Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

We are sorry to see you leave - Beta is different and we value the time you took to try it out. Before you decide to go, please take a look at some value-adds for Beta and learn more about it. Thank you for reading Slashdot, and for making the site better!

Comments

top

Judge Says You Can Warn Others About Speed Traps

jschen Many speed traps are published (457 comments)

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: http://www.kcci.com/news/traff... Amusingly, one police department near Des Moines publishes the plans on their Facebook page.

about 10 months ago
top

Tesla To Build Its Own Battery-Swap Stations

jschen short-term battery loan (377 comments)

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.

about a year and a half ago
top

Scientists Speak Out Against Wasting Helium In Balloons

jschen Re:How to decide the fate of helium (589 comments)

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.

about 2 years ago
top

35 Years Later, Voyager 1 Is Heading For the Stars

jschen Re:2020? (226 comments)

The power of the plutonium RTGs continually declining is one issue, as already noted. Another issue is the finite amount of hydrazine on board for what little maneuvering may need to be done. See the last paragraph of this page and this article.

more than 2 years ago
top

A Cashless, High-Value, Anonymous Currency: How?

jschen Re:Gold pressed Latinum. (400 comments)

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.

more than 2 years ago
top

MIT Solar Towers Beat Solar Panels By Up To 20x

jschen Re:But much harder to set up (159 comments)

You don't need to see the sun to track it. Its location is predictable, so you only need to know your current location (easily determined by GPS at installation) and the current date and time.

more than 2 years ago
top

Instant Messaging With Neutrinos

jschen Re:detectors... (262 comments)

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.

more than 2 years ago
top

Fake IPad 2s Made of Clay Sold At Canadian Stores

jschen Re:Returns (265 comments)

Furthermore, the store acknowledges that returned iPads appears to be the way the clay fakes got there in the first place. It says so right in the summary.

more than 2 years ago
top

Smallest space my belongings could fit (unbroken):

jschen Re:You've illustrated the problem perfectly (312 comments)

Oops... messed up the number of dimensions in my estimation. Frankly, that type of error in mental arithmetic could happen with any unit of measure, metric or not.

more than 2 years ago
top

Smallest space my belongings could fit (unbroken):

jschen Re:Furniture (312 comments)

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.

more than 2 years ago
top

Life-Bearing Lake Possible On Icy Jupiter Moon

jschen Re:If only we had a space program ... (112 comments)

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.

about 3 years ago
top

Asteroid Lutetia Revealed As a Protoplanet

jschen Re:@Editor (102 comments)

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 http://www.npl.co.uk/reference/faqs/on-what-basis-is-one-inch-exactly-equal-to-25.4-mm-has-the-imperial-inch-been-adjusted-to-give-this-exact-fit-and-if-so-when-(faq-length)

about 3 years ago
top

Asteroid Lutetia Revealed As a Protoplanet

jschen Re:@Editor (102 comments)

An inch is defined as exactly 2.54 centimeters. I don't know how much more based on SI units it could be. It's not really any different from how we define minutes, hours, days, and years. Those aren't all factors of 10, either.

about 3 years ago
top

Asteroid Lutetia Revealed As a Protoplanet

jschen Re:@Editor (102 comments)

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?

about 3 years ago
top

Cutting Open a Heatsink Heatpipe To See Inside

jschen Re:Excellent idea for overclocking (132 comments)

That's silly. We all know that heat rises. It's true that you want to cut a hole in the floor, but it's to get the cold air. (Don't worry... that heat engine will still work.) You need another hole in the ceiling for the heat to escape. Straddle the hole and hold your laptop right there, and you'll get the best cooling. If you don't believe me, just try it!

about 3 years ago
top

Jaguar Recalls 18,000 Cars Over Major Software Fault

jschen Re:My car has a fail-safe device... (356 comments)

Left foot on clutch. Left side of right foot on brake pedal. Right side of right foot partial throttle. Let off clutch pedal far enough for the clutch to bite and transmit enough power to have the car straining forward just a bit. Roll right foot gradually off the brakes and onto the gas while continuing to let off the clutch. With just a little practice, you can pull this off with _zero_ backward rolling. You can do it quickly to get a fast start, or slowly to get a nice slow roll.

about 3 years ago
top

A Silicon Valley School That Doesn't Use Computers

jschen Re:Take a good thing too far... (333 comments)

I think people who are sending their children to this school will be able to teach their children the necessary computer skills just fine without the help of the school.

more than 2 years ago
top

A Silicon Valley School That Doesn't Use Computers

jschen Re:Feedback (333 comments)

I also have yet to meet a piece of paper that gives immediate feedback. However, I have met teachers who can give better targeted and more useful feedback than any computer program. Learning tools are great, but perhaps a bit more emphasis should be given to inspiring and training more good teachers.

more than 2 years ago
top

Can the Hottest Peppers In the World Kill You?

jschen Re:Capsacin (337 comments)

But "tiny cuts would get infected, and spread," the reason that you're telling me that a high (absurd, but theoretical) dose of capsacin would lead to mass tissue death, is exactly the outcome the immune system fights against! That part wouldn't be affected at all by turning off nerve receptors. Nor would the clotting process. So how exactly does turning off a receptor in a nerve affect the body's ability to heal? Numbing a cut on the outside of the body certainly doesn't affect the body's ability to heal on the outside. The digestive tract is topologically on the outside, so I fail to see the difference. I'm not trying to be argumentative, but I'm genuinely curious since what you're telling me strikes me as being extremely counterintuitive.

more than 3 years ago

Submissions

jschen hasn't submitted any stories.

Journals

jschen has no journal entries.

Slashdot Login

Need an Account?

Forgot your password?