Can't travel back in time

The urge to feel loved for the first time or to correct the past is one of the reasons why we dream of going back in time. But scientists claim it is impossible.

There have been dozens of travel perspectives about the past given by theorists, "but most of them, if examined carefully, only glide at the edge of the physics industry that we can understand. big scientists think that most of that scenario could be excluded, "said Brian Greene, author of bestseller ' The Elegant Universe ', expert on string theory, a physicist at Columbia University, for know.

Wednesday afternoon

Astronomer Charles Liu
(Photo: LiveScience)

In physics, time is described as one dimension, like length, width and height. When you go from your home to the grocery store, you have moved in a direction in space, creating translation in all those dimensions - long, wide and tall. But you move forward even in the afternoon time - Wednesday afternoon.

"Space and time twist together in the form of a 4-dimensional frame called space-time," said Charles Liu, an astrophysicist at City University, New York.

Space-time, Liu explained, could be viewed as a 4-way rubber pad. When an object has mass - you, me or any object, a planet or some star - is placed on that 4-dimensional pad, it will cause the pad to sag.

This hammock is a deformed image of space-time to suit that heavy object. The space-time indentation makes objects move on a curve and the curvature of space is what we call gravity.

Mathematically one can move forward or backward in three dimensions, but time does not have this omnidirectional freedom.

"In 4-dimensional space-time, you can only move forward of time, ie the future , " Liu said.

Past tunnels?

(Photo: Astrosciences)

There exist some hypotheses about traveling through time. The most elaborate hypothesis concerns the wormhole - a theoretical tunnel connecting the two space-time regions. These two regions can be two completely different universes or two parts of a universe. Material can pass through one of the two mouths to reach the destination on the other side.

"Wormhole is the future, wormhole is the past" , Michio Kaku, author of " Hyperspace " and " Parallel Worlds ", and a physicist at City University, New York, said. "But we have to be very careful. The amount of gas needed to operate a time machine goes far beyond what we can collect with current technology."

To create a hole in the space-time membrane, Kaku explains, needing a star's energy or negative energy, a strange entity with smaller energy.

Cosmic strings

Physicist Michio Kaku (Photo: LiveScience)

Another familiar hypothesis for those who prefer to travel back in time involves the so-called cosmic string - that is, narrow energy tubes spread along the entire length of the expanding universe. These ultra-narrow regions, left over from the primitive time, are expected to contain an enormous amount of material and thus can bend space-time around them.

The cosmic strings are either endless or curled into rings, without end, J.Richard Gott, author of "Time Travel in Einstein's Universe" and an astronomer at Princeton University, said.

The contact of such two wires is parallel - Gott says - will bend extremely space-time and in some special situation may make time travel theoretically feasible.

But: "it's a project that only a super civilization can do," Gott said. "It is beyond our ability. We are a civilization that has not even controlled the energy of the earth itself."

Can not now

Mathematically, you can certainly say that something is going back in time, Liu said."But will not be me and you".

"Don't expect a young inventor to press a press tomorrow that he or she invented a time machine. Because it needs a much more advanced technology than anything we can. gathered , " Kaku said.

Currently, the only part of traveling in 4-dimensional space is that we are moving toward the future with each passing second. So for those who want to see the earth after 1 million years, scientists have had good news.

"Build a spacecraft. Fly at a speed near the speed of light for a long time - what I can calculate. Then go back to earth and when you step out of the spacecraft, you will age about 1 year while the earth has gone through a million years, in that way, you have come to its future , " Greene said.

(Photo: LiveScience)

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