An Introduction to Zero-Point Energy

CalPhysics.org ^

[tpaine]

"I'm afraid I don't understand what you're driving at, either. Could you spell it out for us?"

'Cin' can't explain, - because he's playing a semantic game, [about the word 'push'] with the point at issue, -- in an effort to show how clever he is, vs the supposedly 'inept' author.
The issue:

"The propellor or the jet engine of an aircraft push air backwards to propel the aircraft forward. A ship or boat propellor does the same thing with water. On Earth there is always air or water available to push against. But a rocket in space has nothing to push against, and so it needs to carry propellant to eject in place of air or water."
_________________________________

Perfectly simple point made above.
-- If you are on the ground you must push against it to move forward.
-- If you are in the water you must push against it to move forward.
--- If you are in the air you must push against it to move forward.
--- If you are in space you can't push against it to move foward, you must eject something away from you.

I submit that 'cinfla' can use his large surplus of internal hot air for this purpose.

[Quix]

Some insist it already HAS had a profound impact . . .


affording bases on the moon, Mars and some perhaps even Io or some such.

But then, who can know.

[Doctor Stochastic]

Only if your errors are independent.

[XEHRpa]

Sorry, cinfla is right. The easiest example to show it is the rocket, which is a jet engine that carries its own intake onboard (i.e., all the inlet air and pressure is self-contained). A rocket in space certainly needs no air to push upon... it is purely a question of momentum transfer. In air breathing systems, thrust is developed both by momentum transfer (engine thrust) as well as by pressure differentials developed across the inlet and exhaust structures.

This is why the SR-71 becomes so damned efficient at Mach 3+... most of its thrust is developed by the pressure differentials. The actual engine thrust (momentum flux) is only like 35% of the total thrust, but it is still needed to set up the velocity fields which generate the pressure differentials. If I recall, most of the SR's thrust at high Mach is from pressure differential across the inlet spike (and a lesser amount across the afterburner funnel). The higher the Mach, the less total thrust that is actually coming from engine thrust.

So someone else's comment about engineer's and physicists both not writing well misses the mark. It was clearly written by a physicist since an Aero Engineer or Mechanical Engineer with a fluids background would not make this mistake.

My favorite (and best) prof of all time was, in fact, a German rocket scientist who worked for von Braun in the Fatherland. He was one of "our Germans," (though he was actually Ukranian) brought to the US after WWII. Every shuttle launch, until he retired, NASA would fly him down to the Cape as a consultant. He came to class, always dressed formally, and had the total 1 hour lecture always memorized, and I'm talking heavy duty equations. "Vir haff dis trust tairm, und vir integreeren dees oober tay-ta won to tay-ta too." I had no problem since my grandparents spoke the same way... sounded perfectly natural zu mir.

He insisted on calling the roll every day (like a Prussian schoolmarm), always butchering the names. One day, one of the students corrects him on the pronunciation, and he repronounces it, exactly as he did the first time. The student corrected him again, telling him that the name was Ukranian. Ol' Prof Hnatiuk got red in the face and said "I'm Ukranian, und eets prro-nounced [blah-blah]".

When we got back our first midterm, a four question test, the grades were given by a number in the 0 to 4 range (most likely 2 or below). Some kids were real interested on how this translated to letter grades, so they asked him what the grading scale was. "Zeero to forr," he replied looking perplexed. When they demanded to know letter grades that corresponded to these numbers, he reeled it off the cuff, saying 4 was an A, 3 = B, 2 = C, "und so weiter" (etc.) A whiner complained "that's not fair, you have to get a perfect paper to get an A." The old professor, never really adjusting to uppity American students got red in the face, and proclaimed "Gott, heez an A; Me? I'm a B. You?" and then he just shook his head with a snicker. He went on to say that if anyone had problems with the grades, you could talk to him after class. I debated it, but decided to just listen to how the early ones went before committing. Not only did he not give out a single additional point, but he actually reduced a few grades upon finding extra mistakes.

Professor Bohdan T. Hnatiuk was definitely "take no prisoners" with undergrads, but he had a soft spot for grad students. I never learned more during a semester than when he manned the chalk. God rest his soul.

[anymouse]

This is a proven hoax. ZPE has been debunked years ago.

Use some common sense, man.

[sourcery]

This is a proven hoax. ZPE has been debunked years ago.

Do you refer to the existence of ZPE, or to its usability as an energy source?

[donh]

Actually, even if it's real, it's everywhere and exactly the same everywhere. It's entropic energy. It's useless unless somebody repeals the Second Law of Thermo.

Half a mo' there. Didn't Hawking propose that Black Holes were detectable because the boundary quantum uncertainty at a critical distance around a black hole would produce a net detectable outflow of photons? A black hole detector seems like it might be a keen working device to me. Or is the critical region around a black hole entropy-irrelevant?

[donh]

Oh, come on. If you want to go forward, you got's to throw something backwards. Newton's laws rule. All else is window dressing. Go get in a rowboat and row against the current--it's pretty obvious. Pressure differentials sound pretty dern cool, but it's just a different, and, unless you design high speed craft, pretty distracting way to re-organize how you think about the distribution of forces, which in no way frees you from the fundamental requirements of the equal-and-opposite law.

[donh]

This is a proven hoax. ZPE has been debunked years ago.

Someone better let the physics community know about this, since most physicists seem to take the casimir confirmation as definitive evidence in ZPE's favor.

[CobaltBlue]

He may be right but he did not do a good job of explaining why he's right. In the context of the story that was being told, the example was almost a throwaway. It takes great skill to write a short example and make it coherent.

Most scientific concepts can't be boiled down into a sentence or two and do it total justice.

When you take away the long-winded explanations and the complex examples, and boil it all down to a couple of sentences, the original statement was probably as correct as anything you, yourself, could say in a sentence or two.

If you think you can explain it better in a sentence or two, please feel free. It doesn't appear that he can.

[donh]

Use some common sense, man.

If common sense was a relevant criteria for quantum mechanics, we'd still be communicating by vacuum tube, and the internet would have a rotary dial addressing mechanism.

[spodefly]

Will this zero point energy stuff run my SUV so I can get those damn hippys off my ass about it using too much gas?

[A CA Guy]

Saw Zero Point Energy and thought this was a Clinton Presidency thread!~

[mcsparkie]

"pushing" against the air which is a popular misconception

It makes sense if you think of the necessity to "push" on the air to expel it rearward at a high velocity, imparting to it the necessary momentum, which is also increased in the forward velocity of the propellor.

[sourcery]

Will this zero point energy stuff run my SUV so I can get those damn hippys off my ass about it using too much gas?

Consider a ZPE-based engine as a pie in the sky, wild blue yonder, very outside chance, extreme longshot lottery ticket. In other words, no one really knows, but I wouldn't count on it.

[mcsparkie]

When a passenger in an airplane feels pushed against his seat as the airplane accelerates

An airplane passenger's body is not accelerated by the jet engine. It is accelerated by the seat. Thus we feel the seat pushing against us.

[mcsparkie]

The propellor is also an airfoil. The "faster" airstream on the front side produces significant lift.

Ooops...You just said the same thing as that the vacuum on the front is sucking the propellor forward!

[Physicist]

A common misconception by laymen is that the force is derived from "pushing against" the water/air as in pushing against a wall. In reality, the force is derived from the acceleration of the water/air. The force would be the same in a vacuum for the same amount of water/air accelerated even though there would be no air/water to push against.

It's not a misconception at all. Pushing against a brick wall (or against the ground) is the same thing as pushing against a mass of air or pushing against a jet of hydrazine in a hard vacuum. In each of these cases, it's Newton's Third Law that moves you about. In the case of a brick wall or a planet, the reaction mass is gigantic (never infinite, however), whereas in the case of hydrazine molecules, the reaction mass is tiny. The principle is the same, though. The differences are only quantitative.

[Lessismore]

Was this absurd statement really written by someone with a physics background?

Highly unlikely. It may have started out with a manuscript or notes from a physicist, but it looks like the usual science popularization work of a tech writer trying to make it intelligible for the masses (including those masses providing monetary support for the institution).

[dinodino]

Earth should be uppercase...