Galactic Merger Rewires Your Sense of Time
Two massive galaxies are tearing each other apart in a slow-motion catastrophe that will take hundreds of millions of years to complete. We can now see it happening in real time rather than inferring it from theory alone.
Most accounts stop at the wreckage and move on, satisfied they've answered the question in the headline. But why we can detect galactic collisions at all matters more than the collision itself.
Mergers are how galaxies grow. Every large galaxy in the universe has consumed smaller ones. The Milky Way itself is still digesting the Sagittarius Dwarf, pulled apart by our gravity over the last billion years.
Current N-body simulations predict that Andromeda and the Milky Way will collide in approximately 4. 5 billion years. Not might collide. Will collide.
But here's what rewires everything. It happens in 4. 5 billion years, the solar system will be uninhabitable anyway. The sun will have exhausted its hydrogen and expanded into a red giant, vaporizing anything in the inner planets. Life on Earth will end around 1 billion years from now, when the sun's increasing luminosity makes our atmosphere unlivable. The galactic collision will be irrelevant because we'll have been gone for 3.
