... But it's the universe, not the Earth, that might be flat – a 2-dimensional hologram, according to an international team of researchers.
Holograms might be most familiar as the colorful 3-D images used as security measures on some credit cards and currencies. But of course, they're not really 3-dimensional, are they? They contain all the information necessary for our eyes to perceive them that way, but the pictures are actually printed on a 2-D surface. A new calculation, published last Monday in Physical Review Letters, says that models describing our early universe similarly have now been shown to agree with recent observations just as well as standard 3-D models do.
... The sticking point is gravity. Ever since Einstein's General Theory of Relativity described the force that keeps our feet on the ground as a consequence of the shape of space, it's been giving physicists headaches.
Other forces, including electromagnetism, can be explained in terms of particles. Magnets may seem to be magically tugging on each other from a distance, but at some level they're swapping photons. Gravity has vigorously resisted this kind of particle-level description, giving rise to exotic theories of quantum gravity such as string theory.
One proposed bridge between these odd theories of gravity and more established quantum theories of particles accomplishes "lots of wonderful things," writes particle physicist Raphael Bousso of the University of California at Berkeley in an email to The Christian Science Monitor.
Two months ago in Dec 2016, astrophysicist Paul Sutter authored this article entitled "The Universe Is Flat — Now What?"
... The universe is flat. But there's a lot of subtlety packed into that innocent-looking statement. What does it mean for a 3D object to be "flat"? How do we measure the shape of the universe anyway? Since the universe is flat, is that…it? Is there anything else interesting to say?
Oh yes, there is.