Why Entropy Happens

In the beginning, there was order, a very hot singularity, but as time progressed the universe expanded and cooled--and became more disorderly. Scientists predict a "big freeze." It's all due to entropy. As you read this blog, entropy continues. Why? That's what we will explore below. First, let's define the variables we will use:

We begin with the partition function, which has the Boltzmann factor, an exponent with a thermodynamic beta power over the base e:

If we want to determine the probabilities of the energies in a system, we make sure the probabilities add up to 1, so we normalize the partition function by dividing it by itself (Z):

However, if we want to model the universe's evolution, we need to make a slight change to the partition function. Instead of using the thermodynamic beta, we use its reciprocal. We also change the i index to a time (t) index:

Also, we want the universe's total energy to be conserved. We know dark energy is increasing and radiation energy is decreasing, so we put together an energy-conservation equation:

At equation 5, notice how an increase in the universe's volume (V) reduces the radiation energy (Er) but increases the dark energy (pV). Multiply the two energies, add a little dark and baryonic matter, and take the square root and we get a constant energy (E).

We define temperature as follows:

As volume (V) increases, the universe's temperature decreases. Equation 7 below gives us the probability of the temperature at a given time t:

A high temperature has a low probability. A low temperature has a high probability. So there is a high probability the universe's temperature will continue to decrease, and a low probability the temperature will increase. Thus, an expanding universe has a higher probability.

Now, let's take a look at entropy. We define it as follows:

We see that entropy increases as temperature decreases--so it has the same probability as temperature:

So why does entropy happen? Greater entropy has a higher probability than lower entropy. We can also say that reverse entropy is possible but less probable. A good example is the one Tyson discussed in the above video. There are pockets of order caused by star energy, so life is possible.

What We Didn't Know About Time Travel Could Surprise Us

According to Hollywood and even some scientists, going back in time means seeing history repeat itself. We worry that if we interfere with the past, the future might unfold differently, unexpectedly and even disastrously.

Imagine Hitler winning World War II or your parents never getting together, so you are never born--all because you spit on the sidewalk in the year 1933, which set off a chain of events that changed the future.

What I described above is rather nonsensical if we take entropy into account (s=change in entropy; k=Boltzmann's constant; ln is the natural log; omega=number of ways particles can arrange themselves):

If our most common belief about time travel is correct, then entropy would have to shut down, so history could repeat itself exactly as before. But then we might ask, why should history repeat itself exactly as before (assuming we don't interfere)?

To satisfy our curiosity, what would happen if entropy remains intact during our time-travel excursion? Imagine a universe with one particle in it. It can go either right or left as it passes through time. The probability (p) is 0.5 for each move just like a coin toss:

The particle makes three moves, following a path that is one out of eight possible paths. The path it takes is outlined in red:

The red path represents its history. The entropy starts with a single possibility and evolves into eight possible paths.

Now let's find a wormhole and travel back in time to the particle's starting point and watch its history unfold again:

Oh wow! History failed to repeat itself. We didn't interfere. We were good. We watched from afar ensconced in our time-travel VW bug. Relax, it's not our fault. Entropy was just doing its job. There was only a one-in-eight chance history would repeat itself and a seven-out-of-eight chance it would not. I mentioned earlier that we didn't interfere, but we did go back in time and that in itself is a kind of interference that could possibly alter history.

OK, so maybe going through a wormhole is not the best way to go back in time. Sometimes going back in time is described as a movie going in reverse. If we flip a cosmic projector switch and make the particle go back in time, it should follow the red path back to its starting point:

Oh no! What happened? The particle didn't behave like a backward-running film. It took a different path back. And why not? It can go left or right at any node along the path. To get the equivalent of a backward-running flick, the particle's probability distribution would have to exit the theater.

Backward time travel, as we imagine it, requires an entropy of zero: one path the particle can take and not the usual eight. If we treat the particle's present as a single starting point, the change in entropy would evolve as follows:

Just for fun, let's assume the particle's probabilities of going left or right stay intact when time is reversed. Its past would most likely be different than expected. The past it remembers is only one of eight possible paths to its present time.

Now apply what we've learned to your past. Imagine the implications! You go back in time, but you see a different past than you remember. You think to yourself, "This is not my life!" Your past self looks different, like a brother or sister--because you may not be the same person or sex! A different sperm cell beat all the others to your mother's egg. Your parents still gave you the same name (assuming your sex is the same) but you're watching the life of a different person who took your place because you just had to try out that bloody time machine!

Since your past is messed up anyway, you might as well interfere with it, i.e., take advantage. You read in a history book that the racehorse, Fools-errand, won the Kentucky Derby, so you decide to place a bet, but don't place that bet--it's a fool's errand.

For more on this topic, click here or here or here.

Untangling the Quantum Entanglement Probability

According to the video above, Bell's Inequality theorem shows that two fictional characters, Bob and Alice should get the same results more than 33% of the time. The actual probability of them getting the same outcome is 25%. But why 25%?

Since the particles Bob and Alice possess are entangled, and since Bob and Alice are not, it stands to reason that the probability of Bob and Alice being in sync would be less than expected.

Suppose Bob and Alice each randomly choose one of two polarizers: up or down. They compare notes hoping for a match. Next, they each send one of the entangled particles through their respective polarizers. Each check the spin of his/her particle to see if it is up or down. They compare notes again, hoping for another match.

If the particles weren't entangled the experiment would yield these possible outcomes:

The above outcomes show that Bob and Alice are in sync 50% of the time (which is greater than 33%). Four out of eight outcomes show their particles have the same spin or Alice and Bob picked the same polarizer.

Now here are the possible outcomes if the particles are entangled with opposite spin:

As you can see the probability falls from 50%. Alice's particle is no longer independent of Bob's. If Bob's particle's spin is up, Alice's is down, and vice versa. There are no longer up-up or down-down outcomes.

Probabilities, Euler's Identity and Super-complex Numbers

Today we are going to examine how super-complex numbers fit in with Euler's identity and probability amplitudes. If you are not familiar with super-complex numbers, read my post entitled: "Introducing Super Complex Numbers."

Euler's identity is as follows:

It has a cosine and one isine or imaginary number. It can be used to model a right triangle:

Or a propagating wave:

Here is the super-complex number version of Euler's identity:

The exponent has i sub-n and theta sub-n. This tells us we will take the cosine of angle theta, and the isine-thetas from 1 to n. In the example below, n = 3.

The super-complex Euler identity is useful if you are working with one cosine and multiple triangles that share the same cosine. Take the exponent i sub-n, theta sub-n; it shows precisely how many isines/triangles are involved. The super-complex Euler identity is a real time saver. Instead of writing a big long string of trig functions we can write one simple exponent.

Since it can represent multiple triangles, it can be used to represent a wing design for a stealth aircraft:

OK, so that wasn't really a stealth aircraft--just more triangles, but you get the idea. Below are multiple waves propagating through space that are modeled by the super-complex Euler ID:

We know that if we multiply Euler's identity with its complex conjugate we get 1. We can also take the inner products of cosine and isine to get probabilities, but notice we are stuck with just two probabilities:

Using the super-complex Euler ID, is it possible to have as many probabilities as we like--and they all add up to one? To answer this question we need to derive the super-complex Euler ID. Start with the normal Euler ID, then split up the isin(theta) into smaller parts. Each part shall have a coefficient of epsilon:

If we examine a unit circle diagram and some trig relations, we discover that each epsilon sub-j isin(theta) equals isin(theta sub-j). We make a substitution:

If we equate i with each i sub-j and i sub-k, we assume the product of any two indexed i's is -1. Unfortunately this will give us non-zero cross product terms.

Let's check to see if the cross product of two arbitrary indexed i's really do give us -1 and not 0. Take the sum of two arbitrary terms and multiply it by its super-complex conjugate. That will give us a real number we label b^2. Like the isine of Euler's ID, we split b into smaller parts. Call those parts c and d.

The last equation above confirms the product of any two indexed i's equals -1. The great thing about Euler's ID is the square of its absolute value yields the same result as a dot product. We want the super-complex Euler's ID to behave the same way--no non-zero cross products! So here's what we do:

At the second equation above, we assume there are no non-zero cross product terms on the right side; however, without the extra cross-product terms, the left side is greater than the right side. We cure this by increasing the value of the isines. We then throw in unit vectors (ej). We now have a multiplication that behaves like an inner or dot product. We make some further refinements below:

Note how each indexed i is converted to an indexed mu, which behaves like a unit vector, giving the result we want:

Each squared sine can represent a probability and the total is 1.

As you can see, the super-complex version of Euler's identity has a great deal more flexibility than the ordinary Euler's identity. It allows us to model complex systems and probability amplitudes with just one simple exponent expression.

How Uncertainty is the Root of All Certainty

If you roll a pair of dice, you never know what you will get. You might get anything from snake eyes to twelve. But what happens when you roll a trillion pairs of dice all at once? Strangely enough, you get seven-trillion or a number very close to that figure when you add up all those dice. The uncertainty has become a certainty.

When you calculate the average dice throw, the number you always get is seven. Seven is the mean number, and two and twelve are the extreme numbers. Even if you were to eliminate all the numbers between two and twelve, you would still have an average of seven.

(2 + 12)/2=7

There is an old theorem in quantum mechanics (Ehrenfest theorem) that says that all our laws of physics that give us certain results are rooted in uncertainty. The “certain result” is called the expectation value. You calculate the expectation value by simply adding up and taking the average of all the uncertain results.

At small scales, matter behaves in very strange and unexpected ways, but at large scales, matter behaves as we expect: it follows the laws of Newtonian physics. It behaves much like a pair of dice on the quantum scale, and behaves like a trillion pairs of dice on our old, familiar scale.