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Suppose Ship A is being targeted by Ship B, which intends to use a laser weapon in an attempt to destroy Ship A.

Ship A has special technology that allows it to alter gravity (mainly used for generating artificial gravity for the crew and to lessen the effects of inertia when changing direction), but this device also allows it to increase the gravitational pull of the ship, as if it had more mass.

If Ship B points it’s laser weapon directly at Ship A and fires, and Ship A created a gravity well (similarly to an interdictor from Star Wars), could the gravity produced by the ship shield it from the laser by redirecting it via gravitational lensing?

And if so, would using this trick inadvertently (on the captain’s part) turn Ship A into a black hole?

There are several problems with this.

First of all, when someone fires a laser at you, you aren't going to know it until it hits you, so this would only work if Ship A were CONTINUOUSLY creating a gravity well in between itself and ship B. You couldn't use it reactively without letting it hit you first, although you could potentially limit the damage.

And if so, would using this trick inadvertently (on the captain’s part) turn Ship A into a black hole?

No, but in order to do this you'd have to be able to artificially CREATE a black hole, and a pretty massive one at that, in order to deflect a laser beam any meaningful distance. At that point it'd be simpler to just create the singularity right on top of Ship B and destroy it rather than mess around deflecting laser beams.

TLDR: If you can create a gravity field powerful enough to deflect a laser beam, you're so powerful you don't have to worry about deflecting laser beams.

Gravity lensing works for light paths skimming the attractor. For light paths crossing the attractor the impact would not be avoided.

So, your device would simply deviate the laser passing around the ship, not the laser hitting in.

Basically, it would work on protecting the ship only if the enemy had a poor aiming.

Depends on the range and timing.

• Ship B tracks ship A with visual sensors. Ship A has this "gravity shield" running, so the apparent position of A will be distorted.


• Ship B fires a laser at the apparent position of A, and the laser beam is distorted the same way the detection is distorted. The laser hits the actual position of A.

What you describe might work if the distances are high enough to "re-focus" the "gravity shield" between firing and impact. In that case, wouldn't there be time for conventional evasive maneuvering? So your idea calls for long range combined with an inability to dodge. Even with gravity manipulation technology, does A require fuel or reaction mass? Or is it really large?

Building off Morris The Cat's answer (because I can't comment)

If you can effectively create a black hole to "lens" a laser attack, you can just put said black hole in the path of the laser attack and have the black hole capture the light completely.

L.Dutch is correct in his answer. Increasing the mass of the ship would be useless if the enemy has good aim. It will still be hit at the center.

You could then be smart and fire a mass effect missile. The missile itself becomes more massive and deflects the laser. But how much mass would you need?

Einstein himself calculated that the Sun works as a lens with a focal distance of 542 AU's. The formula is:

$$ lensing space angle = frac4GMrc^2$$

Where $M$ s the mass of the lens, $G$ is a well known constant, $r$ is the distance from the center of mass and $c$ is the speed of light.

So at for one Earth mass, if the beam passes by the mass at a distance of 100 km:

$$ frac4 times G times 6 times 10^2710^5 times (3 times 10^8)^2 $$

That equals a whopping 2,666,666.666 x $G$ degrees. However, G has a 10^-11 built into it, so it works out to a fraction that is closer to $frac1100,000$ degrees. You'd have to go very far for that to cause a miss.

Now think about what you just did. If you are able to summon the mass of an Earth to use as defensive measure, don't use it as a lens, use it as a shield. The Earth has a radius of around 6,400 kilometers. It's more than enough to hide behind if it comes trailing at you, and massive enough that you should not be hit by the laser.

On the other hand, dispensing a cloud of aluminum foil or dust between you and the attacker would also render the laser harmless. Much lower level of entry.