Talk:Saitama/@comment-138.197.151.203-20190817164219/@comment-86.165.144.116-20190824141241

I do not think that his punches will be able to destroy entire galaxies. The space between stars is predominantly empty, more empty than any vacuum that can be artifically produced on Earth. Having said this, between stars, there is what is referred to as interstellar medium (gas and dust- mainly hydrogen) which accounts to 15% of the observable mass of the galaxy.

http://www.jb.man.ac.uk/distance/exploring/course/strobel/ismnotes/ismglxya.htm

Consecutive serious punches could only therefore realistically act on the nearest celestial body. If a planet, then the planet would break apart and would continue to move at speed until it interacts with another object or another force acts on it. Also, any light or energy produced is likely to dissipate.
 * The dominant cause would likely be the force of gravity pulling back on your motion.
 * Friction due to the interstellar medium - vacuum isn’t completely empty
 * Flying into stellar winds.
 * Colliding with dust and (micro-)meteorites.
 * Having more radiation pressure in front of you than in back.
 * Dynamical friction due to the motion through a field of many small masses, even if you don’t collide with any of them.

https://www.quora.com/Do-objects-slow-down-in-the-vacuum-of-space