Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).


Comment: Questionable engineering decisions. (Score 2) 54

by mpoulton (#49500953) Attached to: Rocket Lab Unveils "Electric" Rocket Engine
Ever since their first widespread implementations in the mid 20th century, turbopumps have been powered by rocket propellants - either the same stuff they are pumping (F1 engine in the Saturn V), or a separate propellant dedicated to powering the pumps (Space Shuttle Main Engines). There are excellent reasons for this, and not many good reasons to use batteries and motors instead. Rocket propellant pumps require truly massive amounts of power to move thousands of gallons per minute of propellants at thousands of PSI pressure. The SSME turbopumps require over 70,000 horsepower per engine. Like all other rocket hardware, size and weight are extreme concerns. Power-to-weight ratio is the single most critical design goal. Rocket engines themselves burn the propellants they do specifically because those chemical combinations are the absolute best we have for producing the maximum amount of thermo-mechanical energy from the least mass, no-compromise. Using the same types of propellants to drive the turbopumps also provides the maximum achievable power to weight ratio. The SSME turbopumps produce over 100HP per pound, which is insanely high. No known electric motor technology can even reach that order of magnitude in power density, even considering only the actual motor itself! There is no legitimate contest in performance between a gas-driven turbopump and any other technology besides nuclear, and that's that. To make such a large compromise in power to weight ratio by using electric pumps is very odd. Yes, gas-driven turbopumps are really hard. They are the hardest part of building a large liquid rocket engine. But those challenges were first solved over 60 years ago, and avoiding a tough engineering exercise is no excuse for making a giant compromise in performance. The extra mass of that electric drive system could be replaced with propellant or cargo.

Comment: Murder-suicide? (Score 5, Insightful) 400

So if two listing, burning ships strap themselves together, do they float better? Or do they just sink faster? It seems to me that if your browser market-share is dropping and you're losing relevance, the best move is probably not to attach yourself to a search engine whose market share and relevance were lost years ago.

Comment: Re: Old saying (Score 4, Interesting) 249

by mpoulton (#48306777) Attached to: New Atomic Clock Reaches the Boundaries of Timekeeping
Because it would be meaningless to "compensate" for the time difference between clocks moving and accelerating differently. Time literally moves at different rates in different reference frames. The clocks are correct; the problem is that the concept of similtaneity is fundamentally flawed.

Comment: Re:Things once thought impossible... (Score 2) 350

by mpoulton (#48173217) Attached to: The Physics of Why Cold Fusion Isn't Real

1. Powered Flight 2. Bending Light 3. Traveling Greater than 300mph 4. Transparent Aluminum 5. Artificial Diamonds

All of these "Feats" of human ingenuity were once thought to be impossible by the physics standards of the day.

Physics and our understanding of it, continues to evolve every moment we live.

To say the words "It Cannot Be Done" after seeing all we have done already... Is kind of foolish.

We will learn how to accomplish this feat, or one very similar that accomplishes the same goal, Eventually...

That, is the power of Consciousness My Friends.

All hail the thinking, reasoning, Problem Solving, Human Consciousness!

Hold up there, turbo. Transparent aluminum? Surely you're not serious. And don't post a link to something about aluminum oxide or other ceramics.

Comment: "Smart earrings" or "smart necklaces" too? (Score 1) 381

by mpoulton (#47439669) Attached to: Slashdot Asks: Do You Want a Smart Watch?
No, I do not want a "smart watch" any more than I want any other "smart" jewelry. Purely functional timepieces are obsolete. If all you want is to know the time, your phone already solves that problem for you - hence the decrease in percentage of people wearing watches. A modern wristwatch is a piece of jewelry where its functionality (and the means of achieving it) are part of the beauty. "Smart watches" have enhanced functionality, but universally at the expense of beauty. The aesthetics are terrible, thus defeating the primary purpose of a watch these days.

Comment: Re:The actual Guides (Score 4, Informative) 286

by mpoulton (#47335187) Attached to: What To Do If Police Try To Search Your Phone Without a Warrant

Since the summary links you to a stupid news article and not the guides themselves, here is the ACLU Guide and EFF Guides here.

The EFF guide you linked has not been updated yet to reflect the Riley decision. Some of those answers need to be changed because they are incorrect now. The ACLU "Know Your Rights" manual does not appear to have been updated either, but it simply doesn't address the issue of cell phone searches incident to arrest at all.

Comment: Who is being taxed, exactly? (Score 1) 322

by mpoulton (#47189057) Attached to: Fixing China's Greenhouse Gas Emissions For Them
Soooooo.... we tax ourselves to make China change? Because that's what's being proposed. Tariffs are passed straight through to the buyers of the products. We we're raising prices on imported goods, to change the behavior of the manufacturers, who will still take in the same revenue. As long as domestic manufacturing remains more expensive than the imports plus tariffs, we will still be buying the imported goods, just paying more for them and funneling the extra money back to the federal government.

Comment: Re:Gun nuts (Score 1) 1374

by mpoulton (#46892067) Attached to: "Smart" Gun Seller Gets the Wrong Kind of Online Attention

A weapon intended for target practice, sport, or self defense has absolutely no need for a flash suppressor. This type of "feature" is intended for covert use of the weapon, which I'd argue falls under what most would categorize as an assault weapon.

Aside from your apparent lack of knowledge about what different types of weapons and accessories are used for, your general premise is mostly correct. Flash suppressors are more useful in actual combat than in most other situations. That type of use is exactly what the Second Amendment explicitly protects. Target practice, sport, hunting, and defense from crime are merely secondary byproducts of having a "well regulated"* militia.

* "regulated" meant "equipped" at the time it was written - see DC v. Heller for a detailed analysis.

Comment: Silicone. Silicone. Silicone. (Score 5, Interesting) 62

by mpoulton (#46845683) Attached to: 3D Printer Lays Down Functioning Circuitry Alongside Thermoplastic
"the syringe-like printer head has used silver-filled silicon to create circuitry"

No, it didn't. That's SILICONE not silicon. I mean, come on. This is a technical article on a technical website. Can't we at least get basic chemistry right? Do you fill your car's gas tank with carbon? If there's one damn place on the internet where people can be expected to know enough about science to see the difference between a hard, shiny metallic element and a class of clear rubbery compounds that happen to contain that element, it should be here.

Comment: Now it's the grid engineers' problem to solve... (Score 5, Informative) 227

by mpoulton (#46684533) Attached to: Nanodot-Based Smartphone Battery Recharges In 30 Seconds
A Tesla S has an 85kWh battery. To charge that in 30 seconds requires 10,200,000 watts of power - approximately the full electrical service to a decent size skyscraper. That's 42,500 amps at 240V, the full maximum power available to over 212 modern homes and a totally impractical amount of current to handle with any reasonable electrical equipment. So while fast-charging batteries are great and a necessary step forward in technology, the universal adoption of electric cars will require not just upgrading our infrastructure, but a complete rethinking and redevelopment of the electrical grid using not-yet-imagined technologies.

"If truth is beauty, how come no one has their hair done in the library?" -- Lily Tomlin