能量的來源(The Source of Energy)
能量的來源
概說生命的物理和化學特性必須始于太陽--確切地說，是太陽的核心，而非地球。 能量來自太陽的核心。 在這里，太陽不停地以光和熱的形式向空間傾瀉出能量。
數十億計的氫原子核在太陽的核心碰撞并且聚變生成氦。 在此過程中一部分原本儲存于原子核中的能量被釋放出來.
太陽所產生的光和熱需要每秒將六億噸氫轉化為氦。 這樣的轉化在太陽中已經持續幾十億年了。 核能在太陽的核心被釋放為高能的伽馬射線。 這是一種電磁射線，就象光波和無線電波一樣，只是波長要短得多。 這種伽瑪射線被太陽內的原子所吸收，然后重新釋放為波長稍長一些的光波。
這新的射線再次被吸收，而后釋放。 在能量由太陽內部一層層滲透出來的過程中，它經過了光譜中x射線部分，最后變成了光。 在此階段，能量到達我們所稱的太陽表層，并且離散到空間而不再被太陽原子所吸收。 只有很小一部分太陽的光和熱由此方向釋放出來，并且未被阻擋，穿越星空，來到地球。
a summary of the physical and chemical nature of life must begin, not on the earth, but in the sun; in fact, at the sun's very center. it is here that is to be found the source of the energy that the sun constantly pours out into space as light and heat. this energy is liberated at the center of the sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium, and in doing so, release some of the energy that is stored in the nuclei of atoms.
the output of light and heat of the sun requires that some 600 million tons of hydrogen be converted into helium in the sun every second. this the sun has been doing for several thousands of millions of years. the nuclear energy is released at the sun's center as high-energy gamma radiation, a form of electromagnetic radiation like light and radio waves, only of very much shorter wavelength. this gamma radiation is absorbed by atoms inside the sun to be reemitted at slightly longer wavelengths. this radiation, in its turn is absorbed and reemitted. as the energy filters through the layers of the solar interior, it passes through the x-ray part of the spectrum eventually becoming light. at this stage, it has reached what we call the solar surface, and can escape into space without being absorbed further by solar atoms.
a very small fraction of the sun's light and heat is emitted in such directions that after passing unhindered through interplanetary space, it hits the earth.
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