Meru Foundation Research:The Negentropic Gradient: Penrose, Zohar, and R. Shneur Zalman of Lyadi

First, consider again, the Sun’s role as a low-entropy source. There is a common misconception that the energy supplied by the Sun is what our survival depends upon. This is misleading. For that energy to be of any use to us at all, it must be provided in a low-entropy form. Had the entire sky been uniformly illuminated, for example, with some uniform temperature – whether that of the Sun or anything else – then there would be no way of making use of this energy (whatever kind of creature we might imagine having evolved to try to cope with it). An energy supply in thermal equilibrium is useless. We, however, are fortunate that the Sun is a hot spot in an otherwise cold background. During the day, energy reaches the Earth from the Sun, but during the course of the day and night it all goes back again into space. The net balance of energy is (on the average) simply that we send back all the energy that we receive.¹⁴

However, what we get from the Sun is in the form of individual photons of high energy (basically yellow high-frequency photons because of the Sun’s high temperature), whereas this energy mostly goes back into space in the form of photons of low energy (infrared, low frequency). (This photon energy relation comes from Planck’s formula E=hv and his insights into black-body radiation; see §21.4). Because of their higher energy (higher temperature) there are many fewer photons from the Sun than there are photons going back into space, because the total energy carried by them is the same coming in as going out. The Sun’s smaller number of photons means fewer degrees of freedom, and therefore a smaller phase-space region and hence a smaller entropy, than in the photons returned to space. The plants make use of this low-entropy energy in their photosynthesis, thereby reducing their own entropy. Then we take advantage of the plants to reduce ours, by eating them, or eating something that eats them, and by breathing the oxygen that the plants release; see Fig. 27.9.

Penrose Pic

Fig 27.9 The Earth gives back the same amount of energy that it receives from the Sun, but what it receives from the Sun is in a much lower entropy form, owing to the fact that the Sun’s yellow light has higher frequency than the infrared that the Earth returns. Accordingly, by Planck’s E=hv, the Sun’s photons carry more energy per photon than do those that Earth returns, so the energy from the Sun is carried by fewer photons than that returned by the Earth. Fewer photons mean fewer degrees of freedom and therefore a smaller phase-space region and thus lower entropy than in the photons returned to space. Plants make use of this low entropy energy in photosynthesis, thereby reducing their own entropy, and we take advantage of the plants to reduce ours, by eating them, or eating something that eats them, and by breathing the oxygen that the plants release. This ultimately comes from the temperature imbalance in the sky that resulted from the gravitational clumping that produced the sun.

But why is the Sun a hot spot in a cold sky? Although the detailed story is complicated, it ultimately comes down to the fact that the Sun – and all other stars – have condensed gravitationally from a previously uniform gas (of mainly hydrogen). Whatever other influences are present (primarily nuclear forces), the Sun could not even exist without gravity! The ‘lowness’ in the Sun’s entropy (considerable remoteness from thermal equilibrium) comes from a huge reservoir of low entropy that is potentially available in the uniformity of the gas from which the Sun has gravitationally condensed.

¹⁴In fact, overall, the Earth sends back just slightly more energy than it receives. Ignoring the issue of human burning of fossil fuels, which finally returns some energy received from the Sun and stored in the Earth many millions of years ago (and, on the other side of the scales, ignoring the accompanying global warming that results from the ‘greenhouse effect’ whereby the Earth traps a little more of the Sun’s energy than previously), there is the hearing of the Earth’s interior through radioactive decay, this energy being very gradually lost into space through the atmosphere. See §34.10.