A new idea for sandcasters...

Galactic Sapper wrote:It's at this point you should realize you've conceptually recreated the old autocannon point defense systems.

Why, yes, I do........frustrating isn't it.

Galactic Sapper wrote:It's at this point you should realize you've conceptually recreated the old autocannon point defense systems.

Brigade XO wrote:Why, yes, I do........frustrating isn't it.

To be fair, this was intended as a defense against energy weapons when transiting a wormhole, in the interval before the wedge can be brought up; something that the autocannon could never do. Perhaps the sand could be held at a distance by tractor beams, to address KZT's concern about the amount of sand needed to protect an accelerating ship.

tlb wrote:To be fair, this was intended as a defense against energy weapons when transiting a wormhole, in the interval before the wedge can be brought up; something that the autocannon could never do. Perhaps the sand could be held at a distance by tractor beams, to address KZT's concern about the amount of sand needed to protect an accelerating ship.

That's even more nonsensical! Short of introducing some sort of non-barionic matter into the universe's physics, gamma rays can't really be reflected and can barely be scattered (and the higher the energy the less scattering you get). Not to mention you need meters of solid material to stop even modest levels of gamma radiation. That's literally the in-universe (and in reality) reason grasers have so much more damage potential than the lower-energy X-ray lasers used in lesser energy weapons - the graser's gamma rays deposit energy deep into the target's armor and literally blow it apart from the inside. Depending on the energy level of the gamma rays used, some of the interactions they have with normal matter will create matter-antimatter paired particles in your armor, with exactly the result you'd expect from matter-antimatter collisions occurring.

For that matter, it's mentioned but never shown that a graser can be used to strike ground targets through a planetary atmosphere.

To be even marginally effective the sand density would have to have enough mass in the direct path of the graser to be equivalent to 5+ meters of solid concrete - and even then it's only going to stop the first shot. The first shot will dump enough energy into the sand to turn it into a mildly radioactive plasma spreading in a shock wave at relativistic speeds. The second graser would go through cleanly, since all the first shot would leave is basically interplanetary vacuum.

tlb wrote:To be fair, this was intended as a defense against energy weapons when transiting a wormhole, in the interval before the wedge can be brought up; something that the autocannon could never do. Perhaps the sand could be held at a distance by tractor beams, to address KZT's concern about the amount of sand needed to protect an accelerating ship.

Galactic Sapper wrote:That's even more nonsensical! Short of introducing some sort of non-barionic matter into the universe's physics, gamma rays can't really be reflected and can barely be scattered (and the higher the energy the less scattering you get). Not to mention you need meters of solid material to stop even modest levels of gamma radiation. That's literally the in-universe (and in reality) reason grasers have so much more damage potential than the lower-energy X-ray lasers used in lesser energy weapons - the graser's gamma rays deposit energy deep into the target's armor and literally blow it apart from the inside. Depending on the energy level of the gamma rays used, some of the interactions they have with normal matter will create matter-antimatter paired particles in your armor, with exactly the result you'd expect from matter-antimatter collisions occurring.

For that matter, it's mentioned but never shown that a graser can be used to strike ground targets through a planetary atmosphere.

To be even marginally effective the sand density would have to have enough mass in the direct path of the graser to be equivalent to 5+ meters of solid concrete - and even then it's only going to stop the first shot. The first shot will dump enough energy into the sand to turn it into a mildly radioactive plasma spreading in a shock wave at relativistic speeds. The second graser would go through cleanly, since all the first shot would leave is basically interplanetary vacuum.

I do not think that it is more nonsensical than anything else in this thread. I was merely pointing out that what was being proposed is not an iteration of the autocannon. If you were so passionate about it, why wait until now to refute the concept? The very first post suggested that it could protect from graser fire. Clearly that is wrong, if your numbers are right.

Gamma rays are significantly scattered by the atmosphere. I saw a NASA paper on high energy gamma hitting the earth’s atmosphere and basically you’d get a weapon that will kill everyone inside a square km or so. And inflict radiation poisoning beyond that. The least likely to be killed are ones behind heavy armor or lots of dirt, aka the target.

kzt wrote:Gamma rays are significantly scattered by the atmosphere. I saw a NASA paper on high energy gamma hitting the earth’s atmosphere and basically you’d get a weapon that will kill everyone inside a square km or so. And inflict radiation poisoning beyond that. The least likely to be killed are ones behind heavy armor or lots of dirt, aka the target.

Could be, for a relatively low intensity of gamma rays. Scattering would start at the top of the atmosphere and continue as the burst contacted more atoms. Most of the energy would hit fairly close to the target and drop off fairly quickly as you moved outward. The map of energy vs distance from target would be some form of bell curve.

The trick about shielding against gamma rays is that lighter atoms are just about as effective as heavier elements. A mass of graphite (or even air) will shield roughly as well as an equivalent mass of lead. In the case of the people behind heavy armor or lots of dirt, the atmosphere the gamma burst passed through is the equivalent of 65-70 cm of lead plate before it hit their bunker (if I mathed correctly).

For a longer duration and higher intensity burst, the tail end of the burst will being going through a relative void left by the ionization and explosive expansion of the air the first part of the burst hit. How that math works out is beyond my ability to calculate, but the result would have to be more radiation getting through from the tail end of the burst than the front end.

For visual reference, imagine trying to block a fire hose with a paper plate. Sure, the first bit of the stream is going to deflect and scatter, but after a few milliseconds the plate is going to lose the ability to deflect anything.

Galactic Sapper wrote:

kzt wrote:Gamma rays are significantly scattered by the atmosphere. I saw a NASA paper on high energy gamma hitting the earth’s atmosphere and basically you’d get a weapon that will kill everyone inside a square km or so. And inflict radiation poisoning beyond that. The least likely to be killed are ones behind heavy armor or lots of dirt, aka the target.

Could be, for a relatively low intensity of gamma rays. Scattering would start at the top of the atmosphere and continue as the burst contacted more atoms. Most of the energy would hit fairly close to the target and drop off fairly quickly as you moved outward. The map of energy vs distance from target would be some form of bell curve.

The trick about shielding against gamma rays is that lighter atoms are just about as effective as heavier elements. A mass of graphite (or even air) will shield roughly as well as an equivalent mass of lead. In the case of the people behind heavy armor or lots of dirt, the atmosphere the gamma burst passed through is the equivalent of 65-70 cm of lead plate before it hit their bunker (if I mathed correctly).

For a longer duration and higher intensity burst, the tail end of the burst will being going through a relative void left by the ionization and explosive expansion of the air the first part of the burst hit. How that math works out is beyond my ability to calculate, but the result would have to be more radiation getting through from the tail end of the burst than the front end.

For visual reference, imagine trying to block a fire hose with a paper plate. Sure, the first bit of the stream is going to deflect and scatter, but after a few milliseconds the plate is going to lose the ability to deflect anything.

We pretty much determined that on page 2. I, the OP, have long since agreed that the issue would not work, even in the special case I mentioned of the emergence lane. I only mentioned it because wedges could not clear "sand" in a emergence lane and ships in the lane could not out accelerate the sand while the ship transited the lane, and thus wanted to start the thought experiment.