Access to the past would open all sorts of new possibilities of more than travel.
By Charles Q. Choi, ISNS Contributor via Inside Science
(ISNS) — Time travel is often a way to change history in science fiction such as “Back to the Future” and “Looper.” Now researchers suggest a certain kind of time machine could also possess another powerful capability — cloning perfect copies of anything.
However, scientists noted the way these findings violate what is currently known about quantum physics might instead mean such time machines are not possible.
We are all time travelers in that we all move forward in time. However, scientists have suggested it might be possible to move back in time by manipulating the fabric of space and time in our cosmos. All mass distorts space-time, causing the experience of gravity, a bit like how a ball sitting on a rubber sheet would make nearby balls on the sheet roll toward it. Physicists have proposed time machines that could bend the fabric of space and time so much that timelines actually turn back on themselves, forming loops technically known as “closed timelike curves.”
These space-time warps can develop because of wormholes — tunnels that can in theory allow travel anywhere in space and time, or even into another universe. Wormholes are allowed by Einstein’s general theory of relativity, although whether they are practically possible is another matter.
A key limitation of this kind of time machine would be that any traveler using it cannot go back to a time before the device was built. It only permits travel from the future back to any point in time after the machine was constructed.
Scientists have for decades explored what closed timelike curves are capable of if they are possible.
One complication they would encounter is the no-cloning theorem in quantum physics, which basically forbids the creation of identical copies of any particle one does not know everything about to begin with.
In classical physics, one can generate a perfect copy of anything by finding out every detail about it and arranging the same components in the same order. However, in the bizarre world of quantum physics — the best description so far of how reality behaves on its most fundamental levels — one cannot perfectly measure every detail of an object at once. This is related to Heisenberg’s uncertainty principle, which notes that one can perfectly measure either the position or the momentum of a particle, but not both with unlimited accuracy.
Nearly 25 years ago, theoretical physicist David Deutsch at the University of Oxford in England suggested closed timelike curves might actually violate the no-cloning theorem, allowing perfect copies to be constructed of anything. Now scientists reveal this might be true in findings detailed in the Nov. 8 issue of the journal Physical Review Letters.
To understand this research, imagine one builds a time machine in the year 2000. One could place a letter into the device in the year 3000 and pick it up within this box in 2000 or any year between then and 3000. From the perspective of the letter, it goes inside this time machine into one mouth of a wormhole in the future and comes out the other mouth of the wormhole in the past.
However, theoretical physicist Mark Wilde at Louisiana State University, in Baton Rouge, and his colleagues found this scenario may be more complex than previously thought. Instead of the time machine containing just one wormhole, it could possess many wormholes, each at some point in time between the future and the moment of its creation. A letter entering the box in 3000 might exit from a wormhole in 2999, instantaneously go back into that wormhole and emerge in 2998, and so on.
“It’s like there are 1,000 different particles emerging from all the wormholes, but in fact they’re all the same particle you sent in the beginning,” Wilde said. “You just have all these temporary copies emerging from and going back into these wormholes.”
Members of the Flat Earth Society claim to believe the Earth is flat. Walking around on the planet’s surface, it looks andfeelsflat, so they deem all evidence to the contrary, such as satellite photos of Earth as a sphere, to be fabrications of a “round Earth conspiracy” orchestrated by NASA and other government agencies.
The belief that the Earth is flat has been described as the ultimate conspiracy theory. According to the Flat Earth Society’s leadership, its ranks have grown by 200 people (mostly Americans and Britons) per year since 2009. Judging by the exhaustive effort flat-earthers have invested in fleshing out the theory on their website, as well as the staunch defenses of their views they offer in media interviews and on Twitter, it would seem that these people genuinely believe the Earth is flat.
But in the 21st century, can they be serious? And if so, how is this psychologically possible?
Through a flat-earther’s eyes
First, a brief tour of the worldview of a flat-earther: While writing off buckets of concrete evidence that Earth is spherical, they readily accept a laundry list of propositions that some would call ludicrous. The leading flat-earther theory holds that Earth is a disc with the Arctic Circle in the center and Antarctica, a 150-foot-tall wall of ice, around the rim. NASA employees, they say, guard this ice wall to prevent people from climbing over and falling off the disc. Earth’s day and night cycle is explained by positing that the sun and moon are spheres measuring 32 miles (51 kilometers) that move in circles 3,000 miles (4,828 km) above the plane of the Earth. (Stars, they say, move in a plane 3,100 miles up.) Like spotlights, these celestial spheres illuminate different portions of the planet in a 24-hour cycle. Flat-earthers believe there must also be an invisible “antimoon” that obscures the moon during lunar eclipses.
Furthermore, Earth’s gravity is an illusion, they say. Objects do not accelerate downward; instead, the disc of Earth accelerates upward at 32 feet per second squared (9.8 meters per second squared), driven up by a mysterious force called dark energy. Currently, there is disagreement among flat-earthers about whether or not Einstein’s theory of relativity permits Earth to accelerate upward indefinitely without the planet eventually surpassing the speed of light. (Einstein’s laws apparently still hold in this alternate version of reality.)
As for what lies underneath the disc of Earth, this is unknown, but most flat-earthers believe it is composed of “rocks.” [Religion and Science: 6 Visions of Earth’s Core]
Then, there’s the conspiracy theory: Flat-earthers believe photos of the globe are photoshopped; GPS devices are rigged to make airplane pilots think they are flying in straight lines around a sphere when they are actually flying in circles above a disc. The motive for world governments’ concealment of the true shape of the Earth has not been ascertained, but flat-earthers believe it is probably financial. “In a nutshell, it would logically cost much less to fake a space program than to actually have one, so those in on the Conspiracy profit from the funding NASA and other space agencies receive from the government,” the flat-earther website’s FAQ page explains.
It’s no joke