Starshot's speed limit

Centauri Dreams exists to tout the Breakthrough Starshot, a mission to Alpha Centauri at 0.1-0.2C. Unfortunately this didn't get a dedicate team at the time, which was, what, the late 1990s such that we'd be getting data now. The fact of it taking 20 years tends to keep Congress (and any republocratic system) from greenlighting such a thing, like those Uranian missions we don't got (Voyager was politically-feasible only because it promised to relay data from Jupiter and Saturn en-route).

The one bit of tech that did get some work was the solar sail itself, having some local applications as it does. IKAROS went to Venus in 2010; ACS3 is in operation in NEO now. This blog has recommended solar-sails for 50ish AU targets, like Eris.

Suppose we could iterate that tech toward something faster. 0.75C (... like Passengers) means 5.66 years (Einstein & Copilot say 3.75y on-board). Senators - in particular - might be talked into that one, especially new Senators.

Engineering issues abound: for instance, light gets redshifted as the sail vanishes away, but we might fix that with a fleet of boosters, which expend their last enthalpic battery pulses punching out one last laser. Up to Jupiter, these expendable boosters can be "3U Plasma Magnets".

There's also dust. I expect that's more a worry at Oort and not interstellar (at present).

The real issue is a background photonic speed limit. We've discussed that here for cosmic rays and, uh. Something like it applies to Starshot too.

Assuming complete unobtainium and space-magic for everything short of warp, the sail is only getting to 0.75C. At that point diffuse scattering begins acting as drag. That's cutting it thin for our Senate.