The fabric of the Cosmos - Brian Greene(2004)

I would be out of my depth if I even attempted a book review here.

So no. Not doing that. 

It’s a fantastic read, goes without saying.

Will share a few weird facts of the Cosmos as brought out in the book, though.

The Universe is, to say the least, not what you think it is. It is a weird place.

So we humans should feel right at home being here.

#1 Weird Fact:  Space and Time are not Immutable and Unchangeable

Let’s start with the big things first. What is Space and Time? Isn’t it immutable and unchangeable? Isn’t Space and Time the grand arena, the unchanging permanent components of the Universe where stuff happens like galaxies colliding, supernovas, Earth going around the Sun, night becoming day etc?

Isaac Newton thought so too.

In his Principia Mathematica, Newton articulated a conception of Space and Time, declaring them absolute and immutable entities that provided the universe with a rigid, unchangeable arena.

As far as Time was concerned, Newton even made the sweeping statement that he couldn’t be bothered trying to explain what Time is all about, as everyone knows what Time is.

That is deep.

But for Albert Einstein, Space and Time were not absolute and immutable.

His insight into the very special nature of ‘light’ got him thinking on the nature of Space and Time.

As a teenager, Einstein asked: What happens if you move at light speed?

What would a light wave look like if you were to chase after it at exactly light speed? Since you and the light wave would be zipping at exactly the same speed, you would be keeping perfect pace with the light. And so, the teenage Einstein concluded, from your perspective the light should appear as though it wasn’t moving. You should be able to reach out and grab a handful of motionless light just as you can scoop up a handful of newly fallen snow.

This fantastic theory sort of makes sense.

But Einstein himself, in 1905, in his Theory of Special Relativity, postulated that the speed of light is a constant, no matter what the relative motion of the observer.

So regardless of your state of motion, whether you chase a light beam, or run from it, or just stand still, the light retains its one fixed and never changing speed of about 3,00,000 Km per second.

So Light will never appear stationary. No matter how fast you move.

From this radical postulate that the speed of light is a constant, Einstein concluded that Space and Time are relative, not absolute and immutable as Newton assumed it to be.

Each of us carries our own clock, our own monitor of the passage of time.

Each clock is equally precise, yet when we move relative to one another, these clocks do not agree. They fall out of synchronization; they measure different amounts of elapsed time between two chosen events.

This postulate of Einstein - that we all carry our ‘own clocks’, was proven by the famous Cesium Clock Experiment.

In 1971, Joseph Hafele and Richard Keating flew state-of-the-art Cesium-beam atomic clocks around the world on a commercial Pan Am jet. When they compared the clocks flown on the plane with identical clocks left stationary on the ground, they found that less time had elapsed on the moving clocks. The difference was tiny—a few hundred billionths of a second—but it was precisely in accord with Einstein’s discoveries.

So what it means is that when you move, Time travels more slowly for you than for someone who is stationary.

The same is true of distance or Space. Each of us carries our own yardstick, our own monitor of distance in space. Each yardstick is equally precise, yet when we move relative to one another, these yardsticks do not agree; they measure different distances between the locations of two specified events.

If Space and Time did not behave this way, the speed of light would not be a constant. Space and Time adjust themselves in an exactly compensating manner so that observations of light’s speed yield same result, regardless of the observer’s velocity.

#2 Weird Fact: You are Moving at Light Speed

Einstein said that when you are stationary, you move at Light speed.

At 3,00,000 Km per second. But through Time.

In his theory of Special Relativity Einstein postulated the concept of ‘Movement through Time’.

Consider this:

We are used to the fact that objects can move through space.

But Einstein said that there is another kind of motion that is equally important: objects also move through Time.

Right now, the watch on your wrist and the clock on the wall are ticking away, showing that you and everything around you are relentlessly moving through time, relentlessly moving from one second to the next.

Newton thought that motion through time was totally separate from motion through space-he thought these two kinds of motion had nothing to do with each other.

But Einstein found that they are intimately linked.

In fact, the revolutionary discovery of Special Relativity is this: When you look at something like a parked car, which from your viewpoint is stationary—not moving through space, that is—all of its motion is through time. The car, its driver, the street, you, your clothes are all moving through time in perfect sync: second followed by second, ticking away uniformly. But if the car speeds away, some of its motion through time is diverted into motion through space.

The speed of the car through Time slows down, when it diverts some of its motion through time into motion through Space.

This means that the car’s progress through time slows down.

And therefore time elapses more slowly for the moving car and its driver than it elapses for you and everything else that remains stationary.

Special Relativity declares that the combined speed of any object’s motion through Space and its motion through Time is always precisely equal to the speed of light.

The maximum speed through Space is reached when all light-speed motion through time is fully diverted into light-speed motion through space—one way of understanding why it is impossible to go through space at greater than light speed.

Light, which always travels at light speed through space, is special in that it always achieves such total diversion.

Time stops when travelling at the speed of light through space. A watch worn by a particle of light would not tick at all. Light realizes the dreams of Ponce de León and the cosmetics industry: it doesn’t age.

#3 Weird Fact: Space is Warped and Curved

Why does the Earth go around the Sun? Or the moon around the Earth?

It’s because Space is curved and warped.

Not smooth and featureless as one might expect.

If you roll a marble on a smooth wooden floor, it will travel in a straight line. But if you recently had a terrible flood and the floor dried with all sorts of bumps and warps, a rolling marble will no longer travel along the same path. It will be guided this way and that by the warps and curves on the floor’s surface.

In 1915, in his Theory of General Relativity, Einstein postulated that the presence of matter or energy has an effect on Space much like the effect the flood had on the floor. Matter and energy, like the sun, cause Space to warp and curve.

And just as a marble rolling on the warped floor travels along a curved path, Einstein stated that anything moving through warped space—such as the earth moving in the vicinity of the sun—will travel along a curved trajectory.

That, according to Einstein, is how gravity exerts its influence amongst heavenly bodies and everything else in the Universe.

#4 Weird Fact: The Quantum World

If you thought the Cosmos is kinda weird, then you probably have not been introduced to the Quantum world as yet.

That’s where things get truly insane.

Einstein classified Quantum mechanics in precise scientific terms: Spooky

Consider a few bizarre facts predicted by quantum mechanics and scientifically proven:

# Non Locality

Quantum mechanics predicts that interconnections between two particles need not be local.

What this means is that something that happens here can be entwined with something that happens far away, even if nothing travels from here to that location far away. It’s called Entanglement.

Quantum connection between two particles persists even if they are on the opposite sides of the Universe.

For example, consider two people standing on opposite sides of a lake wearing sunglasses. Light from the surface of the lake reflects and photons are emitted. Quantum mechanics shows that there is a 50-50 chance that a particular photon reflected towards you from the surface of a lake will make it through your sun glasses.
When the photon hits the glass, it randomly “chooses” between reflecting back and passing through. The astounding thing is that such a photon can have a partner photon that has sped miles away in the opposite direction and yet, when confronted with the same 50-50 probability of passing through the sun glasses of the person standing on the opposite side of the lake, will somehow do whatever the initial photon does. Even though each outcome is determined randomly and even though the photons are far apart in space: if one photon passes through, so will the other.
This is the kind of nonlocality predicted by quantum mechanics.

Quantum Mechanics says that two things can be separated by an enormous amount of space and yet not have a fully independent existence. A quantum connection can unite them, making the properties of each contingent on the properties of the other.

# Probability wave of an electron

According to quantum mechanics, every probability wave of an electron extends throughout all of space, throughout the entire universe. In many circumstances, though, a particle’s probability wave quickly drops very close to zero outside some small region, indicating the overwhelming likelihood that the particle is in that region.

Nevertheless, so long as the probability wave of an electron somewhere in the Andromeda galaxy has a nonzero value, no matter how small, there is a tiny but genuine—nonzero—chance that the electron could be found there.

So what it means is that there is a probability that the single electron you just exhaled sitting in your room can be found on the dark side of the moon.

# Position and velocity of a particle

Quantum mechanics claims that the position and the velocity of a particle cannot simultaneously have definite values.

Instead, particles hover in quantum limbo, in a fuzzy, amorphous, probabilistic mixture of all possibilities; only when measured is one definite outcome selected from the many.

#5 Weird Fact: Time is Illusory

The passage of Time is illusory.

The past, present and future have already happened.

It’s like the movie reel. Each portion of the reel captures a particular scene. When you watch the movie, you have the illusion of various scenes playing out moment after moment. But that is just an illusion.

Similarly, events in the entire Universe- past, present and future have already occurred.

Or to put it differently, the past, present and future all exist simultaneously. What you experience as a flow of time is just an illusion. The Big Bang and the end of the Universe have all occurred and exist as frozen moments in time.

We intuitively ascribe this particular moment, this ‘Now’ to be same for everyone across the Universe.

For instance, if in this ‘Now’, am reading a book and someone is watching a movie in New York, and simultaneously a Volcano is erupting in Jupiter, we believe this ‘Now slice’ of Space-time should be the same for everybody.

But this view is dated.  A Newtonian way of envisioning reality.

According to Newton’s absolute space and absolute time, everyone’s freeze-frame picture of the Universe at a given moment, contains exactly the same events; everyone’s ‘Now’ is the same ‘Now’, and so everyone’s ‘Now-list’ for a given moment is identical. If someone or something is on your ‘Now-list’ for a given moment, then it is necessarily also on my ‘Now-list’ for that moment.

Most people’s intuition is still bound up with this way of thinking, but Special Relativity tells a very different story.

As already explained, Time moves slower for someone in motion as compared to someone stationary.

So there are ‘Different Now’s’ for the ones moving and those stationary. Their clocks will not match.

Observers moving relative to each other have different conceptions of what exists at a given moment, and hence they have different conceptions of reality. At everyday speeds, the angle between two observers ’Now-slices’ is minuscule; that’s why in day-to-day life we never notice a discrepancy between our definition of ‘Now’ and anybody else’s.

The author gives an example to drive this point home. A thought experiment:

Imagine that Chewie is on a planet in a galaxy far, far away—10 billion light-years from Earth—idly sitting in his living room.

Imagine further that you and Chewie are not moving relative to each other. Since you are at rest relative to each other, you and Chewie agree fully on issues of space and time: you would slice up space-time in an identical manner, and so your ‘Now-lists’ would coincide exactly.

After a little while, Chewie stands up and goes for a walk—a gentle, relaxing amble—in a direction that turns out to be directly away from you. This change in Chewie’s state of motion means that his conception of ‘Now’, his slicing up of space-time, will rotate slightly.

This tiny angular change has no noticeable effect in Chewie’s vicinity: the difference between his new ‘Now’ and that of anyone still sitting in his living room is minuscule.

But over the enormous distance of 10 billion light-years, this tiny shift in Chewie’s notion of ‘Now’ is amplified.

His ‘Now’ and your ‘Now’, which were one and the same while he was sitting still, jump apart because of his modest motion. If Chewie walks away from you at about 10 miles per hour, the events on earth that belong on his new ‘Now-list’ are events that happened about 150 years ago, according to you!

According to his conception of ‘Now’—a conception that is every bit as valid as yours and that up until a moment ago agreed fully with yours—you have not yet been born!

If he moved towards you at the same speed, the angular shift would be opposite, so that his ‘Now’ would coincide with what you would call 150 years in the future! Now, according to his ‘Now’, you are no longer be a part of this world.

And if, instead of just walking, Chewie hopped into the Millennium Falcon travelling at 1,000 miles per hour (less than the speed of a Concorde aircraft), his ‘Now’ would include events on Earth that from your perspective took place 15,000 years ago or 15,000 years in the future, depending on whether he flew away or towards you.

So: if you buy the notion that reality consists of the things in your freeze-frame mental image right now, and if you agree that your ‘Now’ is no more valid than the ‘Now’ of someone located far away in space who can move freely, then reality encompasses all of the events in space-time.

If we can visualize ‘all of Space’ as really being out there, as really existing, we could also visualize ‘all of time’ as really being out there, as really existing, too.

Past, present and future certainly appear to be distinct entities. But, as Einstein once said, “The distinction between past, present and future is only an illusion, however persistent.”

The only thing that’s real is the whole of space-time.

In this way of thinking, events, regardless of when they happen from any particular perspective, just are. They all exist. They eternally occupy their particular point in space-time.

There is no flow. If you were having a great time at the stroke of midnight on New Year’s Eve, 1999, you still are, since that is just one immutable location in space-time.

This book is a great read for the layman.

And the weirdness quotient of the Universe just increases when the author talks of Multi-verse, hidden dimensions, String Theory...

Can’t recommend this book enough.