Orrin do you believe in voodoo? (Work with me here.)

No.

"...the total uncertainty in their measurements is plus or minus 10% if they allow for unknown sources of error."

How, praytell, does anyone allow for unknown sources of error with a straight face?

JD:

By subtracting the sum of the signal and the known error sources.

Kind of like algebra.

OJ:

How exceedingly odd of you to hoist them for their awareness, in advance, of realizing expectations.

Yet another difference between science and religon. Scientists actively guard against such a thing; religionists exclude everything else.

Orrin's side is still stuck on the angels dancing on the head of a pin stage, Eugene.

Jeff:

Relativity passes latest test (Physics Web, Oct 20, 2004)

Harry,

You can believe in God and still appreciate the accomplishments of scientists.

I am coming to the conclusion that it's a game for Orrin, just like his regular digs at soccer. He enjoys being perverse for the sake of being perverse.

And I want a refund from ACME, the pins dancing on the head of the Orrin Judd wax puppet aren't working.

OJ:

Yes, and?

Jeff:
To take the predicted value plus known errors, subtract this from the observed result, and atttribute the difference to unknown errors, while algebraic, is not good science (algebra is not science). Widespread application of this procedure would make any theory non-falsifiable. All this is irrelevant though in the current case.

From the article cited, their measurement of the Lense-Thiring frame dragging effect is within 1% of the value predicted by theory (~2 m/yr), but this value is small compared to effects due to variations in the Earth's gravitational field. These variations are known to exist but their values are only approximately known -- the 10% error bound is only a SWAG, and its magnitude is controversial.

With such a large margin of error, you could equally well say that Newton's theory has been confirmed and there is no frame dragging, with small unknown errors.

jd,

So how did they get funding for the expensive tests?

Something isn't adding up. The article is leaving out some stuff that the writer decided was too hard for most of its readers.

Eventually General Relativity will be superseded by new discoveries and theories just as Newtonian Mechanics was.

Imagine our entire universe being just a thin membrane in a multi-universe, like foam dancing on top of a wave.

Eugene:

Where are they?

Eugene:

Bad enough to believe in Darwin, but Voodoo?

Orrin,

Where are ... "they"?

Where are the new discoveries and theories to supersede General Relativity? We'll have to wait for a genius or three hundred to come up with them.

Or do you mean the Fermi Paradox: If we're not alone in the universe, where are the aliens?

Maybe off exploring the vast realms that we can't perceive? Maybe we are truly alone, in which case the "created in His image" suddenly takes on a much more literal meaning?

I'm just a tiny mite, my guesses aren't good for much.

Orrin,

I don't "believe in" Darwin any more than I "believe in" Pythagoras or Humboldt.

The Voodoo was just a joke!

JD:

Well said. However, this experiment isn't the final word on the subject.

Several years ago, scientists set about attempting to detect the gravity waves inherent to General Relativity. There was no way the first device could do that, if for no other reason than it lacked the required sensitivity.

I think this is why they call them experiments--see what works before pressing on.

Eugene:

There may be no Fermi paradox at all. It may well be that in this universe, it simply isn't possible to get here from there.

What a nasty mess error analysis is, which is why most scientists don't even attempt to do it "right" in the mathematical sense. I've been trying unsuccessfully to find out how the polls we've been deluged with work. I assume that they're quoting statistical errors, so if they say that Bush has 48%, with an error of 3% from a sample of 2000 voters, then that means that if you ask some different sample of 2000 voters, you'll get an answer of 45-51% 68.5% of the time (assuming these are 1-sigma errors; 95% if they're 2-sigma errors, but nevermind that). But as partisans on both sides like to point out, there is an entirely different sort of error to consider--systematic error, such as biases in your experiment. For example, some say that polls taken on weekends are biased towards Democrats. Others say that polls are missing likely voters who are young and energized about voting this time who don't fit in the "likely" categories typically used. Or cell phone only users. Or whatever. And this sort of error (which also turns up in scientific experiments, of course) is much harder to quantify, and requires you to really understand your experiment and the system you're trying to measure.

All of which is to say, even if the error analysis in this experiment makes sense (haven't read the paper), there's no way the author of the article understands it enough to properly describe it.

Jeff: If humans are around in a few hundred million years, we'll be there. That's why the fact that they're not here is important.

There are many, many answers to the question: "Why haven't any aliens contacted Earth ?"

Many of them could be true at the same time.

· They have, of course, and we know about it, we just don't understand.
· They have, of course, but the powers that be, possibly including the powers-behind-the-power, have kept that knowledge secret.
· They're here, but undercover.
· They have a "Prime Directive".
· Being alien, they don't have any drive to mess with Earth, for trade, to enlighten us, eat us, conquer us, etc.
· They don't like to travel.
· Our world is wrong for them, and they don't have any reason to risk death to mess with primitive savages.

Until humans can pick out Earth-like worlds, which is a few years from now, and extensively study them for any signs of advanced life, the answer to the alien question says more about the person answering it than it does about the question.

OJ:

Wrong.

There is no known way to carry enough energy to both get out of the sun's gravity well and stop at the other end. (Never mind sink all the heat Thermodynamics says must be a byproduct of all that energy expenditure.)

Nor is there any known way to discern the habitable planets from the others for all but the closest stars.

Does that mean it will never happen? No.

But it is silly to discount the real possibility that Fermi's paradox has far less than meets the eye simply because getting here from there is irrevocably difficult to the point of impossibility.

Michael:

Excuses, not reasons

Jeff:

As deterministic as your Darwinism.

oj:

You don't feel your eyebrow lice, either, but that doesn't mean that they don't exist.

What are you looking for, a giant neon arrow, "Space Aliens Here ====>>" ?!?

Jeff:

Solar sails and hibernation. It's a one-way trip anyhow, so what does it matter how long it takes ?

As much evidence as of the lice.

I can show you the lice.

It's a matter of taste.

People like Orrin cannot stand uncertainty, so they posit their beliefs to be the same as facts. That way they achieve 100% certainty, at the cost of 0% precision.

Grownups learn to live with uncertainty. We are not quite sure, but our error bars are not infinitely long.

Gravitational theory as currently read is certainly incomplete -- nobody claims different -- and a complete theory may be quite a bit different.

But the outcomes will not be very different from what today's theory works out at. Did you focus on that uncertainty? Awfully small, wasn't it?

Jeff: I think you meant to address your reply to my post, not oj. Can you please explain how leaving the sun's gravity and entering that of another star is fundamentally any different from leaving the Earth's and going to another planet? Other than scale, seems perfectly analogous to me.

I also think you're forgetting the immense time scales involved. Hundreds of millions of years is something that I don't think we can even imagine, but you sure can get a lot done in that time. And if the Earth hadn't had the status of its life reset several times by impacts, intelligent life could have easily been that far ahead of where it is now.

As for visiting every star, once you get going (and with enough time), that's no problem. Seems to me it's like the settling of America--by the time of the revolution (some 250 years after the initial colonists), the Appalachias were still about the limit of major settlements. By about 125 years later, pretty much everything was filled in.

I think that the answer to the Fermi paradox is simply that several of the terms in the Drake equation are vanishingly small, despite the hopes of SETI types (who now hope there are hundreds to thousands of advanced civilizations in the galaxy, down from the millions they were touting not too long ago).

brian:

Anything that hasn't happened that Jeff's scientific beliefs suggest should have must therefore be physically impossible--else his mind would have to open.

Harry:

That you can show us the lice is the precise point.

OJ:

If all you can manage is an ad hominem attack, how about just not bothering.

Brian:

Sorry for the confusion.

Fundamentally, it isn't any different. Just much, much bigger. That deep well needs energy to overcome--lots and lots of it. Which brings along a host of other problems, the most notable of which is sinking the waste heat.

Presume you actually get going at some reasonable speed for the nearest star. How the heck are you going to stop?

If the star is the same size as the sun, it will take precisely as much energy to avoid blowing through the new solar system as it took to get out of this one.

And that completely ignores changine direction. If habitable planets are one per 100,000 stars, the odds are very long one against being able to detect one so as to know which star to even aim at.

It would be folly to say it is impossible, but it is pure ignorance to presume it is certain.

Michael:

A solar sail would probably get you all the way to the Oort cloud.

Observations of fact are not ad hominem.

You need an instrument to see the louse. Same with gravity.

OJ:

The point in question is whether Fermi's paradox is in fact a paradox, not the openness of my mind.

Therefore, your comment is an irrelevant ad hominem attack. It is every bit as illuminating as the ad hominem attacks on that record breaking tthread of last week.

So how about just not bothering?

The inability to grasp paradox--the insistence on impossibility--is closedness.

When I put a book on a table it stays--that doesn't explain "gravity.".

There you go again.

Close mindedness or not is irrelevant.

Fermi's paradox is only exists to the extent They can actually get here from there.

Your insistence on inevitability blithely ignores some very fundamental problems that might turn out to be insolvable.

Acquaint yourself with the physics involved, then come back with an informed discussion about what is required to make getting here from there possible, never mind practical.

Oh, one other thing, you said I insisted such a thing is impossible. Would you please provide the quote?

The paradox is that they can't be unsolvable yet they are unsolved, suggesting there's no one else out there.

"... they can't be unsolvable ..."

Back that one up with something other than an unsupported assertion.

BTW--I take it an apology is forthcoming for misquoting me?

"getting here from there is irrevocably difficult to the point of impossibility"

Stop quote mining.

My most recent and dispositive statement on the subject is:

"It would be folly to say it is impossible, but it is pure ignorance to presume it is certain."

Also, given your tendentious defense of the word "any" last week, I find it surprising you equate "...to the point of impossibility" with "impossible."

They are clearly not the same.

If your standard is most recent it can never be dispositive.

How iis the point of impossibility the same as possible?

OJ:

It absolutely can be dispositive, as it expanded upon what I said before: to the point of impossibility does not include impossibility itself, therefore possible, but far from certain.

I note however, you have completely failed to address the argument: an additional reason why Fermi's paradox may in fact not be.

Typical of ad hominem attacks.

Jeff:

With a laser source, much further than the Oort Cloud, but OK. Certainly, at some distance, a solar sail isn't much good anymore.

So, we send out two vessels, one filled with fuel. At some point, the ships furl their sails, attach to each other, and the cargo ship pushes the other with rockets.
Once the fuel is exhausted, the cargo ship is jettisoned.

When the passenger ship reaches its destination, they possibly use some fuel to slow down a bit, then tack around the new sun for a while, (months, years), until they've slowed enough to orbit their chosen world.

Simple.

There's no question that humans could eventually reach other worlds, if we choose; it's merely a question of how long we'd like to spend doing it.

I suspect that people will be leaving Sol on two-hundred-year journeys at the end of the 21st century.

The point of impossibility isn't impossibility? Then shouldn't it be the point of poissibility?

OJ:

Clearly the statement means up to, but not including, especially when taken in context of "extremely difficult," and what I said subsequently. But that's OK, OJ; given that ad hominem attacks are so empty, I suppose it is asking a bit much to demand logical consistency. So, please, by all means go ahead. Just don't expect you are showering yourself in glory.

Michael:

It isn't that simple--it will take as much fuel to slow down as it did to speed up. More in fact, since there will be no counterpart laser at the far end. The remaining fuel will have to have enough energy to both equal that in the original tanker, as well as all the energy the laser supplied.

I don't think the sums add up.

Which highlights the part of the journey most neglect. Getting there is one thing. Stopping is something else altogether.

And the other problem, less obvious, is that of heat. Any energy transformation is going to be inefficient; the inefficiency comes at the cost of waste heat, all of which is notoriously difficult to sink in a vaccuum.

The faster you try to go, the worse the problem gets, too.

In fact, all the problems are compounding. The faster you want to go, the more energy, hence weight, hence more energy to accelerate that increased weight, hence more run ins with Thermodynamics. And the faster you are going at the far end, the more energy--and more fuel remaining-- required to stop.

Does that mean impossible? No.

But absent some completely revolutionary breakthrough, it basically means we can get there if we don't mind taking nearly forever to do it.

And just because a breakthrough is required doesn't mean there is actually one to be had.

Therefore, it is entirely possible Fermi's Paradox is useless as a theological axe-grinding tool simply because they can't get there from here.

No one knows for sure, but to discount the possibilty of impossibility out of hand is intellectually dishonest.

Jeff:

it will take as much fuel to slow down as it did to speed up

Is that certain? How about some fancy celestial mechanics to profit from the gravity of objects in the target solar system?

After all, when we fly a probe out to Saturn and use Jupiter for a swing-by gravity assist, the increase in speed gained from approaching Jupiter is not afterward canceled out as the probe leaves Jupiter behind.

So, why not run at the target star or one of its very large planets almost head-on? That should slow down the spaceship fast.

That still leaves open the question of how to power the return trip, of course.

Eugene:

Good point.

I left the orbital mechanics stuff out to avoid lengthening the discussion.

In principle, you are right. We used Jupiter to accelerate the Voyager spacecraft by going by behind the planet. The result slowed Jupiter slightly, will greathly speeding up Voyager.

But unless you had slowed considerably (lots of fuel), you would find yourself in a comet like orbit and would have to spend thousands of years, and more fuel, to circularize the orbit anywhere near your habitable planet target.