هل يؤدي توسع الكون إلى جعل الفضاء الخارجي فراغًا?

لا ينتج فراغ الفضاء الخارجي عن توسع الكون, ولكن بسبب الجاذبية. في البداية, عندما نقول الفضاء الخارجي (الفضاء خارج الغلاف الجوي للكواكب والنجوم) هو “مكنسة” or is “empty”, we really mean that outer space is تقريبا empty or تقريبيا a perfect vacuum. في الواقع, even the most remote spot of outer space has gas, غبار, إشعاع, الجاذبية, and a whole host of other things. There is no such thing as truly empty space. If we tried to suck all the particles out of a certain volume, we could still never get it empty. There would still be things like vacuum fluctuations, الجاذبية, and dark matter, which can’t be sucked out. وقال مع ذلك, outer space is very close to empty compared to earth’s atmosphere. لماذا ا?

Every particle of matter, no matter how small, exerts a gravitational attraction on all other particles of matter. For small bits of matter like a hydrogen atom and for large distances like we see on the astronomical scale, the force of gravity is very weak. But it is not zero. Given enough time, gravity makes giant clouds of gas in space condense down despite the gravitational force being so weak. Soon after the Big Bang, the universe was filled with a nearly uniform soup of hydrogen and helium. Over billions of years, gravity pulled most of these gas atoms into stars. Inside the nuclear furnace of stars, hydrogen and helium were fused to form the heavier elements up to iron. Larger stars eventually died in an explosive supernova which created all the naturally occurring elements heavier than iron and spewed these heavier elements into space. متأخر، بعد فوات الوقت, these heavier elements condensed down under gravity to form small clouds and rocks. بالمقابل, the clouds and rocks gravitationally attracted each other to form asteroids, أقمار, and planets. Outer space is nearly empty because most of matter that used to be out there has literally fallen into an asteroid, كوكب, القمر, or star under the influence of gravity.

The expansion of the universe only affects the distance between galaxies, and does ليس increase the distances between objects inside a galaxy. Atoms in your body, creatures on earth, planets in a solar system, and solar systems in a galaxy are all far too strongly bound by gravity and electromagnetism to be affected by the expansion of the universe. كنتيجة ل, the expansion of the universe cannot explain the relative emptiness of the space inside a galaxy.

ائتمان:HTTPS://wtamu.edu/~cbaird/sq/2013/10/08/how-does-the-expansion-of-the-universe-make-outer-space-a-vacuum/