Are the Galxies Expanding?

[Rhondazvous]

I was reading Isaac Asimov’s book How Did We Find Out About the Universe. He says scientists noticed the star Sirius was red shifting. This goes against my understanding of the raisin bread dough model of universal expansion. According to what I understand of this model, the d ark energy acts as a kind of yeast while the space between the raisins/galaxies is the dough. Just as yeast doesn’t make the raisins expand so dark matter doesn’t infiltrate galaxies causing them to expand.

But if Sirius is red shifting that means intra galactic expansion. I always thought of dark energy and gravity acting like oil and water—not mixing. But if dark energy can defeat the gravity that holds the galaxies together, what keeps it from infiltrating atoms and defeating the weak force that holds atoms together? This is scarier than a renegade higgs boson playing around in a false vacuum.

I first knew Asimov as a science fiction author. But he was also a scientist and professor and has written many books expounding real science to young readers. This lends weight to what he says here.