Ultimate Fighter Muay Thai Martial Arts respect fight honor logo shirt
The Ultimate Fighter Muay Thai Martial Arts respect fight honor logo shirt thing here is not that we haven’t found aliens, but that we are learning so much about the universe so quickly. 20 years ago nobody knew that there are huge underground oceans on Europa and Enceladus, and methane lakes on Titan. 40 years ago there was no evidence of life at hydrothermal vents or life in deep ocean sediments—organisms that use forms of biology quite unlike that of the familiar organisms here on the surface. 25 years ago there was no evidence of even a single planet around another star! Now we know of thousands. The real number, in our galaxy alone, is probably hundreds of billions. The appropriate attitude here, I’d say, is a mix of giddiness and caution. Giddiness, because the rate of discovery right now is downright astonishing. Caution, because we still have so far to go in answering the big question: Are we alone?

Ultimate Fighter Muay Thai Martial Arts respect fight honor logo shirt, Hoodie, Sweater, Vneck, Unisex and T-shirt
Best Ultimate Fighter Muay Thai Martial Arts respect fight honor logo shirt
The description from Richard Muller quoted in the question is a simplification of reality meant to help people better visualize how the Ultimate Fighter Muay Thai Martial Arts respect fight honor logo shirt of spacetime works. In reality the galaxies are moving through spacetime in a complex fashion, based on the combination of all the forces acting on them, primarily the gravity of nearby galaxies and galaxy clusters. In the case of the Milky Way and Andromeda, these two galaxies are part of a gravitationally bound cluster of galaxies, called the Local Group. The dominant force that determines the movements of objects within the cluster is the combined gravitation of all the mass in the cluster, and not the expansion of spacetime. In other words, the gravitational attraction that the Milky Way and Andromeda have for one another that is drawing them together is stronger than the expansion of spacetime between them that would otherwise push them apart, and thus attraction wins and the two galaxies are on a collision course. In the same vein, the gravitational force that holds the earth in orbit around the sun is stronger than the expansion of spacetime between the earth and the sun (the expansion of spacetime at that distance being very small), and so the earth’s distance from the sun is not increasing for that reason. Likewise you are not flying apart because the molecular bonds holding the atoms in your body together are stronger than the minuscule expansion of spacetime between them in your body. The Local Group as a whole, however, is moving away from other galaxies and galaxy clusters to which it is not gravitationally bound, due to the expansion of spacetime.
