Why does time runs always forward not backward ?!!


Why is it you can break an egg, but not make the pieces spring back together again? To find out, we have to go back to the birth of the universe!!

Wall of Clocks in a Store. Image shot 2007. Exact date unknown.


Why don’t things happen in reverse all the time?

Sounds ridiculous — but why? Why, exactly, is it impossible to un-break an egg?

It isn’t. There’s no fundamental law of nature that prevents us from un-breaking eggs. In fact, physics says that any event in our day-to-day lives could happen in reverse, at any time. So why can’t we un-break eggs, or un-burn matches, or even un-sprain an ankle? Why don’t things happen in reverse all the time? Why does the future look different from the past at all?

It sounds like a simple question. But to answer it, we’ve got to go back to the birth of the universe, down to the atomic realm, and out to the frontiers of physics.

The first person to seriously tackle this problem was an Austrian physicist named Ludwig Boltzmann, who lived in the late 19th century. At this time, many ideas that are now known to be true were still up for debate. In particular, physicists were not convinced – as they are today – that everything is made up of tiny particles called atoms. The idea of atoms, according to many physicists, was simply impossible to test.

He was ostracised by the physics community for his ideas

Boltzmann was convinced that atoms really did exist. So he set out to use this idea to explain all sorts of everyday stuff, such as the glow of a fire, how our lungs work, and why blowing on tea cools it down. He thought he could make sense of all these things using the concept of atoms.

Newton threw himself into the study of physics.

You might mix up east and west, but you would not mix up yesterday and tomorrow

He came up with three laws of motion, including the famous maxim that every action has an equal and opposite reaction. He also devised an explanation of how gravity works.

Boltzmann’s take on entropy explains!!

The future looks different from the past simply because entropy increases

Crushing egg with egg yolk splash

Boltzmann’s take on entropy explains why it always increases. That in turn suggests why we always experience time moving forwards. If the universe as a whole moves from low entropy to high entropy, then we should never see events go in reverse.

The future looks different from the past simply because entropy increases

We won’t see eggs un-break, because there are lots of ways to arrange the pieces of an egg, and nearly all of them lead to a broken egg rather than an intact one. Similarly, ice won’t un-melt, matches won’t un-burn, and ankles won’t un-sprain.

Boltzmann’s definition of entropy even explains why we can remember the past but not the future. Imagine the opposite: that you have a memory of an event, then the event happens, and then the memory disappears. The odds of that happening to your brain are very low.

According to Boltzmann, the future looks different from the past simply because entropy increases. But his pesky opponents pointed out a flaw in his reasoning.

Why is there an arrow of time at all?


The flaw in Boltzmann’s reasoning disappears.

Within a decade, physicists accepted his ideas

We discovered that it had a beginning.

The universe began as an infinitely tiny speck, which exploded

In Boltzmann’s time, most physicists believed that the universe was eternal – it had always existed. But in the 1920s, astronomers discovered that galaxies are flying apart. The universe, they realised, is expanding. That means everything was once close together.

Our best theories of physics can’t actually handle the Big Bang

If that’s true, the early universe only looks like it has low entropy because we can’t see the bigger picture. The same would be true for the arrow of time.

Nobody has managed to come up with a theory of everything

So if something is both very small and very heavy, like the universe during the Big Bang, physicists get a bit stuck. To describe the early universe!!

the laws of physics are different in different universes.

String theory might not help explain the arrow of time

This all sounds quite outlandish. Nevertheless, most particle physicists see string theory as our best hope for a theory of everything.

Theory that incorporate the arrow of time at a fundamental level.

Time isn’t really an illusion

Cortês and Smolin suggest that the universe is made up of a series of entirely unique events, never repeating itself.

we’ve got it?

Our best hope lies with the largest machine in human history

We could test it using something very small and very dense. But we can’t go back in time to the Big Bang, and regardless of what a recent blockbuster movie suggested!!


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