I have heard from many people that the Flash is faster than Superman.
But how do we know this? Can you give me the comic issue/continuity and the basic plot summary?
It's already been established that all of the Flashes can move past light-speed via the Speed Force. As for Superman, he's never shown to move at light-speed while running inside a planetary atmosphere.
- This image should answer your question, though. This scan was taken from Flash v2, #220.
Flash states that Superman is moving at over 2000 miles/sec, which is also over 120,000 miles/minute, and also 7,200,000 mph. That's Mach 9350. I believe this is that fastest that I've seen Superman move under the Earth's atmosphere. He can, however, break light speed in the vacuum of outer space.
Superman has raced the Flash several times over their history but it is considered a given that if the Flash decided to run at his maximum, Superman who lack the environmentally-protective speed-force aura, is unable to move at his maximum without causing catastrophic environmental damage due to his moving near light speed.
- Barry Allen reminds Kal-El, even though we have raced several times in the past, ultimately, "I allowed you to participate and ultimately YOU CANNOT beat me in a race. Not now, not ever."
An important caveat to this statement is that Superman CAN move faster than light in space and has been shown to do that on several occasions in the New 52.
- Outside of a planetary atmosphere he has proven to be able to achieve speeds faster than light, traveling from Pluto to Earth in a matter of minutes. Whether this is due to him achieving superluminal speeds or by warping space around him has not been discerned or disclosed. His current top speed is estimated by this travel time at 16 to 20 times the speed of light!
As to why Superman cannot move faster than light in atmosphere, I submit to you an XKCD article explaining what happens when something moves at near-relativistic speeds in atmosphere: Relativistic Baseball. Totally worth the read.
False, Superman can move faster than lightspeed. On Earth he won't fly at lightspeed because this could be catastrophic to the planet Earth, Flash doesn't have that problem because part of his powers prevent any damage to the planet. In Space Superman does not have that limitation and can let it rip. In a recent issue of red Hood and The Outlaws , Superman flew from Pluto , back to Earth in the same amount of time, or faster , than the Outlaws were able to teleport back to earth. That is 4.67 billion miles , in seconds
The thing here is that people are concentrating on the running... yes... Flash can outrun Superman because Superman does not need to run, therefore he is not used to it. On the other hand.... if he was flying, it might be a different story.
Earth-Pluto (4.67 billion km of distance) in minutes is in the bases of the 17 billion km/h that Batman refers in the JLs (aprox.16xlightspeed). Maybe aprox. 20 billion km/h.
In The Flash: The Human Race (1998), the Cosmic Gamblers get the Flash to run in a race for the fastest being in existence, where losing means the destruction of planet Earth. The Flash counter bets with the Gamblers that he can run faster than they can teleport. The Flash then gathers more Speed Force than ever and makes a move in less than a Plank Instant (smallest unit of time), arriving at destination before instant transportation of the Gamblers is achieved.
Being faster than teleportation is certainly faster than Superman, as we've never seen Superman able to catch up with teleportation. This is all scaled by the end of this interesting video:
In The Flash Rebirth #3 (2009), Direct competition between the Flash and Superman did clearly demonstrate and acknowledge that during a chase where the Flash easily outruns Superman. See Thaddeus Howze answer for the illustration.
And in Flashpoint (2011), the Flash does even better as he uses the Speed Force to travel back in time (some speed overflow you could say). Modern Age Superman can't time travel with his speed alone. See Can Superman reverse time in comics by flying faster than speed of light?.
Everyone here doesn't realize Flash is faster then superman by a lot no matter space or earth. People are saying flash can run at the speed of light and superman can do it, then others are saying superman flies faster in space. Regardless flash is able to run so fast he can go back in time and he can travel through dimensions because he is so fast regardless. There have even been recent flash comics were Mr and Ms Quick run so fast they can fly. Flash is the fastest Man alive friends.Flash traveled at a speed faster than a planck second which is the smallest period of time so basically flash is able to beat time it self in a race
Superman is faster than Flash. Please realize that just because Flash says I've been holding back or Flash leave superman shocked or stunned at how fast he is does not represent an admission on superman's part that he agrees. Superman holds back also and for good reason. Superman has unlimited strength or close to, which means his sheer will determines how fast he can go. If required superman can push himself to run faster than he ever has so his limits has never been shown. At those times Flash let loose and zooms way out ahead of superman superman could have dug in and catch up. Instead he marvels at how fast flash is. How often would superman encounter a human that fast? He will always underestimate flash's limits because he himself cannot know if there is another level until it happens. I'm sure one day the writers will write it correctly. I even believe that superman will also discover the speed force whether with flash help or not. Just recently Superman has discovered a new power cause super flare... even that he has psionic powers https://m.youtube.com/watch?v=zexXH3lS8Uw The reason superman has to always be the greatest is because he is history... the first super hero in comics as we know it. plus, it makes sense... superman has a healing factor which is why he defeated doomsday. he and doomsday fell and he and dooms day came back. I believe doomsday is the experiment on krypton that created the modern kryptonian. We all know that the gold superman prime is superman highest form and flash could not run fast that that version of superman. That version of superman would likely be able to access the speed force. How far away is current superman from that superman (superman prime) ?
The bottom line is Superman is faster, but that's ok... flash is still the fastest Earthling, but not determined to be fastest human since kryptonian are human too.