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Comment: Tricky to count costs in government projects (Score 4, Insightful) 200

by joe_frisch (#47992649) Attached to: Why India's Mars Probe Was So Cheap

Its not easy to compare costs for projects done by different governments. There are different accounting standards for what is "in" and "out" of the project costs. I know nothing about the rules in India, but in Europe, scientific / engineering labor is not included in the "project". I expect the Indian probe was less expensive than a comparable NASA probe, but maybe not by nearly as large a margin as it seems.

This doesn't detract from the mission being a great success for India.

Comment: Re:Seriously, we're not rapists.... (Score 1) 595

by joe_frisch (#47767283) Attached to: New Nail Polish Alerts Wearers To Date Rape Drugs

If this is expensive (and maybe it isn't) then the question is whether this is an efficient way to spend money to reduce rapes. Its possible that other approaches (better surveillance in bars for example) could be more cost effective.

Again, I'm not objecting to this, just saying that it needs to be compared to other approaches. If it is cheap then it is probably a good solution. Even if its expensive, I think it is good to have it available to women who want to purchase it.

No question that having people stop committing rape would be great. I just don't know how to make them stop except through very indirect methods (like this one).

Comment: Re:Seriously, we're not rapists.... (Score 1) 595

by joe_frisch (#47763391) Attached to: New Nail Polish Alerts Wearers To Date Rape Drugs

I agree.
There is the possible issue that if these are expensive, then they might be oversold by fear-mongering. I do not know how common date-rape drugs are, or what this costs, so I have no opinion as to whether or not is is a reasonable (cost effective) precaution. It does seem good to have this available for women who want it.

The other possible downside is if there is a significant false-positive rate. This wouldn't lead to convictions, but could possibly destroy the reputation of innocent people. In an ideal world the drink would be sent to a lab to be tested, but most women would (reasonably) leave immediately if they thought their date tried to drug them, and would then warn everyone they knew about that person.

The second problem would be helped if the product came with a strong recommendation that the victim take a sample of the drink for real analysis any time there was a positive indication.

Comment: Re:Two categories of future tech (Score 1) 66

by joe_frisch (#47674861) Attached to: Where are the Flying Cars? (Video; Part Two of Two)

Have we really surpassed SiFi expectations? We don't have humanoid robots, intelligent computers, or unlimited longevity. We haven't cured cancer. Our computers have lots of "flops" and "gigabytes" but they don't do nearly as much as was expected in the 50s. We have moderately stronger materials, but nothing really amazing compared to 50's tech. (Ultra-strong metallic whiskers have been known for a long time). We don't have 3-d projectors in common use, and we can't 3d print our food. (mostly)

Communication is better than I think most people expected and the ubiquitousness of the internet is well beyond what was imagined.

What have we done that is so amazing - to a 1950s audience that is.

Of course science fiction is not really a good guide to the future, the writers are often not experts at what is technologically possible.

Comment: Re:Things that go fast (Score 4, Interesting) 94

by joe_frisch (#47674819) Attached to: World's Fastest Camera Captures 4.4 Trillion Frames Per Second

Most particle physics happens on much faster time scales than picoseconds. There is some slower physics but that can generally be measured by looking at the verticies where tracks diverge and calculating the time it too particles to get to those vertices.

For measuring beams rather than the individual particle collisions we can use transverse deflection structures (a sort of streak-camera on steroids) to get to resolutions of a few femtoseconds.

The original article is a nice technique, but whether it is the fastest depends on how you define "camera". It is probably the fastest for 2-d images, but there are much faster 1-d imagers.

Comment: Re:Ugh (Score 1) 201

by joe_frisch (#47603251) Attached to: NASA Tests Microwave Space Drive

The test was done in air. There are a huge number of possible sources for thrust. Most notable are convection currents from temperature differences. Even if the test is done in vacuum, you need to be very careful. Temperature changes can cause out-gassing. Thermal radiation will generate force from photon pressure.

Newtonian physics was (and still is) extremely accurate in the range in which it was tested. The flaws were found under new conditions (relatively strong fields and fast motions of planets, and detailed measurements of the speed of light).

The amount of physics knowledge now is vastly greater than it was in 1900. My day job involves working with electrons at .99999999C. As I sit here I am looking at the energy of X-rays generated from scattering off of 12 GeV electrons - getting the correct energy relies on conservation of mass energy. Conservation of mass-energy is measured in everything from planetary orbits, to electron diffraction, to neutron star binaries, to high energy collisions.

This device is not operating in any new physical regime. The energies and length scales are quite modest.There is no physical explanation of what is going on (quantum mechanics conserves mass-energy). Its a very dirty experiment (done in air etc), so it is enormously more likely to be a mistake than the discovery of a new physical principal.

Comment: Re:compared to hash database, with antivirus (Score 1) 790

Certainly anyone who emails child porn is stupid.

So if there is a child-porn detection tool, is it available to the public to automatically block an illegal images from web sites and email? I don't know if the database is just things that are obviously child porn, or includes nude pictures that are not obviously underage.

I'm not sure of the legal implications of a botnet spamming millions of people with illegal images. Most users do no know how to erase all of the copies from cache.

Comment: Re:compared to hash database, with antivirus (Score 5, Interesting) 790

Which seems like a great way to catch the minor offenders who are trading old pictures, but not the really serious offenders who are producing NEW child porn. One could even argue that it creates a market for new child porn that doesn't have known signatures.

I wonder if child porn is the only type of material that is checked against a known database?

Comment: Re:Always left out... (Score 1) 201

by joe_frisch (#47585649) Attached to: NASA Tests Microwave Space Drive

People often miss that the problem with ion drives and other electrical drives is that the exhaust velocity is too HIGH, not too low.

The higher the exhaust velocity, the more power you need for the same thrust. Making high specific impulse drives is easy - a microwave source can be ~80% efficient and has an exhaust velocity of the speed of light. The problem is that the power requirements are enormous.

Sure, energy from the sun is "free", but the mass of the solar cells to collect that energy is not free. With a speed-of-light drive the thrust to weight ration is exceedingly small for conventional power sources (which includes nuclear and solar) so the acceleration is too small to be useful for most applications.

If you imagine a solar powered spacecraft, you need to be sure that over the lifetime of the mission you would get more total velocity change out of the solar cells and electrical drive than you would from the same weight of chemical rockets. For ion drives and long missions this is true, but for a photon drive (or any other propellant-free drive it is not true for any reasonable length mission).

Comment: Re:Ugh (Score 1) 201

by joe_frisch (#47585193) Attached to: NASA Tests Microwave Space Drive

Some NASA employees are experts, but that doesn't mean that all NASA employees are experts.

If the thrust is only proportional to the photon pressure from microwaves, then this is not particularly interesting.

If the thrust is from somehow accelerating ions, electrons, or ambient air molecules, this is not particularly interesting. (just a different type of ion drive)

If there is thrust with no exhaust, if it doesn't conserve momentum, then the device is impossible.
Yes, IMPOSSIBLE. Conservation of 4-momentum is among the best tested bits of physics. "quantum mumble" doesn't change that - quantum mechanics also conserves momentum.

Comment: Re:Ok Cupid.... (Score 1) 161

by joe_frisch (#47554437) Attached to: OKCupid Experiments on Users Too

The particularly stupid part was messing with their match algorithm. If they imply that their algorithm has any value, then their users will feel at least ripped off (since the algorithm doesn't seem to work well), and possibly angry because they were given incorrect information .

Blocking pictures was visible to users and I don't have any problem with that .

Comment: Re:Suboptimal Design (Score 1) 219

by joe_frisch (#47517445) Attached to: China Plans Particle Colliders That Would Dwarf CERN's LHC

There are a variety of tradeoffs between circular and linear electron / positron machines. At very high energies (>~500GeV CM) the circular machines become impractical At low energies (100 GeV CM) a circular machine is considerably simpler and cheaper. Inbetween the trade-offs are not completely obvious.

Comment: Re:Why do you want pieces of plastic (Score 1) 354

by joe_frisch (#47509389) Attached to: Netflix Reduces Physical-Disc Processing, Keeps Prices the Same

EXACTLY.
I would much prefer streaming if the same content were available but it isn't. In particular many recent releases are only available in physical disks. If netflix wants to go to an all streaming model it needs to talk to its suppliers, not its customers .

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