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Comments

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Mars (One) Needs Payloads

photonic Re:Payloads? Here's what I would like to see. (77 comments)

As you said, the low density of air at Mars might be a problem. The theoretical maximum power that can be harvested with a wind turbine is P = 1/2 * rho * A * V^3. Some numbers from Nasa show that the density rho is about 1% of the value on Earth, and an average speed of 10 m/s (around 5 Beaufort) is also not exceptional. Finally, you will need a relatively big mechanical device, which is hard to build light and reliable, since it has to survive a rocket launch.

about three weeks ago
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Update Your Shelf: BitLit Offers Access To Ebook Versions of Books You Own

photonic What could possibly go wrong (82 comments)

Great, one guy who actually owns the book takes a high resolution scan and puts it on the internet, everyone else prints it out and signs it ....

about a month ago
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Making an Autonomous Car On a Budget

photonic Re:Just 2 models of Audi? (61 comments)

Electrical power steering is much more common than you assume, especially in the last few years. I know that at least my 8 year old smallish European car has an electrical one.

about a month ago
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SpaceX Injunction Dissolved

photonic Mission accomplished (98 comments)

I don't think Elon expected to win that easy, but look how much publicity he got for filing a simple claim and getting a temporary injunction. He got to say a few times how they are 4x cheaper than the old guys, that might be remembered by some press and politicians the next time there is a big contract up for grabs.

about 3 months ago
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Feds Issue Emergency Order On Crude Oil Trains

photonic Similar incident in Italy (211 comments)

There was a similar incident in Viareggio 5 years ago: a train carrying LPG derailed and crashed into a platform in the center of town during the night. The resulting explosion killed 32 people and destroyed a whole block of houses. In this case it was LPG, not crude oil, so I guess a tiny leak would have been enough to cause problems. You would have to make the tanks extremely strong to prevent that. And there is even other dangerous goods, there were some nasty accidents with trains carrying chlorine, which doesn't need fire to kill people.

about 3 months ago
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Ask Slashdot: How To Back Up Physical Data?

photonic tin foil hat (245 comments)

Since having this nightmare, I've exported my phone's VCF file to an online repo, made online notes of all my bank account numbers and passport ID, I keep ICE numbers with me at all times (separate from phone/wallet), and I've hidden a spare mobile phone and house key in a box in a nearby field. But there must be more to do!

I think the only thing left to do is buying loads of a aluminium foil.

about 3 months ago
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SpaceX Files Suit Against US Air Force

photonic Bloody rocket dealerships (176 comments)

It is about time that the FTC steps in and allows SpaceX to sell their rockets directly to the Air Force. Blame the rich local rocket dealerships, we corrupted their local politicians to create laws that are only designed to maintain their business model of selling old fashioned rockets. What people in the street want is to buy a next generation rocket, directly from the Internet, without having to talk to one of those sleazy rocket salesman. I am getting confused, you were saying Elon?

about 3 months ago
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Most Expensive Aviation Search: $53 Million To Find Flight MH370

photonic Re:Tracking` (233 comments)

Data charges would be much less than that, $20 extra per ticket would be unacceptably high. Some spokesman for Inmarsat (who obviously has a big interest in making permanent data connections mandatory) said that data costs for such a flight would be on the order of 1$/hour for the whole aircraft. Data rates should also be pretty low, 1 GPS coordinate per minute would have helped enormously for both the AirFrance and MalaysiaAirlines crashes, the detailed high-bandwidth data you can always get from the black box if you can find it.

about 4 months ago
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Your Car Will Tell You How To Hit the Next Green Light

photonic Re:Part of this is a late April fools joke. (364 comments)

True story: The lecturer that taught us general relativity at university was a fantastic guy that was also pretty good at drawing cartoons. For one of the questions on the final exam, he drew a scene of a guy being stopped by a policeman: "I am stopping you for crossing the red light." "I saw it as green, I swear officer." "Fine, then I will write you a ticket for speeding." The question was to calculate the speed of the car, given the wavelengths of green and red light and the velocity of light.

about 4 months ago
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Adaptation From Flash Boys Offers Inside Look at High-Frequency Trading

photonic Re:Forbit all HFT (246 comments)

contribute to society except for profit for themselves

Your opinion, fortunately we aren't slaves to one person's opinion as to what is valuable "to society". I am sure all the employees, their families, children, dogs, etc. of the HFTs, producers of all the networking and computing gear they use, the buildings and home they inhabit, the doctors they visit, and so on, might disagree with you about the lack of contribution to society.

That is a bad argument: People making money with organized crime spend money on employees, family and goods too, but that does not make it a good thing. If the HFT people would not be skimming billions of dollars from the market, millions of people might have received 100$ more since their pension fund would have done slightly better, and they would have spent it the same. What did the HFT contribute to society to rip off all those people?

about 4 months ago
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Adaptation From Flash Boys Offers Inside Look at High-Frequency Trading

photonic Re:Forbit all HFT (246 comments)

The question is if it is not too late to introduce regulations. These leeches probably made enough money to corrupt Congress for the next 100 years.

about 4 months ago
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Adaptation From Flash Boys Offers Inside Look at High-Frequency Trading

photonic Forbit all HFT (246 comments)

HFT should be banned, there is nothing these robo-traders contribute to society except for profit for themselves. The argument that they provide for liquidity of the market, or whatever, would not change if everyone would be trading at second scale instead of microsecond scale. My proposal (as someone how knows nothing about stock markets): make it a level playing field and only allow trading at say exact 30 second intervals or so, which should be synced world-wide. In this way, the big firms would only have an advantage over the small guy when new information becomes available in the last half second before the deadline, instead of on every instance of new information. After everyone has placed their orders for the current round, the stock market then takes a few seconds to update all stock prizes, after which everyone has 'infinite time' to compute his action for the next round.

about 4 months ago
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Last Week's Announcement About Gravitational Waves and Inflation May Be Wrong

photonic Re:Jumping the gun (194 comments)

Scientist are still analyzing the data of ESA's Planck satellite, with first results expected in October this year. This instrument is supposedly sensitive enough to confirm or reject BICEP's results. I guess Planck's team must feel pretty depressed that the potential big discovery of their 700 MEuro instrument is scooped by the relatively small-scale BICEP experiment.

about 4 months ago
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Big Bang's Smoking Gun Found

photonic Indirect measurement of gravitational waves (269 comments)

Note that this the second indirect evidence for the existence of gravitational waves, the first one was the orbital decay of a binary system that included a pulsar, discovered by Hulse and Taylor (Nobel Prize 1993). Today's result, if confirmed, seems pretty spectacular, and might be rewarded with a second Nobel Prize. For a first direct detection of gravitational waves, we have to wait for first detections by LIGO, Virgo and eLISA.

about 4 months ago
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The Earth As a Gravitational Wave Detector

photonic Re:Resonant Detector (70 comments)

The LISA project has a long history, with several iterations of down-sizing its costs, and at some point the Americans pulled out of the project completely. The latest version of the project is called ELISA, which was recently approved as ESA's L3 mission in 2034. A bit late, but better than nothing ...

about 5 months ago
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Ubuntu 14.04 Brings Back Menus In Application Windows

photonic Re:Oh thank god (255 comments)

Exactly. I like the global menu in general, but almost once a day I close some underlaying window by accident, since it still has focus.

about 5 months ago
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What Are the Weirdest Places You've Spotted Linux?

photonic Multimedia overlay on ruins in Rome (322 comments)

Last year, I visited the Palazzo Valentini in Rome, which is just a few steps away from Piazza Venezia and within falling distance of Trajan's column. They dug up some Roman remains of houses and temples in the basement of a more modern building. They did quite some effort to make it into a multimedia show, with beamers projecting accurately aligned overlays of all kind of things that had disappeared. One cool effect was for example to extend a mosaic, of which only a small piece was left, over an entire room. I was observing how the tour-guide started the shows, he was just launching a VLC player or so on a linux box sitting in a rack in the corner. From the looks of the icons, it was probably an older version of Ubuntu (8.04 or 10.04).

about 6 months ago
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EU To Allow 3G and 4G Connections On Planes

photonic The point: hear safety announcements (106 comments)

There are two reasons you have to switch of your electronic devices during takeoff/landing: first, the electronic interference, which is not considered a problem anymore these days. The second, more unknown, reason is that they do not want you to listen to music so that you can hear the safety announcements. I am not talking about the usual 'live-vest is stored under your seat' story that everyone has heard 100 times, but instructions to evacuate in case of real emergencies. Since these emergencies happen mostly during the first and last few minutes of a flight, they want you to pay full attention. Source: close friend is instructor for flight crews.

about 9 months ago
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SnapChat Turns Down $3 Billion Offer From Facebook

photonic Re:They're ALL on crack. (188 comments)

With $3B at stake, that would be pretty risky poker play for Facebook. If Facebook knows it is a boondoggle, it is likely that SnapChat's owners know it too, so their best action would be to take the money and run.

about 9 months ago
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SpaceX Falcon 9 Blasts Off From California

photonic Reusable first stage? (97 comments)

I watched the webcast live. The qualification of the upgraded Falcon 9 seemed to have gone very well, with payloads deployed in nominal orbits. They were also supposed to do some first tests for recovering the first stage. The only thing that I could find was that the second of two burns after separation sent it into a spin, after which it crash-landed in the ocean. Anyone has some more news about that?

about 10 months ago

Submissions

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Possible collision between cube-satellite and old space junk

photonic photonic writes  |  about a year ago

photonic (584757) writes "The BBC is reporting about a possible collision between Ecuador's first satellite (a small cubesat) and debris from an upper stage of an old Russain rocket. If confirmed, this might be the 3rd case in recent years, after a high-speed collision of an Irridium satellite with a dead Russian satellite in 2009 and a collision earlier this year between a Russian laser reflector (which can be tracked very accurately) and a tiny piece of a debris of a Chinese weather satellite that was destroyed in a missile test."
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Man extradited to the US after uploading child-pornography to MS SkyDrive

photonic photonic writes  |  about a year and a half ago

photonic (584757) writes "The national Dutch broadcaster reports (Google translate fails due to cookie warning) that a man living in Amsterdam was extradited to the US for the production of child-pornography. The man is a US citizen and the offenses were allegedly committed in the US and other countries, so the extradition seems uncontroversial. The interesting detail is that the man was apparently caught after he uploaded some of the offending files to Microsoft SkyDrive. Are the authorities actively scanning all your files or do they simply give Microsoft (and Dropbox, Google, ...) a list of hashes of known illegal material?"
Link to Original Source
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NIST releases report on WTC 7 collapse

photonic photonic writes  |  more than 5 years ago

photonic (584757) writes "After a 3 years of study, NIST finally released its report on the collapse of World Trade Center building 7. The main conclusion is that the building came down due to fire, not due to debris damage or some conspiracy demolition team. The fire started pretty small after the collapse of WTC 1, but was left to burn several floors out completely. The important finding is that the collapse was triggered by thermal expansion of beams, which could detach asymmetrically loaded girders from the main columns. Some limited pancaking of floors than caused lack of lateral support and buckling of a single column. This triggered the failure of the entire core of the building, which finally fell down as a single piece. Crackpot theories can be discussed in the Digg comments, so please limit the discussion to the science here. All documents can be found here, which read like a porn magazine for finite element junkies. Awesome movies are here. And yes, they used Beowulf clusters to do the simulations, some of which lasted for several months."
Link to Original Source

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