Exploring the Feasibility of Laser-Based Ram Scoops Powered by Micro Black Holes [closed]

Question

Ram scoop ships are a well-loved element of hard science fiction, typically employing magnetic fields to harvest interstellar gas. However, this concept often grapples with practical issues like drag and other dynamic interactions.

My latest musings have pivoted towards utilizing feedable artificial micro black holes as a sustainable power source. With a black hole mass around half a million (actually 50 to 500 billion) tons, we could theoretically harness hundreds of petawatts of energy, giving the black hole a lifespan of several years.

Given such a potent energy reservoir, I'm curious about the feasibility of a laser-based ram scoop that eschews traditional material components in favor of a conical laser configuration. This setup would involve forward-facing lasers—potentially in the ultraviolet, X-ray, or gamma ray spectrum—to ionize interstellar gases.

The idea is to utilize Coulomb scattering, with the lasers angled approximately 40 degrees relative to the vessels’s vector, aiming to direct the protons down the collector’s throat. These protons could then be harnessed as reaction mass or even fed into the black hole.

However, I'm unsure about the physics underpinning this concept, particularly the momentum transfer between photons and protons and whether Coulomb scattering would efficiently collect interstellar hydrogen in front of the vessel over a significant area.

Has anyone delved into the mechanics of such a system, or can shed light on whether this laser-based approach could physically function as intended?

EDIT 1: I only care about the feasibility of the laser based collection scoop. The details of the rocket do not matter. This is not a frame challenge, this is about one little physics trick with photons and protons.

EDIT 2: Here is the paper I am referring to. The science behind this is better than behind any warp drive. I messed up my mass estimation. I want a black hole between 5 and 50 Billion tons. About the mass of a medium asteroid. And similar in size to a proton.

Answer 1

Drag is exponential to your velocity

Any mass you absorb at relativistic speeds will have to be accelerated to the speed of your ship to become part of it. So depending on how efficient your engine is, your terminal velocity is really easy to find using a simple E=MV² calculation:

Efficiency | Terminal Velocity 90% | 0.810c 80% | 0.640c 70% | 0.490c 60% | 0.360c 50% | 0.250c 40% | 0.160c 30% | 0.090c 20% | 0.040c 10% | 0.010c

How this compares to a ship without a Ram Scoop

If we instead assume a negligible drag on a ship and instead just plan to use up the black hole's mass as a fuel source, then we can look at this more like a Mass to Energy conversion. If a ship weighs 10,000 tons and has a 500,000 ton blackhole for fuel that radiates as light, then we can express this as a ship that weight 510000 tons and averages 250000 tons of mass as energy to speed up and then again to slow down. This gives you base Mass to Energy conversion rate of about 49%. Your efficiency is then multiplied by your conversion rate to offset the efficiency of your drive system and then you take the square of that to find your peak velocity expressed as a fraction of the speed of light. This yields the following table of Maximum velocities showing that a ramscoop, despite its drag, should be capable of peak speeds approximately 3-4 times as great as a shp without:

Efficiency | Terminal Velocity 90% | 0.194c 80% | 0.152c 70% | 0.116c 60% | 0.084c 50% | 0.063c 40% | 0.040c 30% | 0.023c 20% | 0.010c 10% | 0.003c

Other Considerations

The most efficient lasers in the world are only about 50% efficient. So how ever much wattage your black hole is putting out in thrust, you can assume your ship is absorbing at least that much in heat which will need to be radiated over time. On top of that, you have to be very careful not put out so much energy over time that you splatter your crew accelerating too quickly. This means you need a much larger black hole than the 500,000 tons originally posed (I see that the OP updated the mass of his black hole to 5 and 50 Billion tons; so, I'm assuming he already realized this.)

Consequently, a ram scoop will give you a much higher peak speed, but may have a lower acceleration depending on where your ship bottlenecks. If the design of your ship is such that your blackhole is limited by how fast you can radiate heat, then a scoopless ship could have a higher acceleration since it does not need to have a higher output to overcome drag. However, if your ship can radiate heat fast enough that harmful rates of acceleration are possible, then both styles of ships can be engineered to have the same rate of acceleration regardless of how much drag there is.