Schrödinger's Cat Returns

Physicist Erwin Schrödinger devised a thought experiment known as Schrödinger's cat:

It attempts to illustrate what he saw as the problems of the Copenhagen interpretation of quantum mechanics when it is applied to systems large enough to be seen with the naked eye, and not just to atomic or subatomic systems.

It is accepted that a subatomic particle can exist in a superposition of states, a combination of possible states. According to the Copenhagen Interpretation, the superposition only settles into a definite state upon observation. This is known as collapse or measurement.

Schrödinger proposed his "cat", after a suggestion of Albert Einstein's. Schrödinger states that if a scenario existed where a cat's state of life or death could be made dependent on the state of a subatomic particle, and also isolated from any possible observation, the state of the cat itself would be a quantum superposition — according to the Copenhagen interpretation, at least.

Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility. Rather he believed the "absurd" conclusion indicated a flawed assumption.

The thought experiment serves to illustrate the strangeness of quantum mechanics and the mathematics necessary to describe quantum states.

We now read this:

Astronomers may have unwittingly hastened the end of the Universe by simply looking at it, according to a theory reported in the latest edition of New Scientist....

[C]osmologists have discovered that the Universe is still expanding.

And, they believe, a strange, yet-to-be-detected form of energy called dark energy pervades the universe, which would explain why the sum of all the visible sources of energy fall way short of what should be out there.

Dark energy, goes the thinking, is a result of the Big Bang and is accelerating the universe's expansion.

If so, the universe is not in a nice, stable zero-vacuum state but simply [in a] state that may abruptly...again - and with cataclysmic consequences.

The energy shift from the decay would destroy everything in the universe, "wiping the slate clean," says Lawrence Krauss of Case Western Reserve University in Cleveland, Ohio.

The good news is: the longer the universe survives, the better the chance that it will mature into a stable state. We are just beyond the crucial switching point, Mr. Krauss believed.

The bad news is: the quantum effect, a truly weird aspect of physics that says whenever we observe or measure something, we reset its clock.

Mr. Krauss and colleague James Dent pointed to measurements of light from supernovae in 1998 that provided the first evidence of dark energy.

These measurements might have reset the decay clock of the "false vacuum" back to zero, back before the switching point and to a time when the risk of catastrophic decay was greater than now, said Mr. Dent and Mr. Krauss.

"Incredible as it seems, our detection of the dark energy may have reduced the life expectancy of the universe," said Mr. Krauss.

"We may have snatched away the possibility of long-term survival for our universe and made it more likely it will decay."

The report says the claim is contested by other astrophysicists and adds reassuringly: "The fact that we are still here means this can't have happened yet."

And it ain't gonna happen. My money is on Schrödinger.