They’ve just arrived after epic journey to Earth, and offer surprising tale about structure of universe
Seven billion years ago, three cosmic travelers set out together on an epic journey to Earth. They just arrived, and the trio has a surprising tale to tell about the structure of the universe. Their story could overturn decades of work by theoretical physicists.
But first, an introduction: Scientists have long wondered about the nature of space and time. Albert Einstein envisioned the two concepts as an interwoven fabric that extends smoothly and continuously throughout the universe, warping under the weight of the matter it contains. The smoothness of this stretchy “space-time” fabric means that no matter how closely one inspects it, no underlying structure emerges. The fabric is completely pure even at infinitesimal scales.
The snag in this picture of a space-time fabric is that it doesn’t jive with quantum mechanics, the set of laws describing the bizarre behavior of subatomic particles. To explain gravitational interactions between planets and stars, Einstein’s theory works beautifully; but try to describe quarks or electrons zipping about on a fabric with no elemental structure, and the equations turn to nonsense.
Modern “theories of everything” try to reconcile Einstein’s big picture view of the universe, built of space-time, with the small-scale picture of the universe described by quantum mechanics. Most of these theories, collectively called “quantum gravity,” posit that space-time must not be smooth after all, but must instead be comprised of discrete, invisibly small building blocks – sort of like 3-D pixels, or what scientists have dubbed a “foam.”
But real or not, such space-time pixels seemed to be permanently out of human reach. For reasons having to do with the uncertainty that exists in the locations of particles, theories suggest the pixels should measure the size of the “Planck length,” or about a billionth of a billionth of the diameter of an electron. With the key evidence for quantum gravity buried at such an inaccessible scale, physicists were at a loss for how to confirm or refute their ideas.
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