from the first,-assume-a-spherical-cow... dept.
https://m.phys.org/news/2019-03-black-holes-conquer-space-halo.html
A lot of hopes currently hinge on the use of directed energy and lightsails to push tiny spacecraft to relativistic speeds. But what if there was a way to make larger spacecraft fast enough to conduct interstellar voyages? According to Prof. David Kipping, the leader of Columbia University's Cool Worlds lab, future spacecraft could rely on a halo drive, which uses the gravitational force of a black hole to reach incredible speeds.
Prof. Kipping described this concept in a recent study that appeared online (the preprint is also available on the Cool Worlds website). In it, Kipping addressed one of the greatest challenges posed by space exploration, which is the sheer amount of time and energy it would take to send a spacecraft on a mission to explore beyond our solar system.
[...] "So the binary black hole is really a couple of giant mirrors circling around one another at potentially high velocity. The halo drive exploits this by bouncing photons off the "mirror" as the mirror approaches you, the photons bounce back, pushing you along, but also steal some of the energy from the black hole binary itself (think about how a ping pong ball thrown against a moving wall would come back faster). Using this setup, one can harvest the binary black hole energy for propulsion."
How to travel to, create, capture, and/or contain orbiting black hole binaries is left as an exercise for the reader.
Related Stories
Space telescope would turn Earth into a giant magnifying lens
When it is finished sometime next decade, Europe's Extremely Large Telescope will be the largest in the world, with a mirror nearly 40 meters across. But one astronomer has proposed an even more powerful space telescope—one with the equivalent of a 150-meter mirror—that would use Earth's atmosphere itself as a natural lens to gather and focus light. Astronomer David Kipping of Columbia University has worked out that a 1-meter space telescope, positioned beyond the moon, could use the focusing power of the ring of atmosphere seen around the edge of the planet to amplify the brightness of dim objects by tens of thousands of times.
The atmosphere is too variable for a Terrascope, as Kipping calls it, to produce beautiful images to rival those from the Hubble Space Telescope. But it could discover much fainter objects than is now possible, including small exoplanets or Earth-threatening asteroids. Kipping acknowledges that more work is needed to prove the idea, but the necessary technology already exists. "None of this is reinventing the wheel, it just needs to be pushed a bit harder," he says.
Astronomers who read the paper Kipping posted last week on arXiv were both delighted and cautious. Matt Kenworthy, of Leiden University in the Netherlands, says he was "blown away by how much work and thought he had put into it" but wants more evidence that it will work. "I'd want to sit down and do a more realistic model," he says. Bruce Macintosh of Stanford University in Palo Alto, California, adds: "It's an interesting thought experiment, but there are a lot of details to think through."
A telescope could be put on the surface of the Moon facing the Earth (thus making both sides of the Moon attractive places to put telescopes), or at another location such as the L1 Lagrange point.
Also at Scientific American.
The "Terrascope": On the Possibility of Using the Earth as an Atmospheric Lens (arXiv:1908.00490)
Related: Sun Could be Used as a Gravitational Lens by a Spacecraft 550 AU Away
Halo Drive
(Score: 2) by MichaelDavidCrawford on Saturday March 16 2019, @07:56PM
"Recycled Boomerang Photons"?
Yes I Have No Bananas. [gofundme.com]
(Score: 3, Informative) by HiThere on Saturday March 16 2019, @08:06PM (2 children)
This idea of leaving your engine at home isn't a good idea. What happens if halfway into the mission funding is cut, or there's a revolution? The people cutting the funding don't have any investment in continuing the project, and if it's depending on photons echoing from a black hole there's going to be one hell of a lag time.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 0) by Anonymous Coward on Saturday March 16 2019, @08:11PM (1 child)
That's among the lesser risks you face.
(Score: 0) by Anonymous Coward on Sunday March 17 2019, @11:51PM
Sounds like the Halo Mary Drive.
(Score: 1, Informative) by Anonymous Coward on Saturday March 16 2019, @08:08PM (1 child)
Are the photons just getting blueshifted or is something more exotic happening?
PS: The cool worlds lab studies "extrasolar planetary systems with a particular focus on the detection and analysis of worlds found at longer orbital periods."
(Score: 2) by sjames on Saturday March 16 2019, @09:44PM
They're getting seriously blueshifted. Then they reflect back from the ship's sail redshifted and repeat.
(Score: 5, Interesting) by takyon on Saturday March 16 2019, @08:34PM (1 child)
https://www.space.com/halo-drive-black-holes-galaxy-travel.html [space.com]
godspeed?
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 3, Insightful) by mhajicek on Sunday March 17 2019, @08:56AM
Seems it would be easier to build a Dyson sphere laser with which to push your ship.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2) by sjames on Saturday March 16 2019, @09:48PM
All we need is a shoelace, 5 wasabi peas, and an Indian Elephant!
This is interesting as a thought experiment, but where the hell are we going to find a suitable binary black hole that's not further away than the place we want to have a look at?
(Score: 4, Interesting) by takyon on Saturday March 16 2019, @09:55PM
A neutron star merger can create an explosion of useful heavy elements that spread outwards. A black hole merger doesn't really do much of anything. But now we know that the merger is bad, because you could be stealing that energy for propulsion assists.
Now every time a gravitational wave detector announces a black hole merger, it is a bad day. Except you can still use a spinning black hole for this purpose.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Sunday March 17 2019, @01:29AM
LIGO claimed to detect in-spiraling binary black holes, but the signal for that looks exactly like a reversed warp drive signature (the vibrations were received in reverse temporal order). I wonder if it could have been alien tech that amounts to two mirrors spinning really fast.
(Score: 2) by crafoo on Sunday March 17 2019, @01:49AM
Every time someone mentions black hole drives I always think of that movie Event Horizon. I guess this is different though because you don't take the black holes with you? Just some mirrors? Anyway. Either way it's almost certainly a portal to hell.
(Score: 0) by Anonymous Coward on Sunday March 17 2019, @02:22PM
good thing there are blackholes else everything would be entangled. ^_^