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Comment Re:Concentrations (Score -1) 216

Um, just a minute - let's insert some math here:

0.18 trillion = 180 billion equivalent units
400 million *7000 = 2800 billion equivalent units

So, if the article summary is correct over 90% of any anthro warming is not due to CO2, proving the skeptics correct.

I strongly doubt that the article is correct.

Comment Re:Well it is far, far away (Score 1) 110

Or, possibly this is an alien factory planet...

To make more energy available, they take all of a solar system's rocky mass and put it into an orbit skimming close to the central star. That way the metals can be easily separated out, and worked. Since heat engines become more efficient at higher temperatures (especially when you have to radiate waste heat to space), much more energy is available for engineering processes.

This planet isn't "a complete mystery" - it is final, clinching proof of extraterrestrial intelligent life!

Or not...

Comment Re:Wait, what? (Score 1) 134

and the vast majority are complete and utter failures.

I would add to this, though - they may have failed, but they likely learned something that will permanently increase their value to society. And, because of that, permanently increase their income.

I strongly recommend that all college students try to start a business. Yes, you will likely fail - but you will be exposed to thing that will change your perspective forever.

Comment Re:Retire at 20 (Score 4, Insightful) 358

Actually, I pretty much disagree entirely with that analysis...

The question is not "sell low" or "sell high" - you do not know the future, so that fact that it went up is not available to you before the decision. The question is are you getting enough that your risk is significantly decreased.

For example, if your company is generating free cash flows of $2M, you will usually get a valuation of $10M. That is the market rate for a startup that's breaking out. (It can change based on other factors, of course, but that is the starting point.) As a public company, that $2M is worth about $30M. You might look at that difference and claim "unfairness", but it is the price difference between concentrated risk and unconcentrated risk. To put it simply, if that wasn't the price difference in risk then most deals would not be made - either the startup would refuse to sell or the large company would refuse to buy.

Honestly, if this is your first company you are going to think that any price isn't fair. And when you don't accept the price, you'll be horrified when the company loses its value a little later. And then next time, you'll understand the price difference and you'll sell.

But the important thing is to keep building companies - I've started quite a few, and there is no job like it!

Comment Re:Retire at 20 (Score 5, Insightful) 358

If he started a company in his teens, I doubt he wants to relax the rest of his life...

He should sell. The reason small companies sell to large companies is to decrease concentration of risk for their owners. He, as an owner of a small company, needs to deconcentrate his risk. He will have another company he wants to work on - he probably already has some ideas. It is far easier to do that after selling your first company, and far harder to do that after missing the only opportunity to sell.

The simple fact is a cash out event gives you great options for your future work. If you don't sell, there is a high risk that the company will fail before you can personally cash out - this is true of all start-ups.

Comment Re:Solar powered jet engine (Score 1) 590

That's no problem at all using unobtainium, of course!

Actually, my math is off by a factor of 10 - I didn't convert kg to N correctly. The corrected result is:

FlyingMass = OtherStuff + 0.525 * FlyingMass

So your aircraft has to be half solar cells, roughly speaking. And, yes, the solar cell area is a bit on the large size...

Comment Re:Solar powered jet engine (Score 4, Informative) 590

To inject some math into the discussion:

ThrustToKeepFlying = FlyingMass / LiftToDragRatio
PowerToKeepFlying = ThrustToKeepFlying * Velocity = Velocity * FlyingMass / LiftToDragRatio

Typically LiftToDragRatio is about 20 or so. Airplanes don't really make sense unless they are faster than other vehicles, so Velocity needs to be 100-300 m/s. (Typically, jets fly just under Mach 1, where they have the least drag/greatest power)

FlyingMass = AircraftMass + PayloadMass + EngineMass + PowersourceMass

Since we are using unobtainium to build our aircraft, it doesn't weigh anything. And we'll just say that we can fly arbitrarily large airplanes for a single passenger, so PayloadMass is essentially zero as well.

The best solar cells are about 300W/kg (http://en.wikipedia.org/wiki/Solar_panels_on_spacecraft), and the best electric engines are about 6 kW/kg. So

FlyingMass = OtherStuff + PowerToKeepFlying / 300 + PowerToKeepFlying / 6000 = OtherStuff + 0.0035 * PowerToKeepFlying

FlyingMass = OtherStuff + 0.0035 * ( 300 * FlyingMass / 20 )

FlyingMass = OtherStuff + 0.0525 * FlyingMass

OtherStuff = 0.9475 * FlyingMass

So this says that as long as your airplane and payload are under about 95% of the engine / power source mass, it is at least possible. Structures that light are not really an issue - the real issue is only flying during the day and in good weather. (And, of course, it would cost an arm and a leg!)

Comment Re:Efficiency (Score 1) 87

A physical connection is not required, nor necessarily helpful. Wires have resistance, after all. With an arbitrarily large transmission array wireless losses can get arbitrarily small - as an example, a visible laser (just a very focused and high frequency electromagnetic wave) transmits virtually all of the energy to the target.

Comment Re:CAFE Kills (Score 1) 1184

This simply isn't true. Do the math - there are two things that can kill you here, momentum change and energy change. To make it simpler, let's use the elephant and flea car, which are, of course, perfectly elastic:

setup: Elephant and flea car approach each other, both going 50 meters/second.
collision
aftermath: Elephant car continues at the same velocity and direction. Flea car now has doubled velocity and reversed direction.
Velocity change for elephant car: approximately 0 meters/second
Velocity change for flea car: 150 meters/second - hitting a brick wall would be far better, at only 50 m/s
Energy change of elephant car: approximately 0 J
Energy change of flea car: approximately 22,500 * mass J

size matters!

Comment Re:I'm in a nitpicking mood. (Score 3, Informative) 75

Not really - ion propulsion trades "energy squared" for "propellant flow rate". So the large fuel tank (100 kg, say) has been replaced with a much smaller one, around 1 kg, for the same thrust. Here's the trade details:

1. Trading a 350 Isp Hydrazine thruster for a 35,000 Isp ion drive - it uses 1/100th the propellant for the same total impulse (thrust*time)
2. The thrust decreases dramatically typically - but for small satellite station-keeping that doesn't matter
3. The power requirement/N thrust gets ridiculous - from about 3.5KW/N to 350KW/N

Comment Re:Already happening (Score 2) 380

Actually, that is incorrect. You can certainly sue someone that creates an item for their own personal use that infringes your patent. It is just unlikely to work, so most people don't. But suing for the value of a "lost sale" is well established - and since patents allow 10 times damages in the case of willful infringement, it may even be economical.

Comment Re:gun safe? (Score 4, Insightful) 646

Um, those statistics are idiotic. Perhaps people that are about to commit suicide go out and buy a gun? Perhaps people that live in high murder rate areas buy and carry more guns?

And of course, the #1 - gang members are the majority of gun murders, both giving and receiving. And, of course, they carry guns.

Uncontrolled statistics do not convey useful information.

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