[url]http://ca.news.yahoo.com/scientists-smell-old-socks-help-fight-deadly-malaria-103639365.html[/url]

This could be important!

"Quantum Theory Gets Physical

New work finds physical basis for quantum mechanics"

[url]http://www.sciencenews.org/view/generic/id/332557/title/Quantum_theory_gets_physical[/url]

[quote]Physicists in Canada and Italy have derived quantum mechanics from physical principles related to the storage, manipulation and retrieval of information.

The new work is a step in a long, ongoing effort to find fundamental physical motivation for the math of quantum physics, which describes processes in the atomic and subatomic realms with unerring accuracy but defies commonsense understanding.

“We’d like to have a set of axioms that give us a little better physical understanding of quantum mechanics,” says Michael Westmoreland, a mathematician at Denison University in Granville, Ohio.

Quantum theory’s foundations currently rest on abstract mathematical formulations known as Hilbert spaces and C* algebras. These abstractions work well for calculating the probability of a particular outcome in an experiment. But they lack the intuitive physical meaning that physicists crave — the elegance of Einstein’s theory of special relativity, for instance, which says that the speed of light is constant and that laws of physics don’t change from one reference frame to the next.

Giulio Chiribella, a theoretical physicist at the Perimeter Institute for Theoretical Physics in Ontario, Canada, and colleagues based their approach on a postulate called “purification.” A system with uncertain properties (a “mixed state”) is always part of a larger “pure state” that can, in principle, be completely known, the team proposes in the July Physical Review A.

Consider the pion. This particle, which has a spin of zero, can decay into two spinning photons. Each single photon is in a mixed state – it has an equal chance of spinning up or down. The pair of photons together, though, comprise a pure state in which they must always spin in opposite directions.

“We can be ignorant of the part, but we can have maximal knowledge of the whole,” says Chiribella.

This purification principle requires the quantum phenomenon known as entanglement, which connects the parts to the whole. It also explains why quantum information can’t be copied without destroying it but can be “teleported” — replicated at a distant location after being destroyed at its point of origin.

Building on this principle, Chiribella and colleagues reproduced the mathematical structure of quantum mechanics with the aid of five additional axioms related to information processing. Their axioms include causality, the idea that a measurement now can’t be influenced by future measurements, and “ideal compression,” meaning that information can be encoded in a physical system and then decoded without error. Other axioms involve the ability to distinguish states from each other and the ability of measurements to create pure states.

“They nail it,” says Christopher Fuchs, a theoretical physicist at the Perimeter Institute. “This now approaches something that I think is along the lines of trying to find a crisp physical principle.”

Whether this new derivation of quantum theory will prove to the simplest and most physically meaningful remains to be seen.

“What is simple or physically plausible is a matter of taste,” says Časlav Brukner, a physicist at the University of Vienna in Austria who has developed an alternative set of axioms.

Some speculate that recasting quantum theory in terms of information could help to solve outstanding problems in physics, such as how to unify quantum mechanics and gravity.

“If you have lots of formulations of the same theory, you’re more likely to have one that leads to whatever the next physics is,” says Ben Schumacher, a theoretical physicist at Kenyon College in Gambier, Ohio.[/quote]

Earth has asteroid companion
[url]http://www.cbc.ca/news/technology/story/2011/07/28/science-earth-trojan-asteroid.html[/url]

[QUOTE]The moon isn't the only hunk of space rock that has been travelling around the sun with the Earth for ages.

Canadian scientists have discovered that the Earth is also accompanied by a "Trojan" companion — an asteroid that travels a constant distance ahead of it at all times, sharing nearly the same orbit around the sun...[/QUOTE]

[QUOTE=Jeff Gilchrist;267771]Earth has asteroid companion
[url]http://www.cbc.ca/news/technology/story/2011/07/28/science-earth-trojan-asteroid.html[/url][/QUOTE]

what happens to the the body problem if you put a fourth body affecting it ?

[QUOTE=science_man_88;267787]what happens to the the body problem if you put a fourth body affecting it ?[/QUOTE]It becomes a three-body problem with perturbations by the fourth, if the fourth body is much less massive (or more distant) than the most massive two bodies. In that case the fourth body's effect on the third body becomes mathematically convenient to calculate as perturbations to the three-body system rather than starting all over as a four-body problem.

[QUOTE=cheesehead;267790]It becomes a three-body problem with perturbations by the fourth, if the fourth body is much less massive (or more distant) than the most massive two bodies. In that case the fourth body's effect on the third body becomes mathematically convenient to calculate as perturbations to the three-body system rather than starting all over as a four-body problem.[/QUOTE]

Do [URL="http://en.wikipedia.org/wiki/Lagrangian_point"]Lagrangian Points[/URL] come into this somewhere?

I devised a neat excercise around this:
If three different masses are located at the vertices of an equilateral
triangle, and all are rotating with the same angular velocity in circular
orbits about their centre of mass, show that this satisfies Sir Isaac,
and find the angular velocity.
How about elliptical orbits?
Stability???

David

PS I've just read the article Jeff cited: Lagrange points have
everything to do with it!
It was known that Jupiter has asteroids at its L4 and L5 points,
but not the earth till now!

PPS treat earth/moon as one body.

[QUOTE=davieddy;267862]Do [URL="http://en.wikipedia.org/wiki/Lagrangian_point"]Lagrangian Points[/URL] come into this somewhere?

I devised a neat excercise around this:
If three different masses are located at the vertices of an equilateral
triangle, and all are rotating with the same angular velocity in circular
orbits about their centre of mass, show that this satisfies Sir Isaac,
and find the angular velocity.
How about elliptical orbits?
Stability???

David

PS I've just read the article Jeff cited: Lagrange points have
everything to do with it!
It was known that Jupiter had asteroids at its L4 and L5 points,
but not the earth till now!

PPS treat earth/moon as one body.[/QUOTE]

(such as a satellite with respect to the Earth and Moon) is in the Wikipedia article already. so that stabilizes it distance to the earth wise so then it's almost dependent on the sun that it stays there.

[QUOTE=science_man_88;267866](such as a satellite with respect to the Earth and Moon) is in the Wikipedia article already. so that stabilizes it distance to the earth wise so then it's almost dependent on the sun that it stays there.[/QUOTE]
I think satellites are located at L1 or L2 (in line with earth and sun
and quite "close" to earth. OTOH I don't see why they couldn't try
to put a satellite at L4 or L5 (~93M miles away) or L3 (186M miles away on
the opposite side of the sun - communication would be a piece of cake!).

David

PS I was referring to the sun/earth Lagrange points.
I would guess that there were already satellites at the
earth/moon Lagrange points, but we don't hear much about
them.
.

[QUOTE=davieddy;267875]I think satellites are located at L1 or L2 (in line with earth and sun and quite "close" to earth.[/QUOTE]The Wikipedia article's "Past and present missions" table lists some. SOHO, ACE and WIND are in halo orbit or Lissajous orbit near Sun-Earth L[sub]1[/sub]. (Halo orbits and Lissajous orbits around L[sub]1[/sub] have two advantages over exact placement at L[sub]1[/sub]: 1. They're more gravitationally stable against perturbations by other Solar System objects, so require less fuel for station-keeping. 2. They keep the satellite out of the direct Earth-Sun line, making communication much easier. Halo orbits are periodical. Lissajous orbits wander farther and are quasi-periodical.)

WMAP, Herschel Space Observatory and Planck are near Sun-Earth L[sub]2[/sub]. James Webb Space Telescope will be in a halo orbit around L[sub]2[/sub]. Gaia will be near L[sub]2[/sub]. The Wikipedia article's "Future and proposed missions" table lists others.

[quote]OTOH I don't see why they couldn't try to put a satellite at L4 or L5 (~93M miles away) or L3 (186M miles away on the opposite side of the sun - communication would be a piece of cake!).[/quote]Actually, communication with either Sun-Earth L[sub]1[/sub] or L[sub]3[/sub] is made difficult by interference from the Sun, but a halo or Lissajous orbit takes satellites far enough out of line to allow clear-enough radio communication.

As for why not: there's been no good reason yet to put one at L[sub]3[/sub]. The STEREO probes will pass close to L[sub]4[/sub] and L[sub]5[/sub]. See [URL]http://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_points[/URL] for others.

[quote]I would guess that there were already satellites at the earth/moon Lagrange points, but we don't hear much about them.[/quote]No reason to have them there yet, with only a couple of minor exceptions. ARTEMIS is at Earth-Moon L[sub]2[/sub]. There may be some at L[sub]3[/sub] and L[sub]4[/sub] later.

THX for all that info Richard.

BTW I deliberately call them "Lagrange points" for two reasons:

1) The "Lagrangian" is of massive importance in theoretical physics,
as is his work on small oscillations in many particle systems.
2) I am inclined to think that "Lagrangian Points" have become accidently
so-called merely through confusion of the ideas.

I would be extremely surprised if either Euler or Laplace weren't aware
of them earlier. Or even Sir Isaac for that matter;)

David

[QUOTE=cheesehead;267905]No reason to have them there yet, with only a couple of minor exceptions. ARTEMIS is at Earth-Moon L[sub]2[/sub]. There may be some at L[sub]3[/sub] and L[sub]4[/sub] later.[/QUOTE]A nice com-sat in orbit around Terra-Luna L2 would make a far side landing mission possible. It could also facilitate a lunar radio telescope (creating a super-long base line array.)