kinetic energy...

tlb wrote:I was interested in the answer because in all your previous remarks, you seemed to be close to saying that there was no flash. It is true that you never specifically denied the flash, but you certainly seemed to mock it. That was why I previously said:

I wonder if that is because you will have to criticize RFC and say that he is wrong about the "fiery flash". It certainly seems as though you doubt its existence.

I do not know how you failed to pick up on that.

Why would I pick up on something I never denied? I specifically said that you get secondary effects when something is ripped apart, I didn't think I needed to spell it out within that context that that explains the fiery flash.

The most perplexing thing about this discussion is the sheer misconceptions about how objects behave when they enter a gravity field. People should really read up on gravity and bodies with spatial extent and how gravitational gradients modifies that behavior - it's not particularly hard to understand the underlaying concepts and reason out what happens.

Joat42 wrote:Just think about the quote you gave, how fast must a 15gram bullet travel for it to produce a fiery flash when it hits something?

Joat42 wrote:That's your assumption, because the textev you gave only said the bullet disappeared in a fiery flash, and if there is one thing I know is that bullets don't do fiery flashes because of their kinetic energy unless we are talking about armor penetrating ones that relies on spalling to kill anyone on the other side of the armor.

tlb wrote:Note that I did not say the flash was due to kinetic energy, the dominant effect was the disintegration of the bullet due to gravitational forces.

Joat42 wrote:I'm not so sure your assumption is correct about how kinetic energy is converted. Plus, considering the properties of lead - it's not a metal known for sparking regardless of any amount of mundane energy applied to it.

Joat42 wrote:Why would I pick up on something I never denied? I specifically said that you get secondary effects when something is ripped apart, I didn't think I needed to spell it out within that context that that explains the fiery flash.

Well, you were wrong; you did need to spell it out (as I asked you to do at several points). The reason is the I fully expected you to deny that there was a bullet flash; since you seemed so close to doing so at several points. Had you done so; then I would happily ignore everything you said, because it did not match what the text says happened.

The one point on which we seem to agree is that there is an energy transfer between the field and the object that interacts with it.

tlb wrote:Well, you were wrong; you did need to spell it out (as I asked you to do at several points). The reason is the I fully expected you to deny that there was a bullet flash; since you seemed so close to doing so at several points. Had you done so; then I would happily ignore everything you said, because it did not match what the text says happened.

Perhaps I have been unclear, I thought we had established that there was a flash while I explicitly disagreed with that it was due to any kind of kinetic energy the object had.

The reasoning is that if no other force than gravity is affecting an object (regardless of its speed), it is in free fall. If the object is affected by a gravity gradient it creates internal stress-forces due to the gravity difference over its volume - but it's still in free fall.

tlb wrote:The one point on which we seem to agree is that there is an energy transfer between the field and the object that interacts with it.

Kind of, depending on how we view it. The basic premise is that it's the generator (that projects the field) and the object that interacts with each other through the field. Things get a bit wonky when you cram how RL gravity works into Honorverse and its gravity tech, sidewalls and such things can be likened to a gravitational body with an exotic spatial extent, wedges somewhat too but here it gets really strange since we have the compensator that is tied to the wedge and that acts like a gravity capacitor or something and there is no real world analog to use as reference for how it accomplishes that and why that makes the wedge impenetrable.

Loren Pechtel wrote:

Joat42 wrote:No such thing happens when a object enters a gravity field, what happens is that momentum is transferred to/from the object responsible for the gravity field - which is why gravity assisted maneuvers are a thing. This doesn't change just because the field is artificially projected, but it can have consequences for the equipment projecting the field since just because of the law of conservation. If the gravity field also have a steep gradient it will proceed to rip things apart that enters it, regardless of any kinetic energy.

There are shear forces as the bullet enters the gravity.

However, I see a big problem with those backstops--they're in atmosphere. What happens to the air hitting it? If it's powerful enough to stop a bullet it's going to be imparting quite a velocity to the air that touches it. Where does that energy go? Why doesn't it melt whatever eventually stops it?

Well, it was something I wondered about too. Grav-fields in an atmosphere would create some really interesting effects.

You could of course place a low-G field pointing towards the shooter just before the real backstop. That would essentially create a zone with very low air-pressure or even a vacuum.