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## Comment Re:Delta-V is not measured in km/s (Score 1)93

V = Velocity
Delta = Change
Delta-V = Change in Velocity

Aka, from velocity X to velocity Y, the delta-V would be Y - X
Obviously the units of "Y - X" are going to be the same as the units for Y and X.
Thus delta-V has the same units as velocity.
Aka km/s or similar.

## Comment Re:Seriously long tether needed (Score 1)93

I can't even begin to imagine how one is going to have a hypervelocity anchor attach to a comet rather than just blowing it up, and how any anchor attached to a comet would withstand 5 Gs. Comets aren't exactly the most structurally sound of objects...

## Comment Re:Calculations (Score 3, Informative)93

They're talking about the theoretical strength of SWNTs, which is upwards of 120GPa. But the highest ever measured SWNT strength, last I read, was around 60Ga - and that's the properties of individual tubes (ropes don't even approach it).

Whenever you're reading something and it mentions needing a "carbon nanotube tether", toss whatever you're reading in the "sci-fi" category. Not even the hard sci-fi category. And all for what - a ~6 year Pluto transit time? Lame.

Don't they have anything better to research?

Heck, even I can think of a more plausible approach than that - one that doesn't require unobtanium at least. Forget the "diamond anchor", land a microsat on it (approaching comet, not a retreating one). Yeah, that takes a lot of delta-V, but if it's just a microsatellite, then that's not a lot of mass. Then, forget about the "carbon nanotube tether"; use a space fountain between the large craft and the lander. Space fountains (such as paired coilguns, for example) are plausible with today's technology, requiring no unobtainium.

But the whole concept of delta-V from a comet is just not a worthwhile avenue to pursue either way. Way too much difficulty and mechanisms for failure for way too little reward.

## Comment Re:Their requirements are lacking (Score 3, Interesting)52

Most accidents occur at less than 40 mph; if "dozens of meters" equates to about 100 ft, that represents about 1.7 seconds at 40 mph. Assuming a coefficient of friction of 0.8, it is theoretically possible for a car traveling at 40 mph to stop in 67 ft; call it roughly 70 ft. If the system can apply the brakes within 500 ms, that's enough to be useful, although clearly it can't stop you from plowing into a car stopped in the fast lane of the highway.

Speaking of highways, the only reason people can manage to drive on highways is that the things you're most likely to hit are traveling in the same direction; if they were slaloming between stationary obstacles at 60 mph most drivers would be dead, fast. What makes highway driving safe is that the closing speed between vehicles is usually modest; usually on less than ten fifteen miles per hour. So actually the system might have more effect on the highway so long as speed discrepancies are in the normal range.

## Comment Re:Alert! (Score 3, Funny)319

The "consensus" of scientists was pretty clear on that whole phlogiston thing for a while, wasn't it... and then on the whole "caloric" thing that replaced it.

Right, but the astrologers have been consistent all along.

## Comment Re: Alert! (Score 1)319

I'll bet that for practical purposes you can't personally confirm general relativity, RNA to DNA reverse transcription, the role of the Coriolis effect in the formation of seasonal thermoclines in the ocean, or the number of stars in the Milky Way galaxy. It doesn't mean those things aren't science.

"I can't confirm it" isn't the same as "I am unable or unwilling to put the effort it would take."

## Comment Re:Or for slightly less per month (Score 4, Insightful)80

Depends on how much you use the car. Drive a brand new car off the lot to the used car dealer across the street, and you'll find the car is now worth about half what you paid for it. It takes a lot of 3.5 krona minutes to make that instantaneous depreciation seem attractive.

Now if you're like most suburban-dwelling American, you spend hours a day in your car, so it just makes sense to buy it, or lease it long-term. But if you lived and worked in Manhattan you'd be nuts to own a car for transportation unless you were a gazillionaire. Just the cost of keeping the car would exceed the cost of renting one on the rare occasions you'd need it.

I suppose most people in Copenhagen are in the same boat. It's far more walkable than most American cities and enjoys excellent bicycle and pedestrian public transit infrastructure. But every so often you and several of your friends might want to take a trip that's a little inconvenient to take by transit. If that's every day several times a day then sure, buy a car. But if it's only occasionally then it doesn't make sense to have a car sitting and depreciating in a garage somewhere.

## Comment Re:Alert! (Score 4, Insightful)319

Exactly. Science is not a democracy. We don't get to vote on the rules of physics, they are what they are even if we agree with them or not.

However we have no way of getting to know those rules except through a social process in which scientists read and argue about each others' research.

Trust me, if the majority of scientists hadn't agreed on Newton's laws of motions you'd never have heard of him. Of course then we wouldn't be having this technology-mediated conversation; we'd probably be throwing rocks at each other instead.

People that believe we should reduce carbon output and also believe that nuclear power will kill us all are rejecting science twice over.

Disproof by counterexample: me. I think we should reduce carbon output and I think nuclear power could be useful, provided that plant developers post a bond to cover the decommissioning costs. I won't bother to address your point about wind power, but I do recommend you take the the drive from Los Angeles to Palm Springs sometime. You might find it enlightening.

A true scientist would admit we know very little about the environment. Anyone that says they've solved the equation is either delusional or trying to sell something. I'm not buying.

And no true Scotsman puts sugar on his porridge.

Just because scientists don't know *everything* doesn't mean they know *nothing*, or that they don't know enough to have a more informed opinion than a layman.

## Comment Re:Does Sony also provide... (Score 1)115

Yes, there is. Even a flawless human eye couldn't resolve better than about 0,4 arcminutes.

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