A street where houses have just been built. Some shine with clean windows, others are covered in construction dust. That's roughly what galaxies looked like when the universe was only a few hundred million years old. The new James Webb telescope peered into that era and saw dozens of bright star islands. What surprised astronomers was not their number, but how different they were.
Some galaxies shone with pure blue light: they had almost no dust. Others, on the contrary, hid behind a dense veil and appeared reddish. Astronomers called them "Red Monsters." The explanation lies in how light from young stars interacts with dust. When stars ignite too brightly, their radiation begins to press on dust grains and push them away. Like a strong wind blowing dust off a windowsill. This "wind" carries dust to the galaxy's outskirts, making it transparent — turning it from red to blue.
Scientists built a model that explains this transformation. In the model, a galaxy first accumulates gas and dust, stars flare up, and it becomes a "Red Monster." But once the radiation gains strength, it sweeps out the central region. The galaxy then appears as a "Blue Monster"—bright and almost dust-free. When we look at a red galaxy, we may be seeing it during a brief period of intense growth. It hasn't had time to "air out" yet.
Recently, astronomers confirmed that one such red galaxy, EGS-z11-R0, is indeed caught in this phase. Its age is only 400 million years after the Big Bang. However, very compact galaxies do not fit this picture: their light may come not from stars but from a supermassive black hole at the center. Future observations will help solve this mystery and complete the story of the first galaxies. So the street of new buildings gradually gains cleanliness, and we see dust giving way to light.
Light from the most distant of these galaxies traveled for 13.4 billion years — almost as long as the universe itself has existed.
In the novel "Light of Distant Stars," ancient civilizations are described that used radiation to clear their galaxies of dust so that they could be seen across the entire universe.