5 ms·
One of my favorite ideas is having a pair of mirrors, one on the spaceship and another on Earth. Then shine a laser on the ship, it will bounce back and forth,
by cousin_it 5y ago
One of my favorite ideas is having a pair of mirrors, one on the spaceship and another on Earth. Then shine a laser on the ship, it will bounce back and forth, and eventually all the laser's energy will go to speeding up the ship. (Well, the beam will get wider, but you could probably get thousands of bounces.)
A funny twist on that idea just came to my mind: if you're flying past a black hole, having just one mirror on the spaceship is enough. Shine a laser from the ship toward the edge of the black hole just right, it will curve around and come back to your mirror, then reflect and come back again, and so on. Needs some tricky positioning of the mirror, but in principle it lets you "push" off the black hole without using rocketry.
- robotresearcher 5y ago> and eventually all the laser's energy will go to speeding up the ship. Half to the ship, and half to the Earth in the other direction, right?
- cousin_it 5y agoOh. Of course you're right.
- deleted 5y ago[deleted]
- andyxor 5y agosounds a bit like Starshot project funded by Yuri Milner https://en.wikipedia.org/wiki/Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Starshot "The Starshot concept capable of making the journey to the Alpha Centauri star system 4.37 light-years away. It envisions launching a "mothership" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude Earth orbit for deployment. A phased array of ground-based lasers would then focus a light beam on the crafts' sails to accelerate them one by one to the target speed. At a speed between 15% and 20% of the speed of light, it would take between twenty and thirty years to complete the journey, and approximately four years for a return message from the starship to Earth."
- cmrdporcupine 5y agohow does it slow itself down for entry into the alpha centauri system? seems like it would just blow past it
- dvirsky 5y agoIt doesn't. It snaps some pics, sends them back and moves on.
- codethief 5y agoActually, the Wikipedia page for the project notes in one of the subsections: > The travel times are for the spacecraft to travel to the star and then enter orbit around the star (using photon pressure in maneuvers similar to aerobraking). Not sure how trustworthy that information is but this kind of "aerobraking" at least seems possible in principle.