Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Comment Re:11 rear enders (Score 1) 549 549

I was driving in some suddenly icy conditions once, and had just crested a large hill that went steeply downward after the crest. ABS, by some miracle of technology brought my car to a stop before the bottom, saving me from sliding right into a busy de-iced street with 45mph traffic flowing.
It pains me every time I hear uber-drivers talking about how they hate ABS.

Comment Re: Webassembly means... (Score 1) 175 175

I concur emphatically.
My first forays into machine code (manually constructed with a book and poked) was on a Z80... And it really was an amazingly fun experience.
These days, dealing with assembly in modern ARM and MIPS processors, while so much more capable, and having features that make writing assembly ridiculously powerful, I do miss the utter simplicity of that Z80- so simple a kid was able to pick it up.
It really was great fun.

Comment Re:Effect of nukes on NEOs (Score 1) 272 272

No, because those millions of small pieces release the same amount of energy into the Earth system, just now into the atmosphere now rather than the planet surface

You start with an incontrovertible claim,

Rather than ejecting material, earthquakes, tsunamis, you flash fry the hemisphere

And you use it to justify pure poppycock?
The atmosphere is big. The earth- it's also really goddamn big. The energy required to raise a hemisphere's atmospheric temperature enough to "fry" us is so goddamn big that there's no point in worrying about it. If something the size of Texas is about to hit us, we're just fucked.

The beast that (I guess contentiously, now?) knocked out the dinosaurs, spread across an entire hemisphere would yield about 193MW/m^2, to dissipate through a 100km column, giving us... 1.9kW/m^3 of dissipation, assuming impossibly worst case scenario (instantaneous thermal conversion across entire air volume)... which is quite survivable.

Realistically, the dissipation will be far better distributed over time and area (a lot of impactors will take long paths through the atmosphere, being not direct hits, better improving their dissipation at high altitudes)

It's not a... "good" thing, for sure... But it's not the total annihilation of a hemisphere.

Comment Re:Effect of nukes on NEOs (Score 1) 272 272

What sort of nuclear engine are you envisioning that would match the thrust of bombs boiling off the asteroid's surface in a big plasma wave?

I'm pretty confident that absorbing half of the energy output of a significantly sized fusion explosive (say, dozens of megatons) is going to do a lot more for you than just the ablative propulsion effects of the vaporized surface.

You're still going to send a pressure wave through that rock that is going to be a very formidable force in comparison to the very weak gravity holding it together.
This obviously isn't too helpful for a world-ending impactor (hundreds of miles+), but I'm guessing highly dangerous ones of that size and smaller could be reduced to buck shot.

One NASA-funded plan involved hitting it with an impactor first and then having the nuclear explosive follow it in. Even more energy absorption, and even more fertile ground for a very serious pressure wave.

The 5MT device detonated 1.8km deep on Amchitka lifted the ground at the surface by 20 feet. Imagine what that'd be like without 9.8m/s^2 of force pulling it back together, and without the weight of nearly 2km of rock to fight the expansion.

Comment Re: Effect of nukes on NEOs (Score 1) 272 272

Some of them will go in the opposite direction

Unlikely. This isn't a stationary object, and the velocity of it is almost stupid. Sure you'll slow a lot of pieces down a lot, but I sincerely doubt you'll reverse their trajectory.

That's assuming that the nuke actually blows it up. Nukes are FAR less effective in space because there's no atmosphere for the thermal energy to create a big shockwave, and there's no solid ground beneath it to amplify the intended direction of said shockwave.

That's ok, rock absorbs high energy photons and neutrons even better than air. The shockwave of a nuke causes the serious damage away from the fireball, but I assure you the people within the area of atmospheric ignition due to high-energy radiation couldn't give two squirts of piss about the pressure of the atmosphere there. Definitely detonate close to the bolide.

IMO if you want to blow up an NEO, you'll probably want some kind of kinetic weapon akin to a giant bullet, maybe a space born railgun or something.

You could be right... But I doubt it. Someone would have to do the math to see what portion of the energy output of a large hydrogen bomb would hit the object, how much the object would absorb, and how it would react to the incidental heating. (my guess is very traumatic explosion of the object itself)

Still though, nudging is probably a better approach.

I think we all agree here

Comment Re:Effect of nukes on NEOs (Score 1) 272 272

Come on, now.
Your second sentence is certainly correct, however, your first couldn't be more wrong in its conclusion.

Which would you rather be hit with? A ~150J .22LR round, or a ~320J baseball?
Contact area of the kinetic energy matters. The atmosphere is going to do a great job of absorbing nearly ALL of the kinetic energy of a large impactor, if you can reduce it to small enough rubble, while it isn't going to do shit against a big dense bolide with a minimal contact area.

I'll take atmospheric buck shot over a .50 cal any day.

Comment Re:Icehouse Earth (Score 1) 637 637

Give that a little thought.

Done. Still stands. Your argument is vindicated because you argued with someone who disagreed with you, and used information from their side against them. They lost, but you sure as hell didn't win.

By that bizarre logic the earth itself is an infection.

That's so non sequitur I'm unsure how to respond to it. An infection upon what? The solar system? For the destabilizing influence it has upon it? The Universe? Help me.

Given that the earth has never had a stable climate, your notions are entirely alien to nature itself.

This is nonsense. The glacial/interglacial oscillation of the current ice age is quite stable. The fact that catastrophes have occurred to destabilize it on 2-3 occasions in the last million or so years does not unstable make.

No, you refer to watermelons, the leftist interpretation of environmentalism - which has very firm roots among the monied classes of the 19th century, to say nothing of conservationism whose earliest manifestations can be tracked back a full thousand years earlier. Much like social welfare systems and every other ostensible social good Marxists have latched onto since Karl hoisted the first of many, many alcoholic beverages, this stuff has been around for a very long time. You'd think you people would learn, I mean Russia has wound up somewhere to the right of Genghis Khan and China's busily returning to its imperial roots, complete with caste system. What you do is create reactions which eventually end up consuming any gains you might have made, a process which will inevitably end up being replicated even in the enlightened and much reviled (by the left) west. Leftists believe me to be a conservative reationary, conservatives call me a progressive swine, I'm quite content to watch all of you idiots get hoisted by your own petards.

It's funny that you make it political. Your colors are showing :)
I'm no leftist. I would classify myself as socially liberal, for sure, however, I'm as capitalist as the next guy.

Both leftists and conservatives should call you what you are- A person who thinks only in partisanship. The very problems of the world for you can't be seen as anything but right-wing or left-wing.
I don't care who Big Oil votes for today. Their loyalty lies only in the price of their commodity. They have no ideology beyond that. But they and their blind supporters (which admittedly do tend to be conservative, however, that's simply because that's who the conservative football team is playing for right now. It could change next election.) are the opposing side I referred to.

In these matters the only certainty is that there is nothing certain. -- Pliny the Elder