Ammo For Space Combat

[Guest aevans]

http://en.wikipedia.org/wiki/Maser

 

IIRC light is a special thing, having the properties of a wave and a particle both. I shouldn't say much, because I'm not thoroughly enough versed to argue pedantics.

141871[/snapback]

 

Not really. X-rays, gamma rays, microwaves, ultraviolet, visible light, infrared, and radio frequency radiation are all carried by photons. Photons have certain special properties: zero mass -- or at least theory predicts them to be massless, and no one has experimentally demonstrated otherwise -- propagation speed at exactly the speed of light, and "energy" equivalent by "wavelength".

 

I put energy and wavelength in quotes because how a particle can have no mass and still transmit energy and how a single particle can demonstrate wavelike behavior have not been fully explained by theory. That being said, mathematical functions that treat photons as waves and derive their energy based on wavelength do predict observable phenomena.

[Guest aevans]

Antimatter drives might not be as far off as you think. While pure antimatter drives will require alot of antimatter, various antimatter fusion/fission hybrid drives requires far less amounts of antimatter. Antimatter Initiated Microfusion drives (AIM) and  Antimatter Catalyzed Micro Fission/Fusion drives (ACMF) requires no more antimatter than we can produce with current technology.

141883[/snapback]

 

And, if you have enough antimatter to sling around, AM particle beams would make pretty good weapons, provided you could focus their output and target the enemy efficiently. Think of a mondo TV electron gun firing positrons...

[DB]

http://en.wikipedia.org/wiki/Maser

 

IIRC light is a special thing, having the properties of a wave and a particle both. I shouldn't say much, because I'm not thoroughly enough versed to argue pedantics.

141871[/snapback]

 

"Light" isn't special for this reason - it's special because the eyeball, mk1 mod 0 can detect it.

 

What the things actually are doesn't matter - one applies the photon model (e.g. when examining the photoelectric effect) at one time and the wave model at another (when looking at diffraction, for example.)

 

On the use of lasers for cooling - this method was described in the David Brin novel "Sundiver" to cool the eponymous vessel as it skimmed the sun's corona.

 

The cooling mechanism I really didn't get was Alastair Reynolds cryo-arithmetic engines in Absolution Gap.

 

David

[Lentzner]

According to Dictionary.com:

 

Light:

 

# Physics.

 

1. Electromagnetic radiation that has a wavelength in the range from about 4,000 (violet) to about 7,700 (red) angstroms and may be perceived by the normal unaided human eye.

2. Electromagnetic radiation of any wavelength.

 

I suppose I prefer b. since a. is a pretty inexact (scientifically speaking) definition. People say "Ultaviolet Light" which is not detectable by the eye and according to definition a. would be a contradiction in terms.

 

I would quibble a bit with your description, Tony. Light has can be described as both a particle and a wave, but it does not, according to the Heisenberg Uncertainty Principle, exibit both properties at the same time. Just to make it all the more confusing, light can also be described as a wavelet or wave-packet - a piece of a wave.

 

There's still many mysteries to be solved such as how a wave can propagate without a propagation medium and how a massless particle can be affected by gravity.

 

Regards,

 

Matt

[Guest aevans]

I would quibble a bit with your description, Tony...

141931[/snapback]

 

All I said was that a photon exhibited wavelike behaviors, and that it's energy was derived from treating it mathematically like a wave. Both of these statements are true. If I forgot to also mention that wave and particle treatments were mathematically mutually exclusive, well excu-u-use me-e-e.

[gewing]

I remember a proposal to use what was basically a net with DU or Tungsten beads at each intersection....

 

 

There is sense to this.  But why stop at only two spheres?

 

Or why use spheres at all?

 

An "X" of wire, if encountered at sufficient velocity, could be expected to do great damage.  It would also have a fairly wide "capture" area.  But perhaps a more complex shape, like a square of wire, or an asterisk-shaped wire, would give higher probabilities of striking what an "X" would pass as a near miss.

 

The key difference in space is that you can accelerate the same mass to the same velocity almost regardless of its density or shape.  (There are some complications in HOW you accelerate a large area mesh evenly, but presume for a moment that those are accounted for).

 

So what would we expect the difference in damage to be between being struck by a 1cm diameter sphere of 10g mass travelling at 50,000kph, versus a 5m x 5m mesh of wire with 10g total mass travelling at that same velocity?

 

I would expect that only a small portion of the total area of a space combat ship would actually be life-support chambers.  A much larger portion of the ship would be propulsion and navigation, and an even larger portion would be fuel storage (or solar arrays) and sensors.  It is harder and harder to pay the penalty for armor as you go from the small "inhabited" parts to the wide open "gathering" parts.

 

Even IF you could some how armor the core of the ship, a strike by a 10g mesh would probably be a crippling blow.  A single 1cm spere would have a much larger probability of missing critical systems.

 

-Mark 1

140398[/snapback]

[DB]

All I said was that a photon exhibited wavelike behaviors, and that it's energy was derived from treating it mathematically like a wave. Both of these statements are true. If I forgot to also mention that wave and particle treatments were mathematically mutually exclusive, well excu-u-use me-e-e.

141947[/snapback]

 

One of my favourite "WTF?" moments in physics is the double slit diffraction experiment.

 

The overall distribution pattern of the photons that come through a double slit fits the wave theory, but if you stop down the emitter you can get single photon events recorded on the detector side.

 

If you wait long enough, the distribution of photon events *still* cannot be explained by the photon particle model, it needs the wave model to work.

 

So, you have an experiment that shows single events (photons hit the detector in specific locations, they don't get smeared out individually), and yet, the overall pattern can only be explained by the other model. Seems to me that this experiement shows both behaviours actiing simultaneously.

 

I maintain that the mathematical characterisation of the universe is merely a model of the universe's behaviour. The universe might well have Maxwell's demon sitting by the slit with a photonic baseball bat taking very carefully aimed swings at the passing photons. The mathematics only describes the *result*, not the *mechanism*, and even then it only approximates the solution, for we have as yet no pefect "theory of everything".

 

But then I only just scraped through my physics degree.

 

David

[Lentzner]

One of my favourite "WTF?" moments in physics is the double slit diffraction experiment.

 

The overall distribution pattern of the photons that come through a double slit fits the wave theory, but if you stop down the emitter you can get single photon events recorded on the detector side.

 

If you wait long enough, the distribution of photon events *still* cannot be explained by the photon particle model, it needs the wave model to work.

 

So, you have an experiment that shows single events (photons hit the detector in specific locations, they don't get smeared out individually), and yet, the overall pattern can only be explained by the other model. Seems to me that this experiement shows both behaviours actiing simultaneously.

 

I maintain that the mathematical characterisation of the universe is merely a model of the universe's behaviour. The universe might well have Maxwell's demon sitting by the slit with a photonic baseball bat taking very carefully aimed swings at the passing photons. The mathematics only describes the *result*, not the *mechanism*, and even then it only approximates the solution, for we have as yet no pefect "theory of everything".

 

But then I only just scraped through my physics degree.

 

David

141958[/snapback]

 

David,

 

There is no contradiction because, even though you are seeing both characteristics of light you are seeing them in different contexts. Heisenberg says that if you know the position of the particle then you cannot know it's wavelength, and vice versa. Basically, you can't observe it without changing it. Knowing the position is knowing where it was. You were seeing the pattern made as a group without knowing the individual particulate properties.

 

I too had the WTF during the double slit experiment. My professor told us a story about someone observing the wave effect with electrons. So they decided to release one electron at a time and using a coil to detect the electrical field, determine which slit the electron passed though. Once they did this, no more diffraction pattern. I am still trying to get my head around that one.

 

As far as being a physics whiz, I'm with you. Solid C average as an undergrad with no desire to continue. Once things got too tiny to see, I was hopelessly lost.

 

Matt

[Ssnake]

One of my favourite "WTF?" moments in physics is the double slit diffraction experiment.

My wife still doesn't believe me that electrons get to "know" when they're being watched. OK, maybe I fooled her once too often (e.g. when in France they had Summertime and in Switzerland not, and we crossed the border and told her that it was due to time zone shifts as we were travelling eastward, and that "swiss watches work differently". I could hold my face for about a minute, but then I almost had to stop the car.

I guess that was the moment when distrust crept into our marriage. Took me years to work it out, and I think there still is a tiny crack. Uh-oh...

[DB]

David,

 

There is no contradiction because, even though you are seeing both characteristics of light you are seeing them in different contexts. Heisenberg says that if you know the position of the particle then you cannot know it's wavelength, and vice versa. Basically, you can't observe it without changing it. Knowing the position is knowing where it was. You were seeing the pattern made as a group without knowing the individual particulate properties.

 

I too had the WTF during the double slit experiment. My professor told us a story about someone observing the wave effect with electrons. So they decided to release one electron at a time and using a coil to detect the electrical field, determine which slit the electron passed though. Once they did this, no more diffraction pattern. I am still trying to get my head around that one.

 

As far as being a physics whiz, I'm with you. Solid C average as an undergrad with no desire to continue. Once things got too tiny to see, I was hopelessly lost.

 

Matt

141974[/snapback]

 

On that last note - my least favourite WTF Physics moment is the reflection from a potential well thing. A wall, yes, but a trench?

 

Until I see *intra-system* propulsion ideas that could generate reasonably high fractions of the speed of light (maybe enough to give a 1% mass increase - around 14% c, I believe), I'm going to assume that we can stick with Newton for our SWAGs.

 

David

[Josh]

Jua,

The heat problem could at least be partialy solved with using energy converters to power your laser and beam away your heat if the laser is reasonably effective.

I do not think that astroids will be a solution as they will be comperativly hard to move into orbits. Much easier to saturate the area with satelites instead of using your lift to move a single astroid.

 

Antimatter drives might not be as far off as you think. While pure antimatter drives will require alot of antimatter, various antimatter fusion/fission hybrid drives requires far less amounts of antimatter. Antimatter Initiated Microfusion drives (AIM) and  Antimatter Catalyzed Micro Fission/Fusion drives (ACMF) requires no more antimatter than we can produce with current technology.

141883[/snapback]

 

I'm not familiar with how heat could be converted efficiently into power for a laser right now, but I do agree that if could be some kind of laser emission would be effective for offloading energy. Alternatively I don't see any reason it couldn't be fed back into the ships drive system.

 

I spose moving asteroids is a very energy intensive process, but given enough time and patience perhaps solar sails or solar powered lasers could nudge something useful into a desired orbit over the course of years. Certainly using a ship as a tug boat seems preposterous. Also asteriods in existing orbits maybe sufficient; there is a ring mid system that could give could coverage for the inner plannets and extend outwards accross a similar range at least as far a Jupiter.

 

I'm no familiar with the other AM hybrids; I'll have to look them up. What advantage to they confer; are they just ways of initiating a fusion reaction?

[pluto77189]

I'm not familiar with how heat could be converted efficiently into power for a laser right now, but I do agree that if could be some kind of laser emission would be effective for offloading energy. Alternatively I don't see any reason it couldn't be fed back into the ships drive system.

 

I spose moving asteroids is a very energy intensive process, but given enough time and patience perhaps solar sails or solar powered lasers could nudge something useful into a desired orbit over the course of years. Certainly using a ship as a tug boat seems preposterous. Also asteriods in existing orbits maybe sufficient; there is a ring mid system that could give could coverage for the inner plannets and extend outwards accross a similar range at least as far a Jupiter.

 

I'm no familiar with the other AM hybrids; I'll have to look them up. What advantage to they confer; are they just ways of initiating a fusion reaction?

142773[/snapback]

 

Lasers right now have one big handicap. Heat. I think even the best solid state lasers are no mor ethan 50% effecient, the rest of the energy being heat. If some way was found to convert heat to electrisity, with great effecency, then we would have no problem dissapating excess energy. Loop it back to the lasers. Energy to lasers, heat to energy, repeat. This would reduce the excess heat to a managable level. Photons are a good way of removing excess energy - they don't require an atmosphere. they can be simply sent away, air or no air.

 

All we need is to find an effecient way of converting heat back to energy we can use.

[Guest aevans]

Lasers right now have one big handicap.  Heat.  I think even the best solid state lasers are no  mor ethan 50% effecient, the rest of the energy being heat.  If some way was found to convert heat to electrisity, with great effecency, then we would have no problem dissapating excess energy.  Loop it back to the lasers.  Energy to lasers, heat to energy, repeat.  This would reduce the excess heat to a managable level.  Photons are a  good way of removing excess energy - they don't require an atmosphere.  they can be simply sent away, air or no air. 

 

All we need is to find an effecient way of converting heat back to energy we can use.

142787[/snapback]

 

Run a coolant through the heat producing machinery, run the resulting vapor through a turbine, hook up the turbine to a generator. Not generally a doable process, because most waste heat sources don't produce enough heat. A high energy laser would probably be different.

[DB]

Run a coolant through the heat producing machinery, run the resulting vapor through a turbine, hook up the turbine to a generator. Not generally a doable process, because most waste heat sources don't produce enough heat. A high energy laser would probably be different.

142791[/snapback]

 

With really good thermal superconductors, you might be able to spread out the peak power thermal load of a (probably) pulsed laser system enough to extract the energy using thermocouples. (Well, we are talking very wild technical solutions in some parts of this thread!)

 

David