Difference Laser/Graser

Michael Everett wrote:

namelessfly wrote:Weber was actually learning from our discussions of diffraction limitations!?!?!?

RFC does indeed pay attention to what we come up with, examples being The Great Resizing and modifying how the Grav-Pulse Comm works.

Of course, occasionally he can't help but have some fun at our expense, especially when we try to poke fun at him first.

runsforcelery wrote:That's

runsforcelery wrote:silly,

runsforcelery wrote:Michael.

See what I mean?
(For explanation of above, see this page of posts)

Can you tell me about what the modification to the grav pulse comm was?

BobfromSydney wrote:Can you tell me about what the modification to the grav pulse comm was?

In the original books of the Honorverse, gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) were described as faster than light and IIRC, instantaneous.

At the time the original books were written, no one had determined that gravity actually propagates at the speed of light.

When a real life scientific experiment showed that gravity (waves?) propagates at the speed of light, David changed the way that gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) radiate to producing ripples along the next higher hyper band's wall. (For normal space, this is the alpha wall.) Still FTL (albeit slowed down from instantly), but a different mechanism for gravitic sources radiate in the Honorverse.

Vince wrote:

BobfromSydney wrote:Can you tell me about what the modification to the grav pulse comm was?

In the original books of the Honorverse, gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) were described as faster than light and IIRC, instantaneous.

At the time the original books were written, no one had determined that gravity actually propagates at the speed of light.

When a real life scientific experiment showed that gravity (waves?) propagates at the speed of light, David changed the way that gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) radiate to producing ripples along the next higher hyper band's wall. (For normal space, this is the alpha wall.) Still FTL (albeit slowed down from instantly), but a different mechanism for gravitic sources radiate in the Honorverse.

I don't think the early books used the word "instantaneous" to describe the grav signals. But IIRC they did call them "realtime".

OTOH, given the range of a ship's onboard sensors is apparently under a light-hour, and you're looking at no more than a 1 minute lag on something that far out, I think it can still be plausibly called "realtime".

Whether or not RFC intended for them to be instantaneous I don't think clarifying that they were only 62x faster than light changed anything in the early books.


It wasn't until you had FTL comm relay chains (like Manticore to the Junction) that the difference between instant and 62x c became significant.

Vince wrote:

BobfromSydney wrote:Can you tell me about what the modification to the grav pulse comm was?

In the original books of the Honorverse, gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) were described as faster than light and IIRC, instantaneous.

At the time the original books were written, no one had determined that gravity actually propagates at the speed of light.

When a real life scientific experiment showed that gravity (waves?) propagates at the speed of light, David changed the way that gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) radiate to producing ripples along the next higher hyper band's wall. (For normal space, this is the alpha wall.) Still FTL (albeit slowed down from instantly), but a different mechanism for gravitic sources radiate in the Honorverse.

I believe that General Relativity says gravitational waves propagate at the speed of light. I don't think this has been experimentally verified yet -- we've been a year away from being able to detect gravitational waves for the last five years or so.

I'm not sure when RFC clarified that gravitational waves propagate at the speed of light --- in the next higher hyper band. I can't find it in The Universe of Honor Harrington, and I don't see it on the pearls site either.

JohnRoth wrote:I'm not sure when RFC clarified that gravitational waves propagate at the speed of light --- in the next higher hyper band. I can't find it in The Universe of Honor Harrington, and I don't see it on the pearls site either.

I found the one the said that it propigates as ripples along the next higher hyper wall; that was Grav pulse comm in hyper ( http://infodump.thefifthimperium.com/en ... gton/157/0 )

But the actual speed of propagation isn't mentioned there.

It's used in FTL fire control communication lag ( http://infodump.thefifthimperium.com/en ... gton/159/0 ), where it says "With the advent of Apollo, at that same range, the command-and-control loop would be 1/62nd of 46 seconds, or only .75 seconds."


But I think it's mentioned specifically somewhere in the recent books; however I wasn't able to find it quickly.

Vince wrote:

BobfromSydney wrote:Can you tell me about what the modification to the grav pulse comm was?

In the original books of the Honorverse, gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) were described as faster than light and IIRC, instantaneous.

At the time the original books were written, no one had determined that gravity actually propagates at the speed of light.

When a real life scientific experiment showed that gravity (waves?) propagates at the speed of light, David changed the way that gravitic sources (impeller wedges, hyper footprints, gravitic pulses, etc.) radiate to producing ripples along the next higher hyper band's wall. (For normal space, this is the alpha wall.) Still FTL (albeit slowed down from instantly), but a different mechanism for gravitic sources radiate in the Honorverse.

It has been known since the early 1930s that the force of gravitation travels at the speed of light. It is one of the important results of General Relativity. Some of the early observations supporting General Relativity could not be true if gravitation did not travel at the speed of light.

There have been no observations of gravitational waves. I have no idea what observations you are talking about. In any case, David Weber has made clear all along that his gravitic waves are not the same as gravitational waves.

David never said that gravitic detection acted at infinite speed--he just called it "real-time". And at the distances he was talking about at that time, it was close enough to call real-time. There is no reason to suspect that his tech book has not always specified that FTL comm acted at the speed of the next higher hyper band.

David has never specified that gravitic effects were "instantaneous". From book one it has always been ~64x light. Indeed, several key concepts and relationships in the books are predicated on this constant.

dreamrider

Leaving aside the amusing, (and so typical), scene request segment of this thread, (since when have we ever had any shower scene with anyone, even Honour's only got one inferred via background, so don't hold your breath, though i'd like to see Maeto get ahold of the culprit too:P), i think someone's missed a point or three here.

1. We know that even if a Sidewall can't bend a beam away entirely it will diffuse it. If i remember my optics right the final post beam size at a fixed range for a given diffusion is a multiple of its starting area. Which means the tighter beaming available with Grasers would seriously aid in maximizing energy density. Which would maxamise the thermal shock effect to the target.

2. If Grasers have followed the normal progression they where probably larger for their power, and maybe less efficient too. Even without the targeting differences it was probably true for a long time that you couldn't get enough Grasers for effective fire in number of shots terms even with current sensors. The tipping point was probably passed a while ago on that, but the Graysons where the first to realize it and make the relevant changes.

3. Lasers are still heavily used on the smaller combatants which are too small to carry an all up Graser. Though if the Roland's didn't have the missiles in their hammerheads i wouldn't have been surprised to see a Graser or two there instead.