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Comment: Many speed traps are published (Score 1) 457

by jschen (#46167267) Attached to: Judge Says You Can Warn Others About Speed Traps

How can it not be legal to point out a speed trap when many are announced in advance by the police department and published by local media? For example, near Des Moines, Iowa: Amusingly, one police department near Des Moines publishes the plans on their Facebook page.

Comment: short-term battery loan (Score 2) 377

by jschen (#44070405) Attached to: Tesla To Build Its Own Battery-Swap Stations

The way I see it, the best use of the proposed battery swapping isn't for a quicker charge. It's to allow one to borrow a battery to use/abuse during a road trip. If going on a long road trip, rather than subject one's own battery to the added stress of multiple fast-charge cycles, one has the option to borrow a battery for $60-80 and subject that one to those conditions. If we assume that a new battery is ca. $10k, then the rental is under 1% of battery cost. If a long road trip with multiple fast-charge cycles causes sufficient battery wear (or even just lots of anxiety about the potential effects), then for $60-80 one can get a loaner battery.

Comment: Re:How to decide the fate of helium (Score 3, Informative) 589

by jschen (#41429799) Attached to: Scientists Speak Out Against Wasting Helium In Balloons
How long do you need for a party balloon to stay filled? A normal party balloon will hold hydrogen just fine if the relevant timeframe is on the order of a few days. How do I know? I run an organic chemistry laboratory. My students use normal party balloons (much cheaper than balloons sold by lab supply companies, but equally effective) to set up reactions in a hydrogen atmosphere. Place the reaction flask under vacuum. Backfill the flask by connecting a balloon that was filled from a hydrogen tank. Voila... a reaction under an atmosphere of hydrogen. If everything is well sealed, then the party balloon will not leak an appreciable amount of hydrogen in a day. Mind you, these are party balloons being exposed to harsh organic solvents. In a typical home environment, they should hold up even better.

Comment: Re:Gold pressed Latinum. (Score 1) 400

by jschen (#40497919) Attached to: A Cashless, High-Value, Anonymous Currency: How?

Exactly, the technology for anonymous virtual currency already exists. But the Govt would never back such a complete anonymity. Taxation, the backbone of the govt, would be tough to enforce. Hawalas and scammers would enjoy. Now if somewhere to develop a semi-anonymous currency (like cash, with enough effort, you could probably trace it), then we probably can hope for Govt backing.

The problem with this argument is that it assumes there is but one government. Why shouldn't a small nation somewhere choose to offer financial advantages in order to lure business to its locale? (Hint: Several already do.) Why shouldn't this extend potentially to anonymous currency? If there is enough benefit to the nation (infusion of capital, prestige, whatever), then it just might happen.

Comment: Re:detectors... (Score 1) 262

by jschen (#39362857) Attached to: Instant Messaging With Neutrinos
If the matter is that dense, then it may be the size of a portable device but it still wouldn't be the mass of a portable device. Your basic assumption is that you need x amount of material to detect, and so if you pack the same amount of material tighter you should be able to detect in less space. That seems reasonable to me, but packing into less space won't reduce the mass any.

Comment: Re:Furniture (Score 1) 312

by jschen (#38426874) Attached to: Smallest space my belongings could fit (unbroken):

You measure your house in square feet....would be easier to picture that and add another dimension.

One square foot packed from floor to ceiling is about one cubic meter. One medium-sized bedroom is about 100 square feet (maybe 120, but close enough for this purpose). So if you packed your stuff from floor to ceiling with no packing materials and no waste of space, could you fit it in half of a bedroom? If so, you've got under 50 cubic meters of stuff. If not, you've got more.

Comment: Re:If only we had a space program ... (Score 1) 112

by jschen (#38080874) Attached to: Life-Bearing Lake Possible On Icy Jupiter Moon

All the elements of the periodic table are on Earth too, you know

Not necessarily... there may exist natural elements in other environments that are not found anywhere in this solar system. All we know is that for the elements we've discovered so far, there are no gaps. There may also be previously undiscovered isotopes of elements that we do know about.

I am all for space exploration, but we know about all isotopes from right here on earth. From right here on earth, we can study stable isotopes, isotopes so light that their half lives are fractionths of a second, and isotopes so heavy that their half lives are fractionths of a second. Isotopic abundances will vary by location, but the properties of the individual isotopes will be the same.

Comment: Re:@Editor (Score 1) 102

by jschen (#37880996) Attached to: Asteroid Lutetia Revealed As a Protoplanet
Historical definitions and modern definitions have little in common. The historical definition of the meter was 1/10,000,000th of the distance from the equator to the north pole along a certain longitude line. The modern definition of the meter is based on the distance a certain wavelength of light travels in a perfect vacuum in a measured amount of time. That's (indirectly, through the meter) the modern definition of an inch, too. It just happens to be a different measured amount of time. See

Comment: Re:@Editor (Score 1) 102

by jschen (#37875898) Attached to: Asteroid Lutetia Revealed As a Protoplanet

Proper science is ALWAYS based upon SI units, not imperial units.

Interesting. I just learned tonight from reading /. that I have not been doing proper science this whole time. My notebook of organic reactions is full of measurements in minutes, hours, and days. In over a decade of organic chemistry research, measurements recorded in seconds account for under 1% of my time measurements. Indeed, my raw time data usually takes the form of hours and minutes from a clock. Quick... how many seconds into the day am I at the exact moment when the second hand reaches 12 o'clock (when I usually do something if I want high precision in my timing) at 15:47? Equally importantly, why should I care?

To err is human -- to blame it on a computer is even more so.