How much mass / kinetic energy behind SW and ST weapons...

[JodoForce]

In the fanfics I often see references to the SDs 'rumbling' as a turbolaser broadside creates xxx tons of recoil... is there canon evidence for this?

Same question for ST...

[Illuminatus Primus]

Massless particles still carry momentum, which results in recoil.

The barrels of the Death Star trench's defensive turbolasers generated prodigious recoil as seen in ANH.

[JodoForce]

I have trouble comprehending the amount of massless particles you need to fire to generate recoil...

What determines the momentum of a massless particle?

[Connor MacLeod]

Multi gigaton recoil based on "slave ship" and the AOTC ICS. If you want to get an idea, look over Mike's shield generators page and beam weapons page for ideas of firepower and recoil.

[NecronLord]

I have trouble comprehending the amount of massless particles you need to fire to generate recoil...

Behold SW weaponary. Now cower in fear...

[Illuminatus Primus]

I have trouble comprehending the amount of massless particles you need to fire to generate recoil...

What determines the momentum of a massless particle?

I can't remember off the top of my head. It's relativistic if I'm not mistaken.

[SirNitram]

Forumla for momentum of massless particles is U/c, where U is energy and c, of course, is lightspeed..

[JodoForce]

Yeah, coz m = E/sq(c), now I remember

Does that mean gamma rays will be bent more by gravity?

[ClaysGhost]

Yeah, coz m = E/sq(c), now I remember

Does that mean gamma rays will be bent more by gravity?

No. Gravitational lensing is achromatic.

[Vympel]

In the fanfics I often see references to the SDs 'rumbling' as a turbolaser broadside creates xxx tons of recoil... is there canon evidence for this?

Same question for ST...

Slave Ship references a Star Destroyer's weapons as having 'gigatons' of recoil.

[JodoForce]

Yeah, coz m = E/sq(c), now I remember

Does that mean gamma rays will be bent more by gravity?

No. Gravitational lensing is achromatic.

Care to explain?

[Isolder74]

Yeah, coz m = E/sq(c), now I remember

Does that mean gamma rays will be bent more by gravity?

No. Gravitational lensing is achromatic.

Care to explain?

are you sure you want that? I'm on my way to class right now but when I get back if you really want I can try my best to explain it. Just a note, it is a relativistic issue which takes while to explain.

[ClaysGhost]

Yeah, coz m = E/sq(c), now I remember

Does that mean gamma rays will be bent more by gravity?

No. Gravitational lensing is achromatic.

Care to explain?

The speed of light in vacuum is independent of wavelength/frequency/photon energy. Gamma rays travel at the same speed as radio waves. Imagine yourself in a lift (elevator), in which someone has decided to install a laser. The lift is in deepest, darkest space, and for our purposes there is no gravitational field within. The laser sends a beam of photons across the lift, from one wall to the other, and the beam is a straight line of photons travelling at c.

Now, imagine that some space-foo' attaches a cable to the lift and tows it "upwards", accelerating it. By the time a photon has crossed from one wall to the other, the lift is travelling a bit faster "upwards" than the photon is (conservation of momentum of the photon), so the photon arrives on a spot slightly lower on the wall than it did before the towing started. Scatter some chalk dust in the air, and you can see that the beam now traces a slightly curved path from wall to wall, because the photons nearer their destination wall have travelled for longer (and the lift has altered its velocity more since they left) than photons just leaving the laser. Since the photons travel at the same speed whatever their frequency, the frequency of the photons (UV, optical, IR) does not alter the curvature of the beam. Only things that affect the curvature are the force applied to (and hence acceleration of) the lift and the speed of light, which does not change in vacuum.

Now, imagine that someone moves the lift to a department store on Earth. There is now a gravitational field pulling downwards rather than a space foo' towing upwards, but the effect is exactly the same thanks to equivalence. The beam is "pulled" downwards, if you like, by the gravitational field, and again the field does not depend on the frequency because the frequency alters neither the acceleration of the lift (the gravitational field strength), nor the speed of light.

Therefore, gravitational fields do not act more on one frequency of light than another. Even so, the amount of energy required to bend light by any significant degree is very large. Stars, galaxies and clusters of galaxies will do it, but deflection angles are typically of order 10^-10 to 10^-4 degrees as you go up those three in mass.

[Isolder74]

The speed of light in vacuum is independent of wavelength/frequency/photon energy. Gamma rays travel at the same speed as radio waves. Imagine yourself in a lift (elevator), in which someone has decided to install a laser. The lift is in deepest, darkest space, and for our purposes there is no gravitational field within. The laser sends a beam of photons across the lift, from one wall to the other, and the beam is a straight line of photons travelling at c.

Now, imagine that some space-foo' attaches a cable to the lift and tows it "upwards", accelerating it. By the time a photon has crossed from one wall to the other, the lift is travelling a bit faster "upwards" than the photon is (conservation of momentum of the photon), so the photon arrives on a spot slightly lower on the wall than it did before the towing started. Scatter some chalk dust in the air, and you can see that the beam now traces a slightly curved path from wall to wall, because the photons nearer their destination wall have travelled for longer (and the lift has altered its velocity more since they left) than photons just leaving the laser. Since the photons travel at the same speed whatever their frequency, the frequency of the photons (UV, optical, IR) does not alter the curvature of the beam. Only things that affect the curvature are the force applied to (and hence acceleration of) the lift and the speed of light, which does not change in vacuum.

Now, imagine that someone moves the lift to a department store on Earth. There is now a gravitational field pulling downwards rather than a space foo' towing upwards, but the effect is exactly the same thanks to equivalence. The beam is "pulled" downwards, if you like, by the gravitational field, and again the field does not depend on the frequency because the frequency alters neither the acceleration of the lift (the gravitational field strength), nor the speed of light.

Therefore, gravitational fields do not act more on one frequency of light than another. Even so, the amount of energy required to bend light by any significant degree is very large. Stars, galaxies and clusters of galaxies will do it, but deflection angles are typically of order 10^-10 to 10^-4 degrees as you go up those three in mass.

Thanks, you saved me the trouble

[JodoForce]

Um, I thought gamma rays have more mass because they have more energy and therefore would be affected by gravitational fields more?

[JodoForce]

Err, nevermind
*remembers high-school physics classes*
*smacks himself on the head*

[Isolder74]

Um, I thought gamma rays have more mass because they have more energy and therefore would be affected by gravitational fields more?

Light does not have any mass at all

[JodoForce]

I thought we were discussing recoil from ray weapons here... (granted that SW turbolasers are not real lasers but it's still possible to get a reaction force from photons)

Which means they have mass in the relativistic sense at least

Ok gamma rays don't get bent more by gravity, I suppose it does have more reaction force than low frequency EM waves and would cause more recoil?

[Isolder74]

I thought we were discussing recoil from ray weapons here... (granted that SW turbolasers are not real lasers but it's still possible to get a reaction force from photons)

Which means they have mass in the relativistic sense at least

Ok gamma rays don't get bent more by gravity, I suppose it does have more reaction force than low frequency EM waves and would cause more recoil?

yes cause you can have more gamma rays in the same amount of wave guide space. Each photon of Gamma rays has more energy so would cause more recoil when concentrated.

[ClaysGhost]

Thanks, you saved me the trouble

No problem. However, reading the explanation again, I don't know why I wrote it like that. Everyone knows that objects in a gravitational field accelerate at the same rate, independent of mass. Hence photons, even photons with different mass-energies (frequencies) also accelerate at the same rate in a gravitational field. Since the bending is due to this acceleration, all photons are bent by the same amount in the same field, and so gravitational lensing is independent of photon frequency. Bing. The equivalence stuff was unnecessary.