phys-energy   37

Theory of Self-Reproducing Automata - John von Neumann

Comparisons between computing machines and the nervous systems. Estimates of size for computing machines, present and near future.

Estimates for size for the human central nervous system. Excursus about the “mixed” character of living organisms. Analog and digital elements. Observations about the “mixed” character of all componentry, artificial as well as natural. Interpretation of the position to be taken with respect to these.

Evaluation of the discrepancy in size between artificial and natural automata. Interpretation of this discrepancy in terms of physical factors. Nature of the materials used.

The probability of the presence of other intellectual factors. The role of complication and the theoretical penetration that it requires.

Questions of reliability and errors reconsidered. Probability of individual errors and length of procedure. Typical lengths of procedure for computing machines and for living organisms--that is, for artificial and for natural automata. Upper limits on acceptable probability of error in individual operations. Compensation by checking and self-correcting features.

Differences of principle in the way in which errors are dealt with in artificial and in natural automata. The “single error” principle in artificial automata. Crudeness of our approach in this case, due to the lack of adequate theory. More sophisticated treatment of this problem in natural automata: The role of the autonomy of parts. Connections between this autonomy and evolution.

- 10^10 neurons in brain, 10^4 vacuum tubes in largest computer at time
- machines faster: 5 ms from neuron potential to neuron potential, 10^-3 ms for vacuum tubes
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april 2018 by nhaliday
Autoignition temperature - Wikipedia
The autoignition temperature or kindling point of a substance is the lowest temperature at which it spontaneously ignites in normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical ignites decreases as the pressure or oxygen concentration increases. It is usually applied to a combustible fuel mixture.

The time {\displaystyle t_{\text{ig}}} {\displaystyle t_{\text{ig}}} it takes for a material to reach its autoignition temperature {\displaystyle T_{\text{ig}}} {\displaystyle T_{\text{ig}}} when exposed to a heat flux {\displaystyle q''} {\displaystyle q''} is given by the following equation:
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november 2017 by nhaliday
Static electricity - Wikipedia
Electrons can be exchanged between materials on contact; materials with weakly bound electrons tend to lose them while materials with sparsely filled outer shells tend to gain them. This is known as the triboelectric effect and results in one material becoming positively charged and the other negatively charged. The polarity and strength of the charge on a material once they are separated depends on their relative positions in the triboelectric series. The triboelectric effect is the main cause of static electricity as observed in everyday life, and in common high-school science demonstrations involving rubbing different materials together (e.g., fur against an acrylic rod). Contact-induced charge separation causes your hair to stand up and causes "static cling" (for example, a balloon rubbed against the hair becomes negatively charged; when near a wall, the charged balloon is attracted to positively charged particles in the wall, and can "cling" to it, appearing to be suspended against gravity).
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november 2017 by nhaliday
Resonance in a Pendulum - YouTube
The vibration of any given washer is able to transmit its energy only to another washer with exactly the same frequency. Since the length of a pendulum determines its frequency of vibration, each pendulum can only set another pendulum vibrating if it has the same length.
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september 2017 by nhaliday
Europa, Enceladus, Moon Miranda | West Hunter
A lot of ice moons seem to have interior oceans, warmed by tidal flexing and possibly radioactivity.  But they’re lousy candidates for life, because you need free energy; and there’s very little in the interior oceans of such system.

It is possible that NASA is institutionally poor at pointing this out.
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september 2017 by nhaliday
Lecture 3: Global Energy Cycle
solar flux, albedo, greenhouse effect, energy balance, vertical distribution of energy, tilt and seasons
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august 2017 by nhaliday
Muscle, steam and combustion
Vaclav Smil’s Energy and Civilization is a monumental history of how humanity has harnessed muscle, steam and combustion to build palaces and skyscrapers, light the night and land on the Moon. Want to learn about the number of labourers needed to build Egypt’s pyramids of Giza, or US inventor Thomas Edison’s battles with Nikola Tesla and George Westinghouse to electrify homes and cities, or the upscaling of power stations and blast furnaces in the twentieth century? Look no further.
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august 2017 by nhaliday
Controversial New Theory Suggests Life Wasn't a Fluke of Biology—It Was Physics | WIRED
First Support for a Physics Theory of Life:
Take chemistry, add energy, get life. The first tests of Jeremy England’s provocative origin-of-life hypothesis are in, and they appear to show how order can arise from nothing.
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august 2017 by nhaliday

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