I have a problem with the physics here. You see, +Ethan Siegel has worked out a good mechanism for the Death Star to be able to blow up Alderaan in the roughly three seconds that it took for the planet to explode: namely, a charge of roughly 1.24 trillion tons (1.24*10^15kg) of antihydrogen. You could presumably manufacture this elsewhere, in a place where you had access to the complete energy resources of a star with which to do so (hey, if you can build a space station that can pass for a moon, you can build a Dyson Sphere and harvest a star’s energy), store it aboard your Death Star, and ship it to Alderaan in time to make a demonstration of the power of the Empire.However, an antimatter weapon like this would suffer from the same technical challenge that makes building an atomic bomb difficult: the moment the matter and antimatter touch, they will start to explode (just like the moment you assemble a critical mass of Uranium or Plutonium), and the explosion will then propel the rest of the material in opposite directions at fairly high speed. In fact, if the Death Star were simply chucking antimatter at Alderaan, it would probably strike the surface, explode dramatically, and catapult most of the antimatter right back at the Death Star, which would be considerably less effective political theater.If you want an anti-planet weapon to work properly, you have to get the antimatter deep inside the planet — as close to the center as possible — before it starts to react. How can we do this?Your first guess might be to put it inside a big artillery shell, and fire it really fast. Unfortunately, that turns out not to work. Isaac Newton himself was the one who explained why: if a projectile is being stopped by digging into the earth, only the dirt directly in front of the projectile can contribute to stopping it. That dirt is going to be moved at the same speed as the projectile (since that’s what’s pushing it), and so once an equal mass of dirt has been pushed by it, it will stop. (You can read more about this at http://en.wikipedia.org/wiki/Impact_depth) A bit of algebra shows that the actual depth is equal to the length of the projectile times the ratio of the density of the projectile to the density of the thing it’s trying to penetrate. (This is why armor-penetrating rounds are made of dense materials such as depleted Uranium) Unfortunately, antimatter doesn’t get any denser than regular matter, so you simply couldn’t burrow all that deep.A second approach would be to fire the round very, very, fast. This is basically how gun-based nuclear weapons work: you make the collision quick enough that, by the time the reaction starts, the critical mass is already fully assembled. Really, so long as you get the entire antimatter slug underground before it goes off, the explosion will basically work; you’ll probably need more antimatter to account for the fact that the explosion isn’t properly centered in the planet, but that’s workable. Unfortunately, antimatter reactions start just as fast as nuclear reactions, so you would have to get the entire slug underground in a microsecond or so for this to work.Let’s say that our enlarged slug weighed five trillion tons. (5*10^15kg) We don’t know the exact density of metallic (anti)hydrogen, but it’s probably somewhere around 0.5g/cm^3, since very light metals aren’t dense. A very flat slug would have weird aerodynamics, so we could imagine making it spherical, giving it a diameter of about 57km. To get that underground in a microsecond would give it a momentum of 2.8*10^16 kg-m/s. The recoil of that would propel our own Moon backwards at about 3,800m/s (8,700mph), and the Death Star, being smaller, would have been shot backwards even faster. Clearly, this isn’t going to work.A better approach may be to look at how lightning bolts work. In lightning strikes, a small “leader” bolt works its way from the cloud to the ground, leaving in its path an arc of air that has been ionized and is therefore highly electrically conductive. Once that conductive path connects cloud to surface, the main bolt can follow through easily. (See also https://what-if.xkcd.com/16/) There have been attempts to build plasma rifles on similar principles. (Seriously) Plasma is a gas which has been further energized so that the electrons start getting ripped off the atoms; it’s electrically charged and quite energetic, so it can be an effective thing to throw at someone you don’t like. Unfortunately, it will hit the air in front of you just as effectively as the person on the other end of it, so actually shooting it at someone is difficult. The proposed ideas around this therefore begin by firing a powerful laser to blow out an open cavity in the air, and firing lumps of plasma through the resulting short-lived vacuum.A similar approach could power the Death Star: a (very big) laser could burn a short-lived, narrow hole through Alderaan, and the antimatter would be fired into the resulting vacuum. Then the hole is allowed to collapse, and the antimatter is conveniently at the center of the planet. The challenge would be that for this to work, it would have to be a through hole: if you burned a hole that didn’t go all the way to the other end of the planet, the most you could do is make the matter in front of the beam evaporate, and you would still have a bunch of boiling planet between you and the center. No help for our antimatter charge!So our solution has to be:(1) Use the giant laser of the Death Star to burn a thin hole all the way through Alderaan.(2) Keep firing that laser until it clears out the entire path into a vacuum.(3) Fire the antimatter pellet in along that path. (The laser can be used to propel the antimatter down the pipe, as well! Simply put a material on the back of the antimatter housing which will get evaporated by the beam, and the equal and opposite force will push it fast. Believe it or not, this is an actual proposed method of powering spacecraft!)(4) Once it’s at the middle of the planet, turn the power off. The planet quickly collapses around the hole, the antimatter reacts with the matter, and — having nowhere else to escape to — continues to react until all of the antimatter has gone off.(5) There is an earth-shattering Kaboom. (http://youtu.be/KNEBLXgWhtM?t=23s)So now we know what the bright green beam of the Death Star was, and those little bulbous pulses which flew along it later.Mystery solved!h/t to +Jennifer Ouellette for linking to the post, and to +Ethan Siegel for a very enjoyable calculation to run while I procrastinate wait for a compute job to finish. (http://xkcd.com/303/)http://click-to-read-mo.re/p/9sSn/530cf59c
I have a problem with the physics here. You see, +Ethan Siegel has worked out a good mechanism for the Death Star to be able to blow up Alderaan in the roughly three seconds that it took for the planet to explode: namely, a charge of roughly 1.24 trillion tons (1.24*10^15kg) of antihydrogen. You could presumably manufacture this elsewhere, in a place where you had access to the complete energy resources of a star with which to do so (hey, if you can build a space station that can pass for a moon, you can build a Dyson Sphere and harvest a star’s energy), store it aboard your Death Star, and ship it to Alderaan in time to make a demonstration of the power of the Empire.

However, an antimatter weapon like this would suffer from the same technical challenge that makes building an atomic bomb difficult: the moment the matter and antimatter touch, they will start to explode (just like the moment you assemble a critical mass of Uranium or Plutonium), and the explosion will then propel the rest of the material in opposite directions at fairly high speed. In fact, if the Death Star were simply chucking antimatter at Alderaan, it would probably strike the surface, explode dramatically, and catapult most of the antimatter right back at the Death Star, which would be considerably less effective political theater.

If you want an anti-planet weapon to work properly, you have to get the antimatter deep inside the planet — as close to the center as possible — before it starts to react. How can we do this?

Your first guess might be to put it inside a big artillery shell, and fire it really fast. Unfortunately, that turns out not to work. Isaac Newton himself was the one who explained why: if a projectile is being stopped by digging into the earth, only the dirt directly in front of the projectile can contribute to stopping it. That dirt is going to be moved at the same speed as the projectile (since that’s what’s pushing it), and so once an equal mass of dirt has been pushed by it, it will stop. (You can read more about this at http://en.wikipedia.org/wiki/Impact_depth) A bit of algebra shows that the actual depth is equal to the length of the projectile times the ratio of the density of the projectile to the density of the thing it’s trying to penetrate. (This is why armor-penetrating rounds are made of dense materials such as depleted Uranium) Unfortunately, antimatter doesn’t get any denser than regular matter, so you simply couldn’t burrow all that deep.

A second approach would be to fire the round very, very, fast. This is basically how gun-based nuclear weapons work: you make the collision quick enough that, by the time the reaction starts, the critical mass is already fully assembled. Really, so long as you get the entire antimatter slug underground before it goes off, the explosion will basically work; you’ll probably need more antimatter to account for the fact that the explosion isn’t properly centered in the planet, but that’s workable. Unfortunately, antimatter reactions start just as fast as nuclear reactions, so you would have to get the entire slug underground in a microsecond or so for this to work.

Let’s say that our enlarged slug weighed five trillion tons. (5*10^15kg) We don’t know the exact density of metallic (anti)hydrogen, but it’s probably somewhere around 0.5g/cm^3, since very light metals aren’t dense. A very flat slug would have weird aerodynamics, so we could imagine making it spherical, giving it a diameter of about 57km. To get that underground in a microsecond would give it a momentum of 2.8*10^16 kg-m/s. The recoil of that would propel our own Moon backwards at about 3,800m/s (8,700mph), and the Death Star, being smaller, would have been shot backwards even faster. Clearly, this isn’t going to work.

A better approach may be to look at how lightning bolts work. In lightning strikes, a small “leader” bolt works its way from the cloud to the ground, leaving in its path an arc of air that has been ionized and is therefore highly electrically conductive. Once that conductive path connects cloud to surface, the main bolt can follow through easily. (See also https://what-if.xkcd.com/16/

There have been attempts to build plasma rifles on similar principles. (Seriously) Plasma is a gas which has been further energized so that the electrons start getting ripped off the atoms; it’s electrically charged and quite energetic, so it can be an effective thing to throw at someone you don’t like. Unfortunately, it will hit the air in front of you just as effectively as the person on the other end of it, so actually shooting it at someone is difficult. The proposed ideas around this therefore begin by firing a powerful laser to blow out an open cavity in the air, and firing lumps of plasma through the resulting short-lived vacuum.

A similar approach could power the Death Star: a (very big) laser could burn a short-lived, narrow hole through Alderaan, and the antimatter would be fired into the resulting vacuum. Then the hole is allowed to collapse, and the antimatter is conveniently at the center of the planet. 

The challenge would be that for this to work, it would have to be a through hole: if you burned a hole that didn’t go all the way to the other end of the planet, the most you could do is make the matter in front of the beam evaporate, and you would still have a bunch of boiling planet between you and the center. No help for our antimatter charge!

So our solution has to be:

(1) Use the giant laser of the Death Star to burn a thin hole all the way through Alderaan.

(2) Keep firing that laser until it clears out the entire path into a vacuum.

(3) Fire the antimatter pellet in along that path. (The laser can be used to propel the antimatter down the pipe, as well! Simply put a material on the back of the antimatter housing which will get evaporated by the beam, and the equal and opposite force will push it fast. Believe it or not, this is an actual proposed method of powering spacecraft!)

(4) Once it’s at the middle of the planet, turn the power off. The planet quickly collapses around the hole, the antimatter reacts with the matter, and — having nowhere else to escape to — continues to react until all of the antimatter has gone off.

(5) There is an earth-shattering Kaboom. (http://youtu.be/KNEBLXgWhtM?t=23s)

So now we know what the bright green beam of the Death Star was, and those little bulbous pulses which flew along it later.

Mystery solved!

h/t to +Jennifer Ouellette for linking to the post, and to +Ethan Siegel for a very enjoyable calculation to run while I procrastinate wait for a compute job to finish. (http://xkcd.com/303/)

http://click-to-read-mo.re/p/9sSn/530cf59c
This is smart marketing. But what many will not realize is that Apple is still gathering all this data. They’re storing your intimate pictures and videos, tracking your precise location, keeping a history of everything you search, browse, and bookmark. If required (or strong armed) by a government, they’ll give that data up. They just don’t use it to help serve up more relevant, valuable content (and yes, ads).Google does all of the above but puts that data to use. I’m not sure which approach I like more; Google’s services are immensely useful and I’d rather see relevant ads than irrelevant ones. Apple has a strongly worded argument here, but I don’t know how well it stands up.▼ Reshared Post From Koushik Dutta ▼Damn, Apple is pulling no punches on their marketing message around privacy and advertising.http://click-to-read-mo.re/p/9sSm/530cf59c

This is smart marketing. But what many will not realize is that Apple is still gathering all this data. They’re storing your intimate pictures and videos, tracking your precise location, keeping a history of everything you search, browse, and bookmark. If required (or strong armed) by a government, they’ll give that data up. They just don’t use it to help serve up more relevant, valuable content (and yes, ads).

Google does all of the above but puts that data to use. I’m not sure which approach I like more; Google’s services are immensely useful and I’d rather see relevant ads than irrelevant ones. Apple has a strongly worded argument here, but I don’t know how well it stands up.

▼ Reshared Post From Koushik Dutta ▼

Damn, Apple is pulling no punches on their marketing message around privacy and advertising.

http://click-to-read-mo.re/p/9sSm/530cf59c

Linux and Linux-based software has changed immensely in the past few years. Yet it still holds this stigma of difficulty, nerdiness, or obscurity.This is part of the reason +elementary doesn’t blatantly call itself “Linux.” The Linux kernel is a part of its stack, sure. But so are GTK+, DBus, GStreamer, GNU, WebKit, Mutter, and on and on. Android doesn’t advertise itself as Linux even though it utilizes the Linux kernel. That low level part of the operating system no longer determines the user experience that is happening on top, and lately there are some pretty awesome things happening with those experiences.▼ Reshared Post From Wantoo Sevin ▼"But the reality is that most Linux newbies aren’t coming from a blank slate; they’re coming from Windows or Mac. If a user comes to Linux expecting it to behave like another operating system, yes, it will be difficult and frustrating."http://www.makeuseof.com/tag/5-lies-linux-haters-like-tell/http://click-to-read-mo.re/p/9jav/530cf59c

Linux and Linux-based software has changed immensely in the past few years. Yet it still holds this stigma of difficulty, nerdiness, or obscurity.

This is part of the reason +elementary doesn’t blatantly call itself “Linux.” The Linux kernel is a part of its stack, sure. But so are GTK+, DBus, GStreamer, GNU, WebKit, Mutter, and on and on. Android doesn’t advertise itself as Linux even though it utilizes the Linux kernel.

That low level part of the operating system no longer determines the user experience that is happening on top, and lately there are some pretty awesome things happening with those experiences.

▼ Reshared Post From Wantoo Sevin ▼

"But the reality is that most Linux newbies aren’t coming from a blank slate; they’re coming from Windows or Mac. If a user comes to Linux expecting it to behave like another operating system, yes, it will be difficult and frustrating."

http://www.makeuseof.com/tag/5-lies-linux-haters-like-tell/

http://click-to-read-mo.re/p/9jav/530cf59c

The heavy use of black makes me wonder if Apple is using an OLED (or similar) display where the darker pixels use less energy and black pixels don’t use any. It’d make a lot of sense on a watch to maximize battery life. And since Apple has full control over the software, they can make the UI black-heavy whereas I believe Android Wear devices would have to wait for Google to add a battery saver/night mode feature to the software.I’ve just noticed the Apple Watch UI is really dark.▼ Reshared Post From Ron Amadeo ▼Apple Watch versus Android Wear: fight!I think if, years ago, you showed someone this gallery they would think the Apple Watch was made by Google and that Android Wear was an Apple product.Google built a light, airy, voice command and notification-powered appliance, while Apple is making a dense, more powerful, mini-smartphone with an all-black motif. It’s like they swapped places.I’m not sure which is right, but I definitely want my smartwatch to do more right now.http://click-to-read-mo.re/p/9iXd/530cf59c

The heavy use of black makes me wonder if Apple is using an OLED (or similar) display where the darker pixels use less energy and black pixels don’t use any. It’d make a lot of sense on a watch to maximize battery life.

And since Apple has full control over the software, they can make the UI black-heavy whereas I believe Android Wear devices would have to wait for Google to add a battery saver/night mode feature to the software.

I’ve just noticed the Apple Watch UI is really dark.

▼ Reshared Post From Ron Amadeo ▼

Apple Watch versus Android Wear: fight!
I think if, years ago, you showed someone this gallery they would think the Apple Watch was made by Google and that Android Wear was an Apple product.

Google built a light, airy, voice command and notification-powered appliance, while Apple is making a dense, more powerful, mini-smartphone with an all-black motif. It’s like they swapped places.

I’m not sure which is right, but I definitely want my smartwatch to do more right now.

http://click-to-read-mo.re/p/9iXd/530cf59c

Let’s do this. Who’s with us?

▼ Reshared Post From Daniel Foré ▼

Back in the day, there was this great app for windows called “RPG Maker”. As a game engine, it wasn’t really that powerful. It was just in 2D and there were a lot of restrictions. But its main strength was that it was stupidly easy to use. A non-programmer could pretty easily generate a decent quality game. I played through quite a few of them. One of my favorites was an adaptation of a book. Another was built around the concept of only using the default characters and assets that came in the “run time package”.

I think we need another “RPG Maker”. A stupidly simple game engine that enables indie game designers to get their ideas out there. But I have an idea about how to really make it awesome:

Let’s start a “Game Studio”. And let’s run it like Blender: every year the studio puts out a concept that’s intent is to create/improve features for the engine. But actually, instead of putting out a new concept game every year let’s make one game: an action/adventure MMORPG.

Why would we make an MMO? Mainly because it’s probably one of the hardest types of games to make, with all the challenges of any other genre combined, plus networking. But also because we can probably make some money off an MMO by doing some kind of freemium/subscription model and invest that into the incredibly talented people it takes to build a game engine/game.

The goal being to create a game engine that enables relative non-developer game designers to create beautiful, immersive gaming experiences with a Linux-first mentality. Let’s not just be another platform for game designers. Let’s be the best platform for game designers.

http://click-to-read-mo.re/p/9iSC/530cf59c

I noticed this right away; I have the Dualshock 4 brightness set to the default bright, but Destiny keeps it pretty dim unless they’re using it. When I’m playing in my dark family room and my legs, coffee table, and opposite wall glow red, it’s time to duck for cover. :)I also really like that they light it up for the flashlight. It’s a feeling of immersion I didn’t expect.▼ Reshared Post From Russell Holly ▼When you take critical damage in Destiny, the DualShock 4 lets everyone else in the room know it. I say everyone else, because you are way too busy to look down and notice it.Kinda cool, kinda useless.http://click-to-read-mo.re/p/9hyp/530cf59c

I noticed this right away; I have the Dualshock 4 brightness set to the default bright, but Destiny keeps it pretty dim unless they’re using it. When I’m playing in my dark family room and my legs, coffee table, and opposite wall glow red, it’s time to duck for cover. :)

I also really like that they light it up for the flashlight. It’s a feeling of immersion I didn’t expect.

▼ Reshared Post From Russell Holly ▼

When you take critical damage in Destiny, the DualShock 4 lets everyone else in the room know it. I say everyone else, because you are way too busy to look down and notice it.

Kinda cool, kinda useless.

http://click-to-read-mo.re/p/9hyp/530cf59c