science

Chas A. Egan, Charles H. Lineweaver calculated how run-down the universe is as things disappear into the ultimate run-down state of black holes (where you can’t do any work with what gets sucked in). Unlike previous calculations, they included freakishly big ones ( a billion times the mass of the sun) rather than the average (10 million times the mass of the sun) which account for most of its run down-ness: entropy.
The new results for entropy in Boltzmann units are: early universe (10^88); now (10^104); maximum (10^122).
(BTW entropy units are joules per kelvin – can someone remind me are the units of temperature itself, energy, or is it unitless)
Ron Cowen has a good summary of the paper at Science News, where he mentions the following:
“Entropy quantifies the number of different microscopic states that a physical system can have while looking the same on a large scale. For instance, an omelet has higher entropy than an egg because there are more ways for the molecules of an omelet to rearrange themselves and still remain an omelet than for an egg”.
Entropy is surely about macrostates vs microstates, if we had a name for a particular arrangement of molecules in an omelet, it would have high entropy. We don’t, there are many ways to smash an egg and still call it an omelet, so they are low entropy.
Does this mean that entropy is meaningless? No, but it means that it is relative to a particular system. The amount of potential work that can be done by system A on B depends not on some absolute measure of the free energy of A, but how much of that free energy is useful to B.
There is a relationship between the energy exchange between systems and information exchange, so the above paragraph could describe a relationship between two systems where the meaning of A was not absolute, but relative to B. One person’s high entropy omelet is another persons’ very special low entropy omelet with a name.

Mark Gimein has a good post about Special Relativity, that makes some excellent points:

That it could just as easily be called the theory of constancy (of the speed of light), and that the best way to read about it is from Einstein’s own layman’s explanation.

But more than that, that it is a theory of a flexible space and time background, introduced to resolve the impossibility of both (a) the summed relative motion (i.e. non fixed speed) of objects to or from light beams and (b) the (always observed) fixed speed of objects to or from light beams when measured against (c) the same fixed, universal co-ordinate system (clocks and measuring sticks).

Instead of ditching (a) or (b), Einstein ditched (c).

(a) was proven mathematically, (b) was proven by observation and (c) was assumed as obvious common sense based on experience.

Special relativity is a triumph of science over the senses and never trusting instinct, yet the Einstein myth sometimes creates the idea of the opposite – of following intuitive hunches. Yes, but only if they could be backed up with evidence. His creative thinking should not be confused with quasi-spiritual or artistic acceptance of intuition without reason.

Summed relative motion is obvious (two trains travel towards each other at their combined speed) and constancy of speed of light is empirically proven, therefore the insight Einstein had was to reconsider what seemed immutable – the fixed background of space and time.

Or was it? Einstein was taught by Lorentz and the idea of spatial contraction (admittedly, of objects not the space itself) to resolve the speed of light paradox was principally his. Like all things the truth is less clean than the fable. Special relativity was a conceptual breakthrough (principally in the linking of space and time), but still part of a continuum of thought.

Anyway. Mark’s post is a really good digest of the background of Special Relativity in qualitative terms: see here.

A decade ago, physicists discovered a real problem: most of our energy is missing. Something, call it dark energy, is causing the expansion of the universe to accelerate.

Paul Gough, a prof at Sussex has an extremely interesting and simple idea that links dark energy to information entropy.

He looks at the energy of the universe not just in terms of overall mass and radiation, but particles at particular temperatures. The average energy per bit is estimated to give a measure of increasing information energy which creates effects that are equivalent in magnitude to dark energy.

His idea seems to be roughly as follows:

The number of particles in the universe is roughly constant but the universe is increasing in volume. As gravity clumps matter together stars form, creating hot spots which increase the average energy per particle and therefore total information energy.

As the universe expands its ‘bit space’ increases, and the information density decreases, rather like putting the same data on a larger hard drive.

The natural reduction in information energy density caused by expansion is lessened by the hot spot effect and the total information energy increases. The data on the bigger hard drive got bigger.

The equation showing the energy per bit is co-incidentally the same as that showing the characteristic value of a cosmological constant and it gives a value which is as low as the surprisingly low one that fits observation.

Assuming that the cosmological constant and information energy co-incidences are real, a resulting ‘negative-pressure state parameter’, equivalent to dark energy, causes the increased rate of expansion of the universe.

Link

Earlier paper here.

In the 60s, Freeman Dyson proposed that as intelligent life grew beyond the resources of a planet, it could re-engineer local solar system matter to create orbiting satellites which would be able to use more of their sun’s free energy. The result would be that looking at a star, it would appear dimmer, and in the extreme, invisible, and instead you would see the re-radiation of infra-red light from the satellites.

The Dyson sphere is a specific case of the inevitable thermodynamic result of the phenomenon of life. Without life, a star radiates high energy photons, which are re-radiated by a planet as many more low energy infra-red photons, with a black body distribution at around room temperature. This results in an increase in entropy. The localized, low entropy order of living things, act as little entropy machines which accelerate the overall production of this entropy.

In other words, no matter how weird the Dyson sphere sounds, it is a viable example of the mechanism by which the inevitable extreme increase in entropy (from the waste of a low-entropy grabbing, industrial society, operating for any significant period of time), could be achieved. There might be others, but they will all result in the same thing – low temperature black body spectrum waste.

For the first time, using the IRAS infra red telescope, a serious search has been conducted for Dyson Spheres, or dim stars, and the results are essentially negative. There are a few candidates but it is very difficult to differentiate them from specific cases of Red Giants or glowing, stellar heated, dust clouds.

Link

Is this a reasonable question.

Is the matter in the universe arranged in a fractal pattern? A new study of nearly a million galaxies suggests it is .

Although there is no mechanism to describe this, I would have been extremely surprised if it weren’t the case. It implies that matter itself is balanced on a knife edge state of existence between order and chaos and suggests two competing, balanced, forces, applied algorithmically, somehow (a mapping). It also suggests that the mechanism for creating fractal structures such as weather patterns and living things is related to something bigger. Perhaps a cosmic level natural selection via the 2nd Law?

“To summarize: these things sit on uranium, drink bleach and eat solid rock”.

Link