mchouza
Re:Swarming Proxima Centauri: Picospacecraft Swarms over Interstellar ...
on Monday May 20, 2024 @04:06PM (#40419678)
They don't, see https://arxiv.org/abs/2309.07061 . The basic idea is to use "picosecond-level" synchronization to improve the signal-to-noise ratio. They mention that a truly phase-coherent swarm would perform much better but they consider that a longer term prospect (section 2.1.4).
Re:With the 745-Mile Solid-State Battery, Toyota Just Became a Force t...
on Sunday July 23, 2023 @06:45PM (#36840756)
Probably just converted from 1500 km.
Re:Microsoft is investing $1B in OpenAI
on Monday July 22, 2019 @11:00AM (#20498594)
I am quite confident all the current employees of OpenAI qualify as real people. They certainly have problems and probably a good share of those problems are "real" too.
Of course their priorities may be off and they could be open to be persuaded to work in a different direction. But I don't think that condescension would be very effective for that.
Re:Surprises of the Faraday Cage
on Monday August 01, 2016 @01:37PM (#12204331)
Many theoretical and experimental studies were done. One example from the early 70s is http://ipnpr.jpl.nasa.gov/progress_report2/II/IIO.PDF
Re:Drop the Supersonic Aircraft Ban
on Monday June 13, 2016 @03:22PM (#11896594)
That's true, but supersonic planes also travel higher (Concorde -> 18 km, XB-70 -> 22 km). The real problem is that L/D decreases at supersonic speeds. For example, the XB-70 had a L/D of about 7, while the 707 had a L/D over 18...
Re:Why it takes so long to get data back from New Horizons
on Tuesday February 03, 2015 @12:11PM (#8991570)
It's mostly a question of power. The 1987 design for the TAU probe communication system would have handled 20 kb/s from 1000 AU... by using between 100 and 260 watts for the transmitter (and relatively big antennas):
Re:Researchers see signature of “Majorana particles” inside supercondu...
on Friday October 03, 2014 @08:31AM (#8405189)
Photons are generally considered to be their own antiparticles: http://van.physics.illinois.edu/qa/listing.php?id=27107
Re:China's Island Factory – New islands being made in disputed China Sea
on Tuesday September 09, 2014 @10:05AM (#8290154)
Japan has more than 1000 kg of HEU: http://www.nti.org/analysis/articles/civilian-heu-japan/
Re:Wireless electricity? It's here
on Saturday March 15, 2014 @02:50PM (#7405715)
He is the first author cited in their paper:
http://www.witricity.com/pdfs/highly-resonant-power-transfer...
Re:Brazil, Europe plan undersea cable to skirt U.S. spying
on Monday February 24, 2014 @12:06PM (#7291860)
It's already public: http://www.dawn.com/news/1077275/nsa-tapped-into-undersea-ca...
Re:Former BP geologist: peak oil is here and it will 'break economies'
on Tuesday December 24, 2013 @06:44AM (#6959075)
Oil can be produced synthetically: http://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_process
Though the FT process is quite bad from a CO2 emissions POV.
Re:Ethiopian Binary Math
on Saturday October 05, 2013 @09:32PM (#6502736)
No, the algorithm as described is very different from binary multiplication. It requires a number of stones proportional to the result, while the number of bits required when doing binary multiplication is polylogarithmic.
It's a big difference: 1000 * 1000 would require 1000000 stones if done with the "Ehiopian algorithm", but it can be done with less than 1000 stones by using normal binary multiplication.
Re:Show HN: My Isometric GPU-Powered Voxel Engine
on Tuesday September 10, 2013 @09:04AM (#6359733)
Re:Russian Proton Rocket crashes Seconds after Launch
on Tuesday July 02, 2013 @12:26PM (#5978916)
You can launch from the ocean, though with more limitations: http://en.wikipedia.org/wiki/Sea_Launch
Re:Canada and science: NRC will now only do science that promotes “eco...
on Monday May 13, 2013 @04:54PM (#5701344)
Maxwell didn't come up with anything himself [...]
Maxwell "invented" the displacement current:
Re:NASA-backed fusion engine could cut Mars trip down to 30 days
on Wednesday April 10, 2013 @03:25PM (#5527466)
In the short run:
- Ion thrusters are way simpler and they are trying to do something that is much easier.
- Ion thrusters are relatively mature, working "fusors" don't exist.
- Existing machines that are trying to get fusion breakeven are building-sized.
- Trying to start a fusion reaction is hard, it only makes sense if you get a commensurate result (energy gain).
In the long run, I'm very optimistic about fusion.
Re:NASA-backed fusion engine could cut Mars trip down to 30 days
on Wednesday April 10, 2013 @12:44PM (#5526279)
Yes, I agree. My point was that you cannot do substantially better than ion engines without having energy gain and, in fact, you are probably going to do much worse due to the weight of the "fusion hardware".
I'm quite optimistic about magnetized inertial fusion. But the idea of doing the job much better than the Z-machine, with something lightweight enough to carry into space and in less than 10 years seems to me... unlikely, to put it mildly.
Re:NASA-backed fusion engine could cut Mars trip down to 30 days
on Wednesday April 10, 2013 @12:27PM (#5526156)
Well, controlled fusion hasn't reached energy breakeven at all, even taking into account the kinetic energy of the reaction products. But the low thrust of current ion engines is mostly due to power restrictions (https://groups.google.com/group/sci.space.science/msg/0cb332...). If your spaceship has a mass of one ton and you want an acceleration of 1 centigee with an exhaust velocity of 30 km/s, you will need at least:
0.5 * thrust * velocity = 0.5 * (0.1 m/s^2 * 1000 kg) * 30 km/s = 0.5 * 100 N * 3E4 m/s = 150E4 W = 1.5 MW
of power.
Re:NASA-backed fusion engine could cut Mars trip down to 30 days
on Wednesday April 10, 2013 @09:54AM (#5525128)
If fusion doesn't provide a substantial energy gain, it's not worth the effort. Existing ion thrusters are quite efficient (60+%) at translating electrical power to exhaust kinetic energy.
Re:NASA-backed fusion engine could cut Mars trip down to 30 days
on Wednesday April 10, 2013 @08:18AM (#5524611)
Project Orion was much more than science fiction (http://www.scribd.com/doc/28668567/Nuclear-Pulse-Space-Vehic...) though it was much less than operational. Very big Orion spaceships would have used fusion explosions (http://galileo.phys.virginia.edu/classes/321.jvn.fall02/Dyso...), but not the relatively small ones that were subjected to detailed analysis.
Re:Laser fusion put on slow burn
on Wednesday December 12, 2012 @12:51PM (#4911448)
Simulating explosions helps determine maintenance for nuclear warheads?
It's not completely unreasonable: they need to validate the computational models that are used to check if an aged nuclear weapon will explode.
Re:Billion-Ton Comet May Have Missed Earth by a Few Hundred Kilometers...
on Thursday November 22, 2012 @11:11PM (#4820944)
A more skeptical analysis by Phil Plait: http://blogs.discovermagazine.com/badastronomy/2011/10/17/di...
Re:Can You Stop a Hurricane by Nuking It?
on Tuesday October 30, 2012 @01:39PM (#4718453)
The basic idea is to ablate the asteroid to deflect it:
https://e-reports-ext.llnl.gov/pdf/343984.pdf
http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lare...
Re:The CIA and Jeff Bezos Bet on Quantum Computing
on Thursday October 04, 2012 @12:53PM (#4613188)
There are some places in the "natural universe" that are colder than the CMB. That's because they aren't in equilibrium:
http://en.wikipedia.org/wiki/Absolute_zero#Very_low_temperat...
Re:The CIA and Jeff Bezos Bet on Quantum Computing
on Thursday October 04, 2012 @12:49PM (#4613168)
It's not as stupid as it seems. Due to the cosmic microwave background, the equilibrium temperature far from other natural radiation sources is about 3K. But, as we don't know the temperatures in the whole universe and there are natural processes that can cool things below their equilibrium temperature, they should have said "... anywhere in the known natural universe".
Von Karman Lecture: Mars Science Laboratory's Bizarre Landing System
Re:One hiring filter that works
on Friday April 06, 2012 @01:06PM (#3807967)
The puzzle can be found at http://meshcapital.com/application.tar.gz
Re:Efficient represention for growing circles in 2D space?
on Friday January 27, 2012 @11:47AM (#3518919)
You can try posting your question in http://cstheory.stackexchange.com/
Re:Our Galaxy Has at Least 100 Billion Planets, Study Shows
on Wednesday January 11, 2012 @10:56PM (#3454979)
The paper can be found here:
http://www.eso.org/public/archives/releases/sciencepapers/es...