While in college, Ray Palmer discovered a tiny fragment of white dwarf star material that had fallen to Earth. An astronomy and physics student doing research on the nature of size and matter, Ray theorized that if he were to grind a lens from this fragment and focus ultraviolet light through it, he could shrink anything struck by the light down to a fraction of its original size. Ray rushed off to his laboratory, tried the experiment, and found that it worked exactly as he had imagined, with one tiny little catch: the objects he shrunk became unstable and exploded moments later.
A couple of days later, a disillusioned Ray and some friends became trapped in a cave-in while out spelunking; Ray was forced to risk instability and use the shrinking lens on himself in order to escape the cave and save the lives of his friends. For some reason, however, Ray didn't explode and returned to his normal height. In fact, the shrinking lens worked on his body much better than he had expected, and he developed a set of control devices that gave him limited control over his weight as well as his size. Ray later hypothesized that some unknown "x-factor" in his genetic makeup prevented his atoms from becoming unstable, though many scientists now believe that Ray's ability to shrink was actually made possible by the "metagene" possessed by all humans.
Keeping his discoveries a secret, Ray created the secret identity of the Atom and embarked on a career of crime fighting in Ivy Town, Connecticut. For a while, the new Atom operated strictly on his own, battling such nemeses as Chronos the Time Thief, the Computer Crooks, and the Floronic Man. The Atom was voted in as the League's second non-founding member after a battle with the mysterious Mister Memory, who was later exposed as perennial JLA adversary Amos Fortune. Ray later became a full-time physics professor at Ivy University, and married his longtime sweetheart Jean Loring, though the couple was divorced only two years later. Just before his divorce, the Atom traveled to the Amazon basin, where he discovered the Katarthans, a race of six inch tall aliens.
After he and Jean split up, Ray returned to live amongst the aliens, and fell in love with Taren, a beautiful Katarthan princess. The Katarthans and their village were soon wiped out by a horrible fire and the Atom returned to Ivy Town, only to find that one of his friends had written a book exposing Ray's secret identity in his absence. After battling various foes, such as Strobe, Humbug, and Swarm, Ray learned that a US Government agency had engineered the destruction of the Katarthans, in order to induce his return to the States. He avenged the Katarthans by permanently reducing the agents responsible for the massacre to six inches in height. Ray returned to Ivy Town just long enough to bid his friends farewell, and then briefly went into hiding.
He was later approached by Amanda Waller, who convinced him to fake his own death, so he could secretly join the espionage unit known as the Suicide Squad. As a part of this mission, Ray went undercover and Adam Cray served in the Suicide Squad as the new Atom. Adam was killed by Blacksnake and Ray resumed the role of the Atom. Later still, he joined the then-current Justice League on a semi-active basis.
Ray was preceded as the Atom by Al Pratt, a member of the Justice Society of America. While Ray, and the Atoms who followed him, had shrinking powers, Al's superpower was superhuman strength. The two of them worked together occasionally during JLA/JSA team-ups. Al died during a battle against Extant.
In time, Ray and Jean were able to be friends again. In the divorce she had received half of his patents. As a gesture of friendship, Jean decided to sign them back to him. Little did he know that this was but one of many facets to Jean's deadly scheme to win Ray back. Since their divorce, Jean had somehow become seriously deranged and believed that the only way to be reunited with Ray was to force the issue. Incredibly, she devised an elaborate plan to endanger Sue Dibny, wife of Elongated Man Ralph Dibny. Jean was privy to the fact that every year on her birthday, Ralph would be absent solving a custom-tailored mystery devised by Sue. She bypassed the Dibnys' security by shrinking down and traveling via the phone lines into their home. She then entered Sue's body and obstructed the blood flow to her brain. To cover up this evidence, Jean scorched Sue's body.
Jean knew that this event would send all the heroes scrambling to protect their loved ones and — hopefully - drive Ray back into her arms. Jean employed two other schemes to cover her tracks. First, she faked her own murder , then she hired Captain Boomerang to kill Robin (Tim Drake)'s father Jack. She supplied Jack Drake with a gun to defend himself, hoping that Boomerang would be killed and that everyone would believe he was Sue's killer as well. Eventually, Dr. Mid-Nite's autopsy of Sue's body revealed the truth, and the Atom himself elicited a confession from Jean. She was promptly admitted to Arkham Asylum . With Jean's incarceration, Ray was overwhelmed with despair, and shrank continuously until he vanished completely into the microscopic or subatomic.
Ray's legacy lives on with Ryan Choi utilizing a version of his costume and shrinking device to become the current Atom.
Ray Palmer is a hard-working, dedicated man. In fact, "dedicated" is hardly the word for it; "driven" is a little closer to the truth. Once Ray starts working on a problem or puzzle, there is absolutely no stopping him. This single-minded pursuit of his goals is more than a little responsible for Ray's shattered marriage, though it has occasionally come in handy to Ray the crime fighter. In spite of his obsessiveness, Ray is a level-headed hero and a basically likable human being.
During the missing year, Palmer's technology is employed by Supernova to shrink and grow in size in order to enter and exit the bottle city of Kandor.
During the Countdown Event a Monitor asks the Source Wall "what is the solution to the great disaster", it answers "Ray Palmer". The Challengers from Beyond (Kyle Rayner, Donna Troy and Jason Todd) are currently scouring the reformed Multiverse for the former Atom, who just might hold the key to saving reality from a crisis of unparalleled proportions.