Image by Avi Solomon, shared in the Boing Boing Flickr Pool.

Laser Umbrella

Stopping rain from falling on something with an umbrella or a tent is boring. What if you tried to stop rain with a laser that targeted and vaporized each incoming droplet before it could come within ten feet of the ground?

Zach Wheeler

Stopping rain with a laser is one of those ideas that sounds totally reasonable, but if you—

While the idea of a laser umbrella might be appealing, it—

Ok. The idea of stopping rain with a laser is a thing we're currently talking about.

It's not a very practical idea.

First, let's look at the basic energy requirements. Vaporizing a liter of water takes about 2.6 megajoules,[1]It takes more energy if the water is colder, but not much more. Heating the water up to the edge of boiling only takes a little of the 2.6 megajoules. Most of it goes into pushing it over the threshold from 100°C water to 100°C vapor. and a big rainstorm might drop half an inch of rain per hour. This is one of those places where the equation isn't complicated—you just multiply the 2.6 megajoules per liter by the rainfall rate and you get laser umbrella power requirement (watts per square meter protected). It's weird when units work out so straightforwardly: \[2.6\tfrac{\text{megajoules}}{\text{liter}}\times0.5\tfrac{\text{inches}}{\text{hour}}=9200\tfrac{\text{watts}}{\text{square meter}}\] 9 kilowatts per square meter is an order of magnitude more power than is delivered to the surface by sunlight, so your surroundings are going to heat up pretty fast. In effect, you're creating a cloud of steam around yourself, into which you're pumping more and more laser energy.

In other words, you'd be building a human-sized autoclave. Needless to say, autoclaves are not really a popular place to live.

But it gets worse! Vaporizing a droplet of water with a laser is more complicated than it sounds.[2]And to be honest, it sounds pretty complicated. There are many, many, many papers on this subject,[3]Quote from the article Explosion of a Water Droplet by Pulsed Laser Heating by J. C. Carls and J. R. Brock: "... in practice, heating a droplet to very high temperatures before substantial motion occurs ... might be difficult."

Other, out-of-context quotes from that same paper: "The droplet seems to maintain its basic shape and does not appear to be shattering", "The particles formed previously will probably be vaporized.", "By acting strangely, the equation of state is saying that all is not well", "" "Avalanche breakdown", "extremely low and sometimes negative pressures", "the most dynamic response possible", and "Notice the very high temperatures". and the general gist is that it takes a lot of energy—delivered fast—to vaporize the droplet without just splattering it apart into little droplets.

Here's a video of a droplet getting zapped by a laser pulse; you can see that it splatters the droplet, more than vaporizing it. The upshot is that cleanly vaporizing a droplet would probably take more than the already-unreasonable amounts we were considering.

Then there's the problem of targeting. In theory, this is probably solvable. Adaptive optics allow for extremely fast and precise control of beams of light. Covering an area of 100 square meters (which Zach also asked about in his full letter) would require something like 50,000 pulses per second. This is slow enough that you wouldn't run into any direct problems with relativity, but the device would—at minimum—need to be a lot more complicated than just a laser pointer on a swiveling base.

It might seem easier to forget about targeting completely and just fire lasers in random directions.[4] If you aim a laser beam in a random direction, how far will it go before it hits a drop? This is a pretty easy question to answer; it's the same as asking how far you can see in the rain, and the answer is at least several hundred meters. Unless you're trying to protect your whole neighborhood, firing powerful lasers in random directions probably won't help.

And, honestly, if you are trying to protect your whole neighborhood ...

... firing powerful lasers in random directions definitely won't help.

San Francisco photographer Kevin Twomey shot an amazing gallery of images of the inner workings of a large collection of mechanical calculating machines from the collection of Mark Glusker, stitching together multiple images to ensure that every rod, gear and linkage was vividly rendered. Read the rest

Darth Vader is showing less mercy than usual here. [via]

There are kitchen discoveries that lead to nothing but trouble. The first time I caramelized sugar, I knew I was ruined. Why would anyone want to eat drab white sugar if they could eat it cooked to a 100x as delicious toasty amber syrup? The first time I tried browned butter, I went on a butter-browning bender (cookies! breadcrumbs! crispy treats!) which, frankly, shows little sign of abating today. So, it should be no surprise that when I finally cracked the authentic pretzel-making code six months ago, I didn’t know where to stop. Everything comes up pretzel now! I’ve made pretzel scones and pretzel challahs. I’m dreaming of pretzel shortbread and popovers, pretzel bagels and grissini. I might need an intervention.

But before you all gather round my canister of food-grade lye, my latex gloves and the onion goggles I really should have more shame about owning, and sit me down for a talk about where things are going, I think we need one more pretzel thing this year, and I’d like to believe I saved the best for last.

... Read the rest of pretzel parker house rolls on smittenkitchen.com

---

© smitten kitchen 2006-2012. | permalink to pretzel parker house rolls | 196 comments to date | see more: Appetizer, Bread, Photo, Side Dish, Thanksgiving

What do you do if you sell a product on terms that legally bind your customers not to complain and they complain anyway? Pretend that the DMCA gives you the right to censor search results. Read the rest

And those things aren't true, according to an Ipsos-Mori poll that put the USA second-from-the-top in the race to see who's the most ignorant, preceded only by Italians. Read the rest

We've known for years that the FBI spied on Martin Luther King's personal life and sent him an anonymous letter in 1964 threatening to out him for his sexual indiscretions unless he killed himself in 34 days. Now we have an unredacted version of the notorious letter. Read the rest

Having lost his trademark over its overt racism, Daniel Snyder has taken the unusual step of suing the five Native American people who testified before the US Patent and Trademark Office hearing, which led to the finding that Snyder's team's name was "disparaging to Native Americans." Read the rest

The Pew Internet Project has updated its must-read 2013 work on privacy perception in the post-Snowden era with a survey of American attitudes to privacy and surveillance that shows that the number of Americans who worry about privacy is steeply rising. Read the rest

Bell and Owen Turnbull, with Nina and Shirley. The couple will have been married for 60 years in 2015. PHOTO: Jane Hilton


David Brown, 70, with Bell, a silver-laced wyandotte. PHOTO: Jane Hilton


Tommy Appleby, 88, with Pam and Rose Appleby, who lives three miles from Wood Green but visits regularly, says the project ‘saved his life’. PHOTO: Jane Hilton


Doreen Railton, 88, with Betty, an ISA warren. PHOTO: Jane Hilton


Thomas ‘Ossie’ Cresswell, with Betty Cresswell, regularly takes the chickens he cares for on ‘roadshow’ trips to schools and retirement homes.

cluckyeschickens:

"Chickens Helping The Elderly Tackle Loneliness"

A study by the University of Northumbria last September found that the male participants of HenPower all reported improved wellbeing and reduced depression and loneliness. In one dementia care home it found that since the hens had arrived violent incidents by residents were down by 50%, and the use of antipsychotic drugs was so reduced that they were no longer issued routinely.

Chickens doing wonders for senior citizens! 

Story from here.

Why not become a Patron of the Blasphemous Arts? Book shop here

State anti-abortion laws are being used to strip pregnant women of their civil rights and, in some cases, kill them. Lynn M Paltrow and Jeanne Flavin of National Advocates for Pregnant Women offer some scary examples in their piece for the New York Times. Read the rest

"A 12-year-old boy who went missing after being told off by his mother last Monday was found by police on Sunday afternoon in an IKEA store in Shanghai." Previously.

cardboardcommunist:

And for all the people out there who want to criticize like “Why do you need two bedrooms?” or “Get a better job if you want luxuries.”

1. You’re being deliberately horrible to other people. Stop.

2. If you are a parent, you probably need a couple of bedrooms so you and your children have a place to sleep. Or maybe you aren’t a parent, you’re living with a partner or a friend or a relative who is unable to work. Same thing, you need space to sleep and call your own. Not cramming everyone into one bedroom or making someone take the couch every night isn’t really a luxury.

3. The whole idea of the minimum wage when it was first implemented was that it would be enough to support a family on one person’s wages. Food, shelter, medicine, et cetera. And now, one person’s wages can’t even cover housing for the family *anywhere in the country* let alone food or medicine or anything else.

This isn’t trivial — this means tons of people are homeless and hungry and sick. This means that they labor as long and as hard (or usually longer and harder) as everyone else and they still can’t afford a warm place for their family to sleep.

I don’t think it is at all a stretch to say that people working for minimum wage are being robbed, and that that robbery has real and violent effects on laborers and their loved ones.

iwriteaboutfeminism:

What most people think causes homelessness:

• Poor money management

What actually causes homelessness:

• transphobia
• a racist criminal justice system
• the ‘war on drugs’
• health care and insurance costs
• the current federal minimum wage
• bankers being dicks
• no federal law protecting paid parental leave
• etc…

marfmellow:

If you look at the world and say “Yes, there are enough homes for people, yes, there is enough food for people, but if we give it away for free they won’t have earned it and the economy will collapse.” Then you have chosen money (a constructed medium of exchange) over living beings who only want to continue living in peace and safety.

And I have no qualms telling you, that is the wrong choice, and you have been brainwashed by this destructive, exploitative system.

By CRACKED Readers  Published: November 10th, 2014  Most of the time, we're so stuck in our monkeysphere that it's easy to forget how small we really are. But nothing like a good visual will remind you what an insignificant sack of meat you are. We asked our readers to render some size comparisons that will blow your relatively tiny socks right off your relatively tiny feet. The winner is below but first the runners-up ...

clementinemorrigan:

hiddenjumprope:

thecatsmeow90:

My lovely friends and I did a thing.

I love that this is happening.

I was fighting dress codes when I was thirteen / fourteen. That was back in 1999 and 2000. The fact that this shit is still going on is so gross. Grateful that the resistance is still happening.

micdotcom:

Women’s products cost more than men’s — and the French have had enough

It costs more to be a woman than a man.

It’s an infuriating and relatively unnoticed fact: Not only do women earn less than men, all around the world, they are essentially being “taxed” for their purchases. 

Sometimes called the “invisible,” “pink” or “woman” tax, this capitalism-induced phenomenon reflects the price difference between otherwise functionally identical products marketed to women as opposed to men.

Unlike in the United States, however, France has decided to do something about it. | Follow micdotcom

View

Serial is a podcast about a murder that happened in 1999. It's produced by This American Life and it's the best podcast series I've listened to. Read the rest

maxistentialist:

Maciej Cegłowski:

In 1952, an American attaché in Moscow was innocently fiddling with his shortwave radio when he heard the voice of the American ambassador dictating letters in the Embassy, just a few buildings away. He immediately reported the incident, but though the Americans tore the walls out of the Ambassador’s office, they weren’t able to find a listening device.

When the broadcasts kept coming, the Americans flew in two technical experts with special radio finding equipment, who meticulously examined each object in the Ambassador’s office. They finally tracked the signal to this innocuous giant wooden sculpture of the Great Seal of the United States, hanging behind the Ambassador’s desk. It had been given as a gift by the Komsomol, the Soviet version of the Boy Scouts.

Cracking it open, they found a hollow cavity and a metal object so unusual and mysterious in its design that it has gone down in history as ‘The Thing’.

‘The Thing’ had no battery, no wires, no source of power at all. It was was just a little can of metal covered on one side with foil, with a long metal whisker sticking out the side. It seemed too simple to be anything.

That night the American technician slept with ‘The Thing’ under his pillow. The next day they smuggled it out of the country for analysis.

The Americans couldn’t figure out how ‘The Thing’ worked, and had to ask the British for help. After a few weeks of fiddling, the Brits finally cracked The Thing’s secret.

That little round can was a resonant cavity. If you shone a beam of radio waves at it at a particular frequency, it would sing back to you, like a tuning fork. The metal antenna was just the right length to broadcast back one of the higher harmonics of the signal.

The resonator sat right behind a specially thinned piece of wood under the eagle’s beak. When someone in the room spoke, vibrations in the air would shake the foil, slightly deforming the cavity, which in turn made the resonant signal weaker or stronger.

As the attaché discovered, you could listen to this modulated signal on a radio just like a regular broadcast. ‘The Thing’ was a wireless, remotely powered microphone. It had been hanging on the ambassador’s wall for seven years.

Today we have a name for what ‘The Thing’ is: It’s an RFID tag, ingeniously modified to detect sound vibrations. Our world is full of these little pieces of metal and electronics that will sing back to you if you shine the right kind of radio waves on them.

But for 1952, this was heady stuff. Those poor American spooks were up against a piece of science fiction.

Today I want to talk about these moments when the future falls in our laps, with no warning or consideration about whether we’re ready to confront it.

Another amazing talk by the creator of Pinboard. I first heard Maciej speak at XOXO, he blew me away. This transcript of his Webstock talk was also amazing.

Technically outside the scope of this blog, but this was way too interesting/cool not to share.

If it fits, I sits.

Sauces that look like car polish. Windshield cleaner that looks like blue soda. Atrocious architecture. Unintentionally sexual signage. Confusing instructions. Enjoy this gallery of lousy design.