Category Archives: Physics

New Source of Comets – the Asteroid Belt ?

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Found on the Planetary Society Blog:

So far, it has generally been assumed that all comets originate from the other two known reservoir regions: the Oort cloud and Kuiper belt. The main asteroid belt is home to, well, asteroids, not comets. But Hsieh and Jewitt have proven that there are comets in the main asteroid belt, and that they almost certainly formed there.

Pretty interesting given that the current assumption is that all water on Earth arrived via cometary bombardment early on in the life of the solar system.

You can read more on Henry Hsieh’s website and peruse the abstract of their paper “A Population of Comets in the Main Asteroid Belt” from Science Magazine.

Venus Express Telemetry is Good!

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The last piece of the puzzle is in, the ESA have confirmed that they have telemetry from Venus Express and have held a press conference to announce everything looks A-OK with the spacecraft. Congratulations to all involved!

Emily quotes Don McCoy, Venus Express Project Manager saying:

In fact we have quite a bit margin of fuel on board. We allocate extra fuel for a bad launch, for maneuvers on route, [and everything was nominal] so we probably have enough fuel to do the extended mission, and quite frankly I think we could do another one after that. We have enough fuel for 4 and a half to 6 years.

This could be a really interesting mission..

Venus Express Arrives!

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The Planetary Society’s Emily Lakdawalla is reporting from Darmstadt that the European Space Agency’s Venus Express is in orbit!

She does sound one note of caution though, saying:

while the S-band signal has indicated that the spacecraft has shut down its main engine properly, it does not yet indicate the full health of the spacecraft; that will only happen at 11:13 local time, when (if) they detect the X-band signal from the spacecraft’s high-gain antenna.

So congratulations on getting there, and here’s hoping the spacecraft reports it is in good shape!

Dark Energy Stars, a Replacement for Black Holes ?

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Here’s an interesting thought, what if black holes didn’t exist but instead a collapsing star underwent a quantum critical phase change, turning into a rather peculiar, but QM compliant, object ?

This is what two physicists from LANL believe could be happening.

The report in New Scientist says:

[…] Chapline and Laughlin found some answers in an unrelated phenomenon: the bizarre behaviour of superconducting crystals as they go through something called “quantum critical phase transition” (New Scientist, 28 January, p 40). During this transition, the spin of the electrons in the crystals is predicted to fluctuate wildly, but this prediction is not borne out by observation. Instead, the fluctuations appear to slow down, and even become still, as if time itself has slowed down.

“That was when we had our epiphany,” Chapline says. He and Laughlin realised that if a quantum critical phase transition happened on the surface of a star, it would slow down time and the surface would behave just like a black hole’s event horizon. Quantum mechanics would not be violated because in this scenario time would never freeze entirely. “We start with effects actually seen in the lab, which I think gives it more credibility than black holes,” says Chapline.

With this idea in mind, they – along with Emil Mottola at the Los Alamos National Laboratory in New Mexico, Pawel Mazur of the University of South Carolina in Columbia and colleagues – analysed the collapse of massive stars in a way that did not allow any violation of quantum mechanics. Sure enough, in place of black holes their analysis predicts a phase transition that creates a thin quantum critical shell. The size of this shell is determined by the star’s mass and, crucially, does not contain a space-time singularity. Instead, the shell contains a vacuum, just like the energy-containing vacuum of free space. As the star’s mass collapses through the shell, it is converted to energy that contributes to the energy of the vacuum.

The team’s calculations show that the vacuum energy inside the shell has a powerful anti-gravity effect, just like the dark energy that appears to be causing the expansion of the universe to accelerate. Chapline has dubbed the objects produced this way “dark energy stars”.

A really intriguing possibility and one that, they believe, could be verified or disproved in 5-10 years.

Schrödingers Cat, Observers and the Participatory Anthropic Principle

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Following on from a posting on Rich Boakes blog I left the following comment which struck me as interesting enough to be a post of its own right here.

Rich posits the question of what would happen if Schrödingers Cat had mirrors in its own box, would it collapse its own waveform ?

My guess is not, simply because it will never be capable of observing the moment of its own death as if it were able to it would, by definition, still be alive. However, I then brought up the following..
Strangely enough, I’ve been thinking about this problem from a different viewpoint – if the box with the dead/live cat in is opened by an observer inside a locked room who then dies before being able to pass on the information does the waveform collapse when he sees it and stay collapsed, or does it not collapse from the point of view of an observer outside the room?

I was wondering if it collapsed and then uncollapsed, but I suspect from a QM point of view it’s likely to be one of the two former cases – and my gut reaction is that it would be the latter..

So again it begs the question of who/what exactly constitutes an observer ? There is the participatory anthropic principle that says that conscious life is necessary to the universe in order for the collapse of QM waveforms to occur, but I think that’s a particularly long straw to grasp..