On Jan. 12, 1967, James Bedford, a psychology professor at Glendale College in California who had just died of cancer, took his first step toward coming back to life. On that day, the professor became the first person ever frozen in cryonic suspension, embedded in liquid nitrogen at minus-321 degrees Fahrenheit.

Bedford was neither the first, nor the last, to attempt the impossible — beating death at its own game, according to Michael Shermer’s book “Heavens on Earth: The Scientific Search for the Afterlife, Immortality, and Utopia” (Henry Holt), out Jan. 9.

With scientific advancements exploding at an exponential pace, some believe the Grim Reaper could soon be out of business.

Here are three ways scientists are striving for immortality that are getting so close to success that they would amaze even Bedford — if he ever wakes up.

Cryonics

Cryonics is the process of suspending a just-deceased person in a frozen state until the remedy for what killed them has been discovered. Then, theoretically, the person can be thawed out and cured.

Science will only consider a person properly preserved if they can be revived with all of their memories intact. Many question whether those currently frozen can be successfully revived.

Currently, the cryonic process “vitrifies” the brain, turning it “into a glass-like substance.” Caltech neuroscientist Christof Koch — echoing the opinion of many experts — said it would be “utterly amazing” if this change to the brain’s chemistry didn’t destroy the synapses that hold memories, writes Shermer.

One major champion of freezing is Ralph Merkle, a board member at the Alcor Life Extension Foundation cryonics facility in Arizona. Having performed their first human cryopreservation in 1976, Alcor now has 153 deceased patients frozen in its facility — including Bedford — and almost another 1,000 people have made arrangements to be preserved there when they die. Between Alcor and the Cryonics Institute in Clinton Township, Mich., there are at least 290 people cryonically frozen in the US.

Merkle, 65, said critics of cryonics are like those in the early 1900s who believed mankind could never reach the moon.

“If you can say that technology 100 or 200 years from now will be incapable of reviving someone who is cryopreserved, then you’re making [unknowable] statements about what future technology cannot do,” Merkle told The Post.

Merkle denies that current freezing technologies can’t preserve memory, claiming that “vitrification . . . is providing excellent preservation of synaptic structure” and that experiments with roundworms have shown memory retention after revival from freezing. He also notes that memory preservation occurs not just in the synapses, but also in the biological structures surrounding them. Furthermore, Merkle believes that in the next few decades or perhaps century, technology will allow repairs to be made to bodies while they’re frozen, so they can be thawed with all the flaws and ailments corrected.

“At some point in the future, we will have technology that can take the damaged structure [of the brain], analyze it and recover the information,” Merkle says. “Once you can recover the information, you can restore the damaged structure with the memory and the information content intact.”

Singularitarians

Some believe that we will one day extend our lives by merging with technology. Singularitarians predict there will be a theoretical future moment when artificial intelligence will overtake and either merge with or replace human intelligence.

The premier evangelist for the singularity is scientist and futurist Ray Kurzweil, Google’s director of engineering, who created the first text-to-speech synthesizer and the CCD flatbed scanner.

As technology continues to accelerate, Kurzweil believes we’ll reach a point where “the world will change more in a decade than in a thousand centuries, and as the acceleration continues and we reach the singularity, the world will change more in a year than in all pre-singularity history,” writes Shermer. “When that happens, humans will achieve immortality.”

‘Medical technologies will add one additional year every year to your life expectancy’ - Ray Kurzweil

Kurzweil explained his vision for life extension in a 2016 Playboy interview quoted in Shermer’s book. “By the 2030s we will have nanobots that can go into a brain non-invasively through the capillaries, connect to our neocortex and basically connect it to a synthetic neocortex that works the same way in the cloud,” he said. “So we’ll have an additional neocortex . . . and we’ll use it . . . to add additional levels of abstraction.”

Not only will nanorobots give us greater brain power, they will also make us healthier and extend our life spans while we’re alive, Kurzweil argues.

“As they gain traction in the 2030s, nanobots in the bloodstream will destroy pathogens, remove debris, rid our bodies of clots, clogs and tumors, correct DNA errors and actually reverse the aging process.

“I believe we will reach a point around 2029,” Kurzweil added, “when medical technologies will add one additional year every year to your life expectancy.”

Mind Uploading

Proponents of “mind uploading” go further than Kurzweil, believing that you won’t even need a body or a brain to exist, because one day human consciousness will live on a computer.

The key to uploading the brain is the connectome, which is a comprehensive map of the brain’s neural connections and pathways that equals the sum total of one’s brain function. Scientists are currently trying to figure out how to assemble and preserve the connectome of a brain. Once that’s achieved, they will theoretically be able to download a human being’s conscious mind.

To this end, the Brain Preservation Foundation, of which Shermer is on the advisory board, announced a prize for companies that can figure out how to preserve brains and, by extension, their connectomes. In 2016, 21st Century Medicine in Fontana, Calif., was awarded the Brain Preservation Prize for small mammals after freezing a dead rabbit’s brain at temperatures even colder than vitrification and thawing it to show “preservation of brain ultrastructure sufficient to establish that the ‘connectome,’ or totality of all brain cell to brain cell synaptic connections, can be preserved for at least 100 years.” This earned them just under $27,000 in prize money. The other 75 percent, worth just under $108,000, will go to the first team to “successfully preserve a whole large animal brain in a manner that could be adapted for humans.”

To freeze the rabbit, 21st Century Medicine used a new technique called “aldehyde-stabilized cryopreservation,” which opens up “the blood-brain barrier and allow[s] the cryoprotectant to enter the brain without causing brain shrinkage.” Using the same process, the company has also preserved several pig brains and has submitted one for consideration for the large mammal prize.

Shermer visited 21st Century during the freezing process and saw both the rabbit and pig brains in question. Though he notes that none of the three rabbit brains the company froze “showed any visible signs of ice formation or damage,” one of the pig brains “had a dime-sized ice smudge in the occipital lobes near the cerebellum.”

“Not a good sign,” he notes, “but this is not yet a perfect science.”

While clearly fascinated by the topic, Shermer believes that too many factors need to come together for us to conquer mortality anytime soon.

“There are scientists working to extend our upper-age ceiling through various medical technologies, but for now the bookmakers’ odds-on bet is that no one alive today will live beyond 125 years,” he writes.

“Even if medical science raises the age roof by a few years or decades, the dream of living centuries or millennia is a vaporous one.”