[tatjam]

You can't use a solar sail for this, but if you use lasers, you can get a few newtons / GW of incident laser power. Sci-fi stuff but if you can make a very very light reflector that can somehow be cooled (microscopic IR dipoles come to mind), and a very very focused and powerful laser, you can go a long way. Not sure what the purpose of moving a thin metalized foil at a fraction of lightspeed would be, though :)

[kimixa]

Yeah, many of the theoretical solar sail ideas fall down on what I consider a useful "probe" is, and what it can mass. As mentioned in my other comment, if you define the "probe" to be "a single particle" we /already/ do this all the time in particle accelerators. But it's clearly not a useful "probe" I believe the original thought experiment implied. A few hundred grams of super thin solar sail material is still very much in the "Not A Probe" definition in my mind.

Plus even the best laser dispersion quickly gets significant at the distances required to give the sail the time to accelerate at such a low thrust.

[floxy]

Roundtrip Interstellar Travel Using Laser-Pushed Lightsails

https://ia800108.us.archive.org/view_archive.php?archive=/24...