I think we were talking about the history of science funded research, before the fundies took over the popular culture with voodoo predictions of certain moral doom... at least in the scientific realm.

There were fundies back in the day that thought going to the moon would bring down the wrath of god, but they were (rightly) laughed off the podium.

Not today, alas.

Implementing the "take away your ethernet cable" punishment seems more effective than kludging together some hybrid Active Directory OpenWRT API-based webpage that's may or may not be easy to circumvent and requires specialized knowledge and lots of time to administer and check up on.

I can see it now... Parent hits "shut down now" but then runs into the bedroom to see if it's working...

At which point, the power button is only inches away.... :-P

Agreed.

This single parent is going to spend 10 hours per week troubleshooting administrative tools, when the computers he's trying to administer are like 10 feet away from him.

WTF?

Do you know how long it's been since "tin foil" actually used tin? :-)

The guy was carrying a camera, not a gun and the van that tried to rescue him was a family with kids in the back seat. In fact, there were no guns in the area.

Which part of this was a good decision?

I think, in the majority of states, both teens involved can be charged as rapists, regardless of how "consensual" it was, if they're under that magical number.

I was already assuming a 25% duty cycle (flashing aka moving the laser). I don't think you can trim it more than that without increasing the power required to make it noticeable to the naked eye. But we're still talking about a faint flashing in the sky... Not anything that demands attention.. just something subtly noticeable.

The 100mW figure was based on the brightness of the moon in the daytime sky. Surely not bright, but at least visible. Maybe 10x more would be better for people to stop and notice it...

But 1kw lasers are considered pretty high power, so we're still off by a factor of 100 or 1,000...

I dunno... Just for indonesia...

Unless you're an actor unfamiliar with the metric system who decides it's cooler to mispronounce things for artistic effect in a bad 1980s movie!

The realities of using a laser for this is just stupid.

The reality of "computer vision" for example was "wow, that's impossible with current technology, but it sure would be cool if we could figure out how".

This whole laser bit runs into issues of physics. We know how much light is lost in the atmosphere and how much power is lost in a laser ocilator and how much energy is output by the sun.

Even given 100% perfect efficiency on all of those, you're talking about 100 square kilometers of solar panels.

or... 10GW hours worth of batteries... yes. *chuckles* Unless we're talking about an antimatter reactor, that's still outside our capabilities. our best lithium polymer batteries get about 10 watts per pound. So... 1 billion pounds of batteries *chuckles*. Or 900 million tons of hydrogen fuel cells.... We would only need a few ounces of antimatter, given a perfect conversion. Or a couple of hydrogen bombs perfectly harnessed all at once.... right.

The idea of wide ranging signalling for tsunamis is interesting. The idea of using a geostationary laser is not. It's kinda funny actually.

The sun casts 1200W/m2 on objects in space. That's about 20% more than on the surface.

It's not magic sauce, it's just 20% more efficient. Whoever said that about China was an ignorant tool.

To get 25GW, you would need ten thousand square km of solar panels. Solar wind isn't a substitute for reality. :-)

To better address your question and lay a bit more clarity to it...

If a person were... say... flying... and they were up in the sky right next to the sun. Do you think a mirror in their hand would make them visible?

A mirror signaling is effective because it's done against the backdrop of the ground, which is not quite so bright as the sky, especially the sky immediately surrounding the sun.

How, dare say, do you propose to move the sattellite around when it happens to be directly in line with the sun, so as to be completely invisible.

Oye, there's so many parts of this that are just stupid.

I'm done... moving on...

good luck with your idea there, sparky.

Aside from this not working when it's cloudy, this also doesn't work when the sun is high in the sky. This is system is totally borked from 10am-6pm when the sun is up high in the sky and you won't see a flashing light against that backdrop, no matter how bright it is...

Oye...

To follow up with this, i did some research.

The full moon is quite visible during the day, but only if it's in the dark part of the sky. It has a stellar luminance of about -12 on the scale. I would figure you would need about -18 or so to have a "bright light" that would capture people's attention in broad daylight.

The approximate power required would be about 20 lux (lumens per square meter) incident on the surface, which is about 100mW per square meter.

The total coastline of places like Indonesia is hard to estimate, but it is somewhere around 60,000km. Assume 1/4 would be affected by a large non-localized tsunami and you're signaling to an area of coastline around 15,000km.

Presuming you can paint the coastline with a precise beam, say... all area within 500 meters from the water. Lets also say you're using a flashing with a 25% duty cycle (it's only on about 1/4 of the time), you're looking at 15000/8= 1800 square km or about 1.8 billion square meters "painted" at any given time.

With laser efficiency around 65% (in the best high output research lasers) and the power required around 100mW per meter incident on the surface and atmospheric losses around 40% (60% efficiency)...

((1.8b * .1) / (.65)) / .6 = 461.7 MegaWatts

Lets limit this to populated areas, say 10% of the coast. We're down to 46.2 MW.

Since the sun in space hits with about 1200W/m2, and given about 40% cell efficiency, we need about 96 square kilometers of solar cells, or about 100 4-ton steam turbines in a reactor (whether nuclear or otherwise).

Keep in mind, we're just looking at the coast of Indonesia....

Lets assume only 5% of the coast is occupied, that will reduce our power need to 23mW (only a few square KM of solar cells). But considering all the populated coastline in the Atlantic for an event like the proposed Azores landslide tsunami, lets multiply by 20.

Regardless, we're in the "entire power output of multiple massive reactors" sort of range, not the "strap it to a rocket and shoot it into orbit" sort of size.

To quote Mr Scott.

"WE SIMPLA DONT HAVE THE POWER KEPTIN"

A mirror uses the power of the sun 100w/m2 to signal over a small area (maybe a few feet).

You're talking about matching that power over a hundred thousand square miles?

Wow.

You're just not understanding the scale, I think. My flash will burn your eyes out from 5 feet away, but from the upper level of a stadium, wouldn't even make the slightest dent in the illumination. From a mile away, I don't know if it would be bright enough to get someone's attention who wasn't already staring in the right direction.

From 30,000km, it wouldn't even be close to visible.

Understanding the power of the sun, the scale of distance and the scale of the target area... Go try some experiments with lasers. They're cool, but they're not that cool. 1Kw is a lot of output for a satellite. I would wager that even a fine-beam focus from a 1kW laser on just a few hundred meters of surface would have trouble penetrating the atmosphere and being strong enough to capture someone's attention in daylight from 30,000km.

How is this something that can be replicated over.. say... 10,000 square km? You're talking terawatts of power....

As someone pointed out earlier, the island of Hawaii receives more sunlight energy than the entire output of all human power production combined... How do you even remotely close to match this?

Lighting up the daytime sky across the entirety of a major ocean coastline would cost a lot more than hundreds of millions of dollars. :-)