General Weapons of the future.

[JohnCalyn]

If I am reading your syntax above correctly, you seem to be using 3.336 x 10^9 m/s for your value of lightspeed. Lightspeed is 3.0 x 10^8 m/s. I believe there is also an additional factor of 2 in your numerator.

You're right twice: I entered the 2 twice, and the speed of light is 3x10^8 (always double check!) According to SBCL (Lisp) the result is now 2384.692 meters.

That makes the corrected code (if it's correct this time):

(/ (* 1.989e30 6.67e-11 2) (* 3.33564e8 3.33564e8)) ~= 2384.692 meters, or 2.38 kilometers, more or less.


However, I think the point still stands: It is a black hole and that means by definition there is an event horizon.

 

[mike wightman]

c is close to 300,000km/s - or the distance light travels in one second.

Which is 3x10^5 not 3x10^6 - converting to metres that gives 300,000,000 or 3x10^8

so (2xGxM)/c^2

plug in very rounded numbers so I can do the calculation in my head

(2 x 7x10^-11 x 2x10^30) / 9x10^16 = 3x10^3 or 3km.

 

[whulorigan]

Google says the Sun (1 Solar mass) is 1.989 × 10^30 kg. At 4.5 x 10^6kg you might get away with it, but (again, according to google...FWTW) that isn't a Solar mass. I hope I'm not repeating someone else's nitpick.

That makes the corrected code (if it's correct this time):

(/ (* 1.989e30 6.67e-11 2) (* 3.33564e8 3.33564e8)) ~= 2384.692 meters, or 2.38 kilometers, more or less.


However, I think the point still stands: It is a black hole and that means by definition there is an event horizon.

You have missed my point entirely. I am not debating whether or not the sun can be made into a black hole with sufficient density, nor that the critical Schwarzschild radius of the sun is anything other than ~3 km, if one were to attempt to do so thru matter-compression. My point is that we are looking to create a "gravitational" (or "pseudo-gravitational") focusing lens for a space combat laser. The point raised earlier up-thread is that 30g ought to be sufficient to cause the necessary deflection of light to create such a hypothetical lens.

If we were to talk in terms of actual normal gravitation, a 4.5 x 10^6kg (= 4500 tonne) body that is 1.0 mm in radius would produce such a 30g field at its surface. And that body would NOT be a black hole, as its actual radius is orders of magnitude larger than its theoretically calculated Scwharzschild Radius.

But artificial gravity in the OTU is NOT actual normal gravity, but rather some as yet currently unknown "spin-off" pseudo-gravitational effect that reacts to and is affected by mass-energy. So you would not need to create a collapsed-matter body as noted above in the first place, since standard pseudo-gravity fields within starship interiors can already be constructed to produce 6g-9g without the creation of any large masses as a field source. All you would need to presuppose would be some means of multipying that pseudo-gravity field by a factor of 3-5 in a very small localized area at a certain distance in front of the laser muzzle.

 

[mike wightman]

So why not use this pseudo-gravity projector as a weapon?

 

[whulorigan]

So why not use this pseudo-gravity projector as a weapon?

Conceptually you could, but I think pseudo-gravity in the OTU is presumed to be very short range, falling off rapidly over a relatively short distance. My knee-jerk reaction would be that the "intense focusing node" might only be viable to be projected tens of meters from the emitter(s), maximum. This would fall far short of the thousands of km typical of tactical weapon ranges.

The same could be said about the concept of a tractor beam more generally. It may be possible (maybe even common) to have a short range projector as a sort of "tow-cable" at higher TLs for certain vessels, but creating a tactical tractor beam that could operate against an adversary at tactical weapon ranges in order to restrict maneuver and agility would be something else entirely.


Note however that in T5 there are weaponized Tractor/Pressors at base TL16:

T5.10 Book 2, p.164:

Tractors and Pressors (reversed polarity versions of the same principle) are grav-based remote manipulators. Each is capable of applying pressure (tractors pull an object toward it; pressors push an object away from it; each is capable of applying some lateral pressure).

Standard Mode. The Weapon function of Tractor/Pressor creates a violent shaking motion which destroys components.

Tractor Mode. The Tractor/Pressor can attach to an object and hold it in place; effectively locking the Tractor and its Target at a specific Range (typically Boarding Range).

Anti-Missile Mode. The Tractor/Pressor in Anti-Missile Mode deflects incoming missile attacks by diverting their courses.

• For the "Standard Mode" above, depending upon the frequency of the oscillation and fine tuning, this could alternatively provide the basis for a projected/induced "sonic disruption" effect in the target.
• The "Anti-Missile Mode" above forms the basis for the CT: High Guard "Repulsor" (or "Deflector", depending upon your terminology preference).

 

[whulorigan]

... standard pseudo-gravity fields within starship interiors can already be constructed to produce 6g-9g without the creation of any large masses as a field source. All you would need to presuppose would be some means of multiplying that pseudo-gravity field by a factor of 3-5 in a very small localized area at a certain distance in front of the laser muzzle.

Also note that you would only need to multiply that pseudo-gravity field by a factor of 3-5 very briefly in order to create the lensing effect as the laser is being fired; it would not have to be continuously "on".

 

[Spinward Flow]

Also note that you would only need to multiply that pseudo-gravity field by a factor of 3-5 very briefly in order to create the lensing effect as the laser is being fired; it would not have to be continuously "on".

In a pulse laser, sure.
In a beam laser ... you're looking at a longer duration application (by definition).

 

[whulorigan]

In a pulse laser, sure.
In a beam laser ... you're looking at a longer duration application (by definition).

Yes, but a BLaser duration is still relatively brief (all things considered), the pseudo-gravity lens would still not be "always on" (or even "long duration" on). (And BLasers in general are introduced at 1-TL higher than PLasers, IIRC).

In T5.10 Book 2:

• Mining Laser: Base TL8. Mining Laser is an industrial-strength laser system created for asteroid mining. Its primary use is slicing nickel iron asteroids at relatively close ranges. *
• Pulse Laser: Base TL9. Pulse Laser is a weaponized Mining Laser with improved power and damage. It fires in intermittent pulses rather than continuous beams.
• Beam Laser: Base TL10. Beam Laser is the standard starship Laser weapon. It fires in continuous beams to increase the gunner’s chance to hit.

​

* (Probably no significant focusing needed)​

 

[JohnCalyn]

You have missed my point entirely. I am not debating whether or not the sun can be made into a black hole with sufficient density, nor that the critical Schwarzschild radius of the sun is anything other than ~3 km, if one were to attempt to do so thru matter-compression. My point is that we are looking to create a "gravitational" (or "pseudo-gravitational") focusing lens for a space combat laser. The point raised earlier up-thread is that 30g ought to be sufficient to cause the necessary deflection of light to create such a hypothetical lens.

If we were to talk in terms of actual normal gravitation, a 4.5 x 10^6kg (= 4500 tonne) body that is 1.0 mm in radius would produce such a 30g field at its surface. And that body would NOT be a black hole, as its actual radius is orders of magnitude larger than its theoretically calculated Scwharzschild Radius.

But artificial gravity in the OTU is NOT actual normal gravity, but rather some as yet currently unknown "spin-off" pseudo-gravitational effect that reacts to and is affected by mass-energy. So you would not need to create a collapsed-matter body as noted above in the first place, since standard pseudo-gravity fields within starship interiors can already be constructed to produce 6g-9g without the creation of any large masses as a field source. All you would need to presuppose would be some means of multipying that pseudo-gravity field by a factor of 3-5 in a very small localized area at a certain distance in front of the laser muzzle.

I'll grant OTU 'gravs' are not 'gravities'. I made & have already agreed to that elsewhere. I did misread your intent. Apologies.

But it still seems like a lot of unnecessary effort and power for anything short of a spinal mount laser of such power that it simply cannot be focused by more 'material' means.

Of course, that's probably what you're getting at....

 

[infojunky]

So why not use this pseudo-gravity projector as a weapon?

You mean like Repulsers?

Short range Tractors are part of the setting.

 

[aramis]

I'm sketching in from a couple of google searches:

The formula for the Schwarzchild Radius is:

A short, rough (and classical) lisp program to calculate this, plugging in values for G, M(Sol) and c returns a Schwarzchild Radius for Sol at:

(/ (* 2 6.67e-11 1.989e30 2) (* 3.33564e9 3.33564e9)) = 23.846918 meters

This is not quite a 1mm point source. You definitely have an event horizon. And the gravity is definitely greater than 28G at that radius. At 1mm you're probably in a completely separate universe...as an expanding wave of hard radiation.

Do I have my math right?

M=1.989e+30 kg
G= 6.6743e-11 in m³ kg⁻¹ s⁻² (to 5 significant digits (and is imprecise at 6)
c=2.99792458e8 m/s
c²= 8.9876e16 to 5 sig digits

R=2 × 1.989e+30 × 6.6743e-11 / 8.9876e16
R= (2 × 1.989 × 6.6743 / 8.9876) × 10⁽³⁰⁻¹¹⁻¹⁶⁾
R=2.954110708086697×10³
R=2964.1 m = 2.964e3 m = 2.964 km
A solar mass black hole would have about 3 km. This matches the Wikipedia page's table for the sun at 2.95e3 within 2 places precision,

You moved decimal on C 8 places, but wrote it as 9 places, and had c wrong.

However...
Using https://www.ajdesigner.com/phpgravity/gravity_acceleration_equation_planet_mass.php#ajscroll to get a 2cm 30 gee for the mass it spits out 44105745886.161 kg so 4.4106×10¹⁰ kg

M= 4.4106e10 kg

R= (2 × 4.4106 × 6.6743 / 8.9876) × 10⁽¹⁰⁻¹¹⁻¹⁶⁾
R= 6.5507×10⁻¹⁷m

So, no, 30 gee at 1cm radius is not a singularity.
It is, however, more than the gravitics can generate per the rules.

Schwarzschild radius | Definition, Equation, & Facts

Schwarzschild radius, the radius below which the gravitational attraction between the particles of a body must cause it to undergo irreversible gravitational collapse. This phenomenon is thought to be the final fate of the more massive stars (see black hole). The Schwarzschild radius (Rg) of an

www.britannica.com

Gravitational constant | Definition, Value, Units, & Facts

Gravitational constant, physical constant denoted by G and used in calculating the gravitational attraction between two objects, which is equal to G times the product of the masses of the two objects divided by the square of the distance between them. The value of G is 6.6743 x 10^-11 m^3 kg^-1...

www.britannica.com

Speed of light | Definition, Equation, Constant, & Facts

Speed of light, speed at which light waves propagate through different materials. In a vacuum, the speed of light is 299,792,458 meters per second. The speed of light is considered a fundamental constant of nature. Its significance is far broader than its role in describing a property of...

www.britannica.com

 

[whulorigan]

But it still seems like a lot of unnecessary effort and power for anything short of a spinal mount laser of such power that it simply cannot be focused by more 'material' means.

Of course, that's probably what you're getting at....

The issue is really the standard distances at which combat occurs in Traveller. Traveller Space Combat can easily occur at distances of thousands to 10s of thousands of kilometers. Laser beams do in fact spread with distance (even though it is very slight). But at combat distances, it becomes significant. A beam that starts out from the turret-muzzle at 1cm in diameter can easily be a meter or more in diameter by the time it reaches the target. But the beam energy remains constant, meamning that the amount of energy per square-cm falling on the target decreases with the increase in diameter. So your high power laser ends up being a flashlight beam by the time it strikes the target without extreme focusing. And the power of the laser at the muzzle would be high enough to melt or vaporize a lens made of conventional materials (remember that to be a weapon, the beam must be powerful enough to blast thru starship hull/armor).

During the Apollo missions in the early 1970s, a laser was fired from the Earth to a reflector that had been set up by a Lunar Lander crew on the Moon to precisely measure the Earth-Moon distance. The pencil thin beam was a number of meters in diameter by the time the beam reached the moon.

 

[kilemall]

The issue is really the standard distances at which combat occurs in Traveller. Traveller Space Combat can easily occur at distances of thousands to 10s of thousands of kilometers. Laser beams do in fact spread with distance (even though it is very slight). But at combat distances, it becomes significant. A beam that starts out from the turret-muzzle at 1cm in diameter can easily be a meter or more in diameter by the time it reaches the target. But the beam energy remains constant, meamning that the amount of energy per square-cm falling on the target decreases with the increase in diameter. So your high power laser ends up being a flashlight beam by the time it strikes the target without extreme focusing. And the power of the laser at the muzzle would be high enough to melt or vaporize a lens made of conventional materials (remember that to be a weapon, the beam must be powerful enough to blast thru starship hull/armor).

During the Apollo missions in the early 1970s, a laser was fired from the Earth to a reflector that had been set up by a Lunar Lander crew on the Moon to precisely measure the Earth-Moon distance. The pencil thin beam was a number of meters in diameter by the time the beam reached the moon.

My assumption with HG battery is it’s the multiple beams overlapping, raising the overall probability of penetration.

 

[mike wightman]

You mean like Repulsers?

Short range Tractors are part of the setting.

No, I do not mean repulsors. I mean these magic tunable massive "gravity" fields being used to make weapons. One has already been mentioned - instead of a magnetic coil accelerating a projectile you would use consecutive "laser focusing grav field generators" to fire a projectile,

And short range "tractor beams" have flip flopped TL over editions. they are very difficult to pin down as to their existence in the OTU at the usual TLs...

 

[mike wightman]

My assumption with HG battery is it’s the multiple beams overlapping, raising the overall probability of penetration.

That won't work as well as you think. The laser is spreading out over an area - ie two dimensions, while you are only increasing the number of lasers, or one dimension, you would need to square the number of lasers in a battery not just add them - and even I know I have explained that pretty badly.

 

[Grav_Moped]

That won't work as well as you think. The laser is spreading out over an area - ie two dimensions, while you are only increasing the number of lasers, or one dimension, you would need to square the number of lasers in a battery not just add them - and even I know I have explained that pretty badly.

Beam dispersal reduces energy delivered to target by (something multiplied by) the square root of distance, right? That is, it's lighting up an area that's a small part of the inside of a sphere, and that area increases as the square of diameter (A=4*pi*r²).

Adding lasers increases energy delivered to target linearly by increase in number of weapons.

On the other hand, it also increases the danger space linearly if they're not all aimed (and focused) at the same point in space, so the odds of a hit (contact) go up linearly while not necessarily increasing the chances of penetrating the target hull. It's a tradeoff between energy density at the target versus size of the danger space.

 

[mike wightman]

To properly model a laser with the sort of energy input a Traveller laser has there should be several range bands for it. As you get closer it goes from being a search light, to a heat lamp, to cutting torch, to a... laser cutter

Worse it gets more accurate as you get closer so if you have a 40% chance to hit at a few tens of kilometres, by the time you are only a thousand kilometers away you are automatically hit.

 

[BackworldTraveller]

So how much bending does passing through a 30g field for 3.33^10-9 seconds actually give? Not much. And that is assuming a 1m "Barrel". OK you don't need much but it really isn't much.

 

[mike wightman]

I don't know where the 30g figure came from, I always thought it would require thousands of artificial g to 'focus' the laser in the machinery/optics of the laser, the alternative is the gravity is projected few thousand km away.

 

[BackworldTraveller]

On the basis of S=UT+.5AT^2 and A is 300 with U=0 and T^2 = 1.11x10^-17 then it deflects 0.00000001 nanometres. Is that enough? Really?

I guess the quantum world and Einstein will muck that number up somewhat but it's still small.