Laser Launch into Orbit

> Naturally, a rocket going into space cannot carry along an electrical wire to the ground to deliver energy.

I’ve been wondering about this actually. (Please keep an open mind if responding)

In theory if we used a high enough voltage. Possibly in the megavolt range we could have a very lightweight wire. And if we could turn that directly into heat on the rocket without even needed equipment to step it down.

I don’t see why we couldn’t have long wires. At least 20 miles and use it as a low speed first stage.

You underestimate how insane the power requirements of a high-g launch are. Placing one ton into orbit requires a rocket with close to 1GW peak power output (this is only a very rough figure that depends on mass ratio, thrust and exhaust velocity). Delivering this much power over 20 miles, even at 1MV, would take about a ton of aluminium wire (again, very roughly). The weight grows quadratically from there -- delivering this much power 200 mi downrange to the upper stage would take 100 tons, even setting aside all the other technical challenges. And this is where we actually want this power delivered -- we don't need to increase the ISP of the first stage, as it is mostly wasted in the exhaust anyway. An ISP above the capability of chemical propulsion is beneficial in the upper stage only.