Wednesday, July 01, 2015

An Alternative Model of the Software Universe

In The Software Universe as an Implementation of the Mathematical Universe Hypothesis I explained that when I first began to work on softwarephysics my intent was to simply come up with a set of effective theories to help explain how the Software Universe seemed to behave and that I did not have the luxury of trying to shoot for an all encompassing explanation of what the Software Universe was all about. In the MUH - the Mathematical Universe Hypothesis – both the Software Universe and our physical Universe are simply timeless mathematical structures in a Platonic sense that have always existed because mathematical structures are not time-bound – they are eternal truths outside of time. For example, for the case of the Software Universe, Max Tegmark remarked in Our Mathematical Universe: My Quest for the Ultimate Nature of Reality (2014) that it did not really matter if the software was actually running on a computer or not because the output of the software was determined by the software itself and the input that it was to work upon. The same thing is essentially true for the infinite number of other universes that can be generated from the Level IV multiverse of mathematical structures. They also do not have the element of time because they are generated from timeless mathematical structures. This is a bit bothersome because as sentient beings we definitely sense the passage of time. We all seem to live in the present moment and can remember the past and anticipate the future. But others claim that this sensation of the flow of time is a deception played upon us by our senses, and those “others” are not just philosophers dallying around in metaphysics; most physicists would make the same claim that the apparent flow of time is an illusion too.

All of this made me feel that it was time to reread a couple of good books: Programming the Universe: A Quantum Computer Scientist Takes on the Cosmos (2006) by Seth Lloyd and The Trouble with Physics (2006) and Time Reborn – From the Crisis in Physics to the Future of the Universe (2013) by Lee Smolin to help clarify the situation. I like to periodically reread good books because I find that each reading seems to bring with it additional meaning. This is not just because repetition inherently brings with it better understanding, but also because in the interval between readings, hopefully I will have advanced my personal model of what’s it all about, and it doing so, become more receptive to some of the subtleties of the books I am rereading.

In Programming the Universe Seth Lloyd contends that our Universe is a quantum mechanical Computational Universe that has been calculating how to behave from the very beginning. Seth Lloyd came to this conclusion as MIT’s sole quantum mechanical engineer working on building practical quantum computers. During the course of his research Seth Lloyd has learned how to talk to atoms in a quantum mechanical way. Through intimate dealings with these atoms, he found that the atoms were constantly flipping quantum mechanical states in a controlled manner prescribed by quantum mechanics. Since a computer is simply a large number of switches that operate in a controlled manner, our Universe can therefore be thought of as a Computational Universe, and therefore, must necessarily be capable of computation. In fact, our current quest to build quantum computers can simply be viewed as an attempt to domesticate this natural tendency for our Universe to compute in a quantum mechanical manner. Seth Lloyd calculates that our section of the Computational Universe which is defined by our current cosmic horizon and consists of all quantum particles out to a distance of 46 billion light years, has performed about 10122 operations on 1092 bits over the past 13.8 billion years. This domestication of the quantum mechanical behavior of our Computational Universe has already led to the construction of many trillions of classical computers already. So Seth Lloyd’s Computational Universe model is very similar to Max Tegmark’s CUH – the Computable Universe Hypothesis – which is a subset of his MUH. The chief difference is that the Computational Universe model has the element of time, while the CUH model does not.

A Matter of Time
So it all boils down to the age-old question of whether time is real or not. That might sound like a silly question, but it has been bothering physicists and philosophers from the very beginning. But even that statement makes the assumption that time actually is real to begin with, and highlights the difficulty of the problem. Lee Smolin takes up this difficult problem of time in Time Reborn, and proposes that physics and cosmology must go back to Newton’s original contention that there is an absolute time that is a fundamental aspect of objective reality in order to make progress. In his Principia (1687), Newton defined an absolute time independent of observers as:

Absolute, true and mathematical time, of itself, and from its own nature flows equably without regard to anything external, and by another name is called duration: relative, apparent and common time, is some sensible and external (whether accurate or unequable) measure of duration by the means of motion, which is commonly used instead of true time ...

In Part 1 of Time Reborn, Lee Smolin explains how physics slowly expelled this concept of an absolute time from its current worldview. It all began with Galileo. Galileo observed that a thrown ball moved in a parabolic arc rather than in straight lines as Aristotle had contended. According to Aristotle a thrown ball moved in a straight line until it ran out of impetus, and then it fell to the earth in a straight line. The ball fell to the earth because it was in the ball’s nature to be at rest on the ground. Obviously, Aristotle must never have thrown a ball during his entire life!

Figure 1 – According to Aristotle a thrown ball went in a straight line until it ran out of impetus and then it fell to the ground in a straight line.

Even so, Aristotle’s thoughts carried the day for more than a thousand years.

Figure 2 – The above figure demonstrates that bad theories can often lead to adverse military results. Granted, Aristotle’s theory may have predicted that you should aim your cannon at 450 for maximum range, but it would not be of much use for aiming anti-aircraft shells.

Figure 3 – Galileo maintained that a thrown ball moved in a parabolic arc and not in straight lines.

Figure 4 – A parabola can be obtained by slicing a cone at an angle.

Figure 5 – A parabola is also defined as the set of points that are equal distant from a point called the Focus and a straight line called the directrix.

Figure 6 – A parabola can also be defined by a mathematical equation.

Next came the Newtonian mechanics to be found in Newton’s Principia (1687) which laid down Newton’s three laws of motion and allowed one to easily calculate the equation of the parabolic arc of a thrown ball given the initial speed and angle of the throw. Since Newton’s laws of motion are deterministic, meaning that given the ball’s initial conditions of speed and angle, the ball always follows the same exact path in space and time, it is possible to graph the thrown ball moving through space and time.

Figure 7 – A thrown ball always follows the same exact path through space and time that are defined by Newton’s laws of motion and the initial conditions of the thrown ball. In the figure above, the ball and the bullet start out at the same location X = 0 and hit the ground later at the very same spot along the X-axis that represents distance. Notice that the bullet hits the ground in much less time t than does the ball. Also note that the slower ball must also rise to a much higher height Z than does the bullet. So the fast bullet has a much flatter trajectory than does the slower ball which is lobbed to the same spot.

And since Newton’s laws of motion are reversible in time that means we could easily run time backwards and have the thrown ball repeat its parabolic path through space and time in reverse. This was the beginning of the Block Universe model of the Universe in physics. Lee Smolin calls this the Newtonian paradigm. What we do in physics is to try to isolate a system as much as possible from the rest of the Universe so that the effects upon the subsystem are reduced as much as possible. Lee Smolin calls this doing “physics in a box”. For example, we must throw our ball in a vacuum for it to really follow a parabolic path as much as possible. Then given deterministic laws and initial conditions, we can predict how the subsystem will behave moving into the future as well as into the past. Notice that in this worldview the concept of time does not play much of a role because the deterministic laws are timeless mathematical structures and the initial conditions are set for one particular time that then determine the position of the ball for all future times and for all times in the past as well. In such a model, there is no point in worrying about the future because it is all a “done deal” from the onset, and there is no free will even to let you choose to worry or not. Everything just “is”.

The Block Universe model obtained a huge boost from Albert Einstein in 1905 with his special theory of relativity. That is because Einstein was able to eliminate Newton’s concept of absolute time from his new theory. Granted, people had been debating Newton’s concept of an absolute space all along, but they had not been debating the concept of absolute time until Einstein came along. The relativists, like Galileo and Newton’s archenemy Gottfried Leibniz, had argued all along that since all spatial measurements were purely relative in nature that absolute space did not exist, and that was why the effects of absolute space could not be observed. This was based upon Galileo’s observation that you could not tell if you were moving or at rest when in the hold of a ship on a calm sea. No matter what experiment you might perform, you always got the very same result when the ship was moving forward at great speed or when it was standing still at the dock. That is why you can easily pour those little bottles of gin into a glass while traveling at 600 mph in a jet airliner. But Newton suggested that absolute space really was real because objects obviously behaved differently when you were accelerating. That is why it is not wise to try to pour those little bottles of gin while an airplane is accelerating during takeoff. The odds are that you will spill some of the gin because the gin will not pour straight while accelerating. Newton explained that things behaved differently when you were accelerating because you were accelerating relative to absolute space. He demonstrated this idea with his famous bucket experiment. Take a bucket of water that is at rest with respect to absolute space. The water will have a flat surface to begin with. Then start to spin the bucket and water relative to absolute space. At first the water will remain at rest with respect to absolute space and will remain flat in the bucket. But as the water picks up rotational motion from the bucket, it will soon begin to form a concave surface because now the water is rotating (accelerating) relative to absolute space. So absolute space must exist after all.

Figure 8 – Newton maintained that even though Galileo’s principle of relativity prevented experiments from revealing absolute space for reference frames that were not accelerating, you could still observe the effects of absolute space by spinning a bucket of water.

The way Einstein got rid of the concept of an absolute space was by getting rid of absolute space and absolute time simultaneously with his new theory. Einstein simply took Galileo’s principle of relativity and extended it to electromagnetic experiments as well. In 1820 Hans Christian Oersted discovered that when an electrical current flowed in a wire it produced a magnetic field that resulted from the electrical charges moving in the wire. So now we had a handy way of telling if something was standing still or moving. All you had to do was observe an electrically charged object. If it gave off a magnetic field, then you knew it was moving; if it did not give off a magnetic field, then you knew it was standing still. So Newton was “right” and Galileo was “wrong”, an observer could use electromagnetic experiments to tell if he was standing still or moving relative to absolute space. There was just one problem, the idea did not work. In 1901, Trouton and Noble conducted just such an experiment using a suspended charged capacitor. They tried to observe the magnetic field that should have been given off by the suspended charged capacitor as it moved through absolute space on board the Earth, as the Earth orbited the Sun. But they did not find any! In 1905, Einstein published On the Electrodynamics of Moving Bodies in which he proposed that Galileo was right after all. In this paper, Einstein proposed that you really could not conduct any experiment, including electromagnetic experiments that would reveal if you were moving or standing still relative to an absolute space, because there was no such thing as an absolute space. All motion was relative to other objects just as Galileo had proposed from the start.

In order for this to be true, Einstein had to raise two conjectures to the level of postulates:

1. The laws of physics are the same for all observers, even for observers moving relative to each other at constant speeds in straight lines.

2. The speed of light is the same for all observers, even for observers moving relative to each other at constant speeds in straight lines.

If the above two postulates were not true, you could easily tell if you were moving or standing still relative to an absolute space. All you would have to do is measure the speed of light in different directions, and if it were not the same in all directions, then you would know that you were moving relative to an absolute space. So that got rid of absolute space, but the above two postulates also caused a problem for absolute time as well because they greatly affected simultaneous events that were separated in space. This is best explained by the two animations at:

In the first animation, the Einstein on the moving platform observes two photons arriving at the same time and concludes that both photons were emitted at the same time. In the second animation, the Einstein on the ground agrees that both photons hit the Einstein on the platform at the same time too, but concludes that photon A was emitted before photon B. Note that both Einstein’s can claim to be standing still because neither one can detect any motion with experiments they perform because neither one is accelerating. What the special theory of relativity did for the Block Universe model of Figure 7 was to replace the concepts of absolute space and absolute time with the concept of an absolute 4-dimensional spacetime. With this approach time was simply merged in with the three spatial dimensions (x, y, z) into a 4-dimensional spacetime of (x, y, z, t), and time just became a strange cousin of the other spatial dimensions. The distance between events in 4-dimensional spacetime is called the interval s and is defined just like the distance d between points in 3-dimensional space.

Distance between points in space:
d² = ∆x² + ∆y² + ∆z²

Interval between events in spacetime:
s² = ∆x² + ∆y² + ∆z² + i²∆t²

where i² = -1

In 4-dimensional spacetime, the only distinguishing thing about time is that you have to multiply time by the imaginary number i in the equation for the interval between events. Otherwise, time is simply treated like the other spatial dimensions of x, y and z. Essentially, with the 4-dimensional spacetime Block Universe model of the Universe, the Universe became a static tube of salami that had seemingly always existed. Observers moving relative to each other simply sliced the static tube of salami at different angles. For example, in Figure 9 we see the Block Universe tube of salami cut at two different angles. In the first cut of the salami two events happen at different positions in space and also different positions in time so the events are not simultaneous. This is the situation for our second Einstein on the ground who observed two photons being emitted at different places in space and also at different times. The second salami is cut at a different angle, which again has the two photons being emitted at different positions in space, but this time both photons are emitted at the same time on the time slice of salami. This is the situation for our first Einstein riding on the platform who observed two photons being emitted at different places in space, but at the same time in his reference frame.

Figure 9 – The special theory of relativity extended the Block Universe model by introducing the concept of an absolute spacetime.

This new 4-dimensional spacetime Block Universe model, brought on by the special theory of relativity in 1905, really seemed to kill the concept of an absolute space and an absolute time because space and time got thoroughly blended together in the process of making the spacetime salami so that you could no longer tell them apart. If I am moving relative to you that means that my time can become your space and vice versa. But what about Newton’s bucket? The water in Newton’s bucket was surely telling us that it was rotating with respect to something. But don’t forget that the water in Newton’s bucket was rotating, and was thus accelerating, because the direction of the water’s velocity in the rotating bucket was constantly changing so that the water could move in a circle, and that is acceleration. The special theory of relativity does not work for accelerating reference frames like a spinning bucket of water. For that we need Einstein’s general theory of relativity (1915). With the general theory of relativity Einstein extended the 4-dimensional spacetime Block Universe model to all forms of motion, including accelerating reference frames, and in the process demonstrated that accelerated motion was essentially the same thing as gravity. In the general theory of relativity gravity is no longer a force between masses. Instead, gravity becomes another “fake force” like the centrifugal force. When you make a sharp turn in your car at high speed your body feels the “fake force” of centrifugal force pulling you away from the center of curvature of your turn. But that “fake force” is really just your body trying to move in a straight line through space according to Newton’s first law of motion. Similarly, in the general theory of relativity the gravitational force your body feels pulling you down to the Earth is simply your body trying to move in a straight line through spacetime and is also a “fake force”! If you jump off a cliff and find yourself in free fall, moving in a straight line through spacetime, gravity suddenly disappears, just as if you had been thrown from a car making a tight turn and had found yourself moving in a straight line through space with the “fake” centrifugal force suddenly disappearing too. In order to make that adjustment to the special theory of relativity that used flat time slices through the 4-dimensional spacetime salami, Einstein had to make the 4-dimensional spacetime salami internally curvy. In the general theory of relativity matter, energy and pressure can all cause spacetime to warp and become curvy, and it is the curvy 4-dimensional spacetime that creates the illusion of gravity. When there are no significant amounts of matter, energy or pressure present, the 4-dimensional spacetime salami is not internally distorted, so that slices through it are flat and we return again to the special case of flat spacetime that is covered by the special theory of relativity. Thus, when the surface of the water in a spinning bucket forms a concave shape, it is not moving relative to absolute space, it is moving relative to absolute spacetime.

Figure 10 – In the general theory of relativity the 4-dimensional spacetime salami becomes internally curvy.

Cosmological Problems
Currently physicists and cosmologists are trying to explain the apparent fine-tuning of our Universe that allows for intelligent beings such as ourselves to exist. It seems that the current working hypothesis is that eternal chaotic inflation produces an infinite multiverse composed of an infinite number of separate causally isolated universes, such as our own, where inflation has halted, and each of these causally-separated universes may also be infinite in size too. As inflation halts in these separate universes, the Inflaton field that is causing the eternal chaotic inflation of the entire multiverse continues to inflate the space between each causally-separated universe at a rate that is much greater than the speed of light, quickly separating the universes by vast distances that can never be breached. Thus most of the multiverse is composed of rapidly expanding spacetime driven by inflation, sparsely dotted by causally-separated universes where the Inflaton field has decayed into matter and energy and inflation has stopped. Each of the causally-separated universes, where inflation has halted, will then experience a Big Bang of its own as the Inflaton field decays into matter and energy, leaving behind a certain level of vacuum energy. The amount of vacuum energy left behind will then determine the kind of physics each causally-separated universe experiences. In most of these universes the vacuum energy level will be too positive or too negative to create the kind of physics that is suitable for intelligent beings, creating the selection process that is encapsulated by the weak Anthropic Principle. This goes hand-in-hand with the current thinking in string theory that you can build nearly an infinite number of different kinds of universes, depending upon the geometries of the 11 dimensions hosting the vibrating strings and branes of M-Theory, the latest rendition of string theory. Thus an infinite multiverse has the opportunity to explore all of the nearly infinite number of possible universes that string theory allows, creating Leonard Susskind’s Cosmic Landscape (2006). In this model, our Universe becomes a very rare and improbable Universe.

Lee Smolin has problems with the above model for a variety of reasons. Lee Smolin is a realist in that he has a high level of confidence that there is a true physical reality that exists even if we are not around to observe it. Lee Smolin is also not a positivist or instrumentalist at heart, simply looking for effective theories that make good predictions of how physical systems behave, he is instead looking for explanations of physical reality, and that means he expects more out of a cosmological theory than most. He is also a strong follower of Karl Popper - a good cosmological theory must be falsifiable. If a cosmological theory cannot be proven wrong by observation then it is not of much use for Lee Smolin. This presents a problem for the current working hypothesis outlined above. In that model nearly all of the multiverse is beyond our cosmic horizon of about 46 billion light years, and consequently, is unobservable. Yet most people would contend that if we were suddenly transported 100 billion light years from our current position in our Universe we would most likely see exactly what we see from our current position. We would see hundreds of billions of galaxies all receding from us as the Universe expanded. But at a distance of 100 billion light years we would be causally disconnected from our current position and consequently unobservable. The fact that most of our own Universe is indeed unobservable has caused many physicists and cosmologists who have a high level of confidence in the eternal chaotic inflation model to forsake Karl Popper and instead adopt what Andrei Linde calls the Sherlock Holmes approach to science:

“when you have eliminated the impossible, whatever remains, however improbable, must be the truth.”

Of course how do you know when you have truly eliminated all of the impossibles? Perhaps someday you will also find that your current working hypothesis is also impossible. Or perhaps you will find that there are a very large number of possible theories that are not impossible. How do you then choose? This seems to be the most difficult problem in physics and cosmology today. Either things are too far away to be seen because they are more distant than our current cosmic horizon of 46 billion light years, or as with string theory, they are too small for us to observe even with the LHC particle collider by many orders of magnitude. And probably we will never be able to build a particle collider with enough energy to probe the structures at the heart of string theory.

Lee Smolin's Solution
Lee Smolin contends that we need a new cosmological theory that goes beyond the model outlined above that explains why our Universe has the physical laws that it does and why it started out with the initial conditions that it did. In Time Reborn Lee Smolin proposes that the solution to this fine-tuning problem of the Universe is for physicists and cosmologists to forsake the Block Model of the Universe and to reinstate Newton's concept of an absolute time. In doing so, he becomes a Presentist, meaning that he considers time to be real and the most fundamental characteristic of the Universe. For Presentists, only the present moment exists, and the physical laws of the Universe can change with time.

Figure 11 - For a Presentist time is real and only the present moment exists.

Reinstating Newton's concept of an absolute time runs counter to the Block Universe model outlined above to an extreme, but Lee Smolin presents a number of compelling arguments to explain why it is necessary to do so. His major concern is that the current cosmological model can never be validated by experimental or observational data because it is not falsifiable. In The Trouble with Physics, he outlined numerous cases in the past when some theoretical physicists were found to be running on pure mathematics, without the benefit of any validation by empirical evidence, only later to find that their mathematical theories collapsed when empirical data finally arrived on the scene.

Lee Smolin also points out that another problem with the current cosmological model is that all of the current theories of physics are effective theories and that the model extends these fundamentally flawed effective theories to the entire cosmos as a whole. Recall that an effective theory is an approximation of reality that only holds true over a certain restricted range of conditions and only provides for a certain depth of understanding of the problem at hand. For example, Newtonian mechanics is an effective theory that makes very good predictions for the behavior of objects moving less than 10% of the speed of light and which are bigger than a very small grain of dust. These limits define the effective range over which Newtonian mechanics can be applied to solve problems. For very small things we must use quantum mechanics and for very fast things moving in strong gravitational fields, we must use relativity theory. All of the current theories of physics, such as Newtonian mechanics, Newtonian gravity, classical electrodynamics, thermodynamics, statistical mechanics, the special and general theories of relativity, quantum mechanics, and the quantum field theories of QED and QCD are just effective theories that are based upon models of reality, and all these models are approximations - all these models are fundamentally "wrong", but at the same time, these effective theories make exceedingly good predictions of the behavior of physical systems over the limited ranges in which they apply. But all of these effective theories were only validated by doing the "physics in a box" outlined above in which we attempted to isolate a subsystem of the Universe from the rest of the Universe before running an experiment on the subsystem. And in all cases we used external clocks to run the experiments that were not part of the subsystem being investigated. Clearly, that approach cannot be applied to the entire Universe.

However, reinstating the concept of an absolute time does present a major problem for relativity theory because space and time get mixed together into a 4-dimensional spacetime in relativity, and observers in relative motion with each other will disagree about the exact times and distances between observed events. The way around this problem is to define absolute time as a preferred time, and in relativity theory the preferred time is called the "proper time" and is the time measured by a clock carried along by an observer. So to extend the concept of proper time to an absolute time we need to also define an absolute spatial reference frame too. Lee Smolin suggests that this absolute reference frame can best be provided by the familiar CMBR - Cosmic Microwave Background Radiation. Normally the CMBR is depicted as shown in Figure 12 which is corrected for the motion of our galaxy relative to the CMBR in order to reveal the subtle bumps caused by the original clumping of dark matter in the early universe that led to galactic clusters. In truth, our galaxy is traveling about 627 km/sec relative to the CMBR photons that are arriving to us from all directions. This causes the CMBR photons arriving to us from the direction in which our galaxy is moving to become blue-shifted to a higher frequency than for CMBR photons that arrive perpendicular to our direction of motion. Similarly, on the other side of the sky, 1800 in the opposite direction, we observe red-shifted CMBR photons trying to catch up with us as our galaxy moves at 627 km/sec through the sea of CMBR photons. If we consider the CMBR photons to be at absolute rest, we now have an absolute spatial reference frame, and a clock at rest with respect to this sea of CMBR photons will measure a proper time that can be thought of as an absolute time. This sort of brings us back full circle to Newton's original model of an absolute space and time, so is a bit heretical in nature. However, many physicists and cosmologists have already made this transition for cosmological purposes. For example, physicists and cosmologists often refer to the "peculiar" motion of galaxies relative to the "Hubble flow". Because our Universe is expanding, galaxies that are many billions of light years away from us are apparently traveling at a good portion of the speed of light away from us. But most of this apparent motion is not "through" spacetime, it is "with" spacetime as the Universe expands. For the most part these distant galaxies are merely floating along in the Hubble flow as the Universe expands, like a raft floating along in a river as it is carried downstream by the current of the river. Granted, these distant galaxies will also have some "peculiar" velocities relative to us, as they orbit the center of mass of their galactic clusters, but for the most part they are merely floating along in the Hubble flow as the Universe expands. Because these distant galaxies are just floating along in the Hubble flow, and are not moving through spacetime relative to us, their clocks will tick along at about the same rate as our clocks do. So essentially, all of the galaxies in the observable Universe are all just floating along in the Hubble flow for the most part and experiencing the absolute time defined by the proper time of clocks that are not moving at all relative to the Hubble flow and the CMBR.

Figure 12 - Normally, people show the CMBR data corrected for the motion of our galaxy in order to reveal the subtle bumps caused by the original clumping of dark matter in the early universe that led to galactic clusters.

Figure 13 - However, the raw uncorrected CMBR data shows that our galaxy is moving at about 627 km/sec relative to the CMBR photons. We are moving towards the blue section in the sky and away from the red section. Because we are moving away from one point in the sky and towards another point in the sky, these directions are 1800 apart in the sky .

The Emergence of Space
Lee Smolin's desire for a new cosmic model does not bring us entirely back to Newton's absolute space and time because it really only posits an absolute time that is fundamental to the Universe. Space is an entirely different matter. A major problem with most of the current effective theories of physics is that they are background-dependent theories, meaning that the laws these theories encompass operate upon a stage or background. For Newtonian mechanics the stage or background is an absolute space that exists even if nothing else in the Universe is present. For special relativity theory the stage is a 4-dimensional spacetime. For the Standard Model of particle physics the stage is the flat spacetime of the special theory of relativity. And for string theory the stage is an 11-dimensional spacetime in which the strings and branes vibrate. Currently, the only background-independent effective theory we have is the general theory of relativity. In the general theory of relativity, 4-dimensional spacetime is dynamic and changing, and is not static. Consequently, it makes sense that an approach to unifying quantum mechanics with gravity should also be background-independent. And there are background-independent theories such as loop quantum gravity. In loop quantum gravity space is quantized into a network of nodes called a spin network. The minimum distance between nodes is about one Planck length of about 10-35 meters. Loop quantum gravity is a background-independent theory because the spin network can be an emergent property of the Universe that evolves with time. Note that these background-independent theories are very much like the network of nodes that constitute the Software Universe. The distance between objects in the Software Universe is defined by the number of hops between nodes on a network and the same goes for background-independent theories like loop quantum gravity.

Figure 14 - In loop quantum gravity space is quantized into a collection of nodes that are very much like the nodes that constitute the Software Universe. In both cases the distance between things is the number of hops between nodes.

The Evolution of the Multiverse
With a new cosmic background-independent theory that allows for the emergence of space it is possible to formulate another explanation for the apparent fine-tuning of the Universe and explain why our Universe behaves as it does and why it began with the initial conditions that it did. In The Life of the Cosmos (1997) Lee Smolin proposed that since the only other example of similar fine-tuning in our Universe is manifested in the biosphere, we should look to the biosphere as an explanation for the fine-tuning that we see in the cosmos. Living things are incredible examples of highly improbable fine-tuned systems, and this fine-tuning was accomplished via the Darwinian mechanisms of innovation honed by natural selection. Along these lines, Lee Smolin proposed that when black holes collapse they produce a white hole in another universe, and the white hole is observed in the new universe as a Big Bang. He also proposed that the physics in the new universe would essentially be the same as the physics in the parent universe, but with the possibility for slight variations. Therefore a universe that had physics that was good at creating black holes would tend to outproduce universes that did not. Thus a selection pressure would arise that selected for universes that had physics that was good at making black holes, and a kind of Darwinian natural selection would occur in the Cosmic Landscape of the Multiverse. Thus over an infinite amount of time, the universes that were good at making black holes would come to dominate the Cosmic Landscape. He called this effect cosmological natural selection. One of the major differences between Lee Smolin's view of the Multiverse and the model outlined above that is based upon eternal chaotic inflation is that in Lee Smolin's Multiverse we should most likely find ourselves in a universe that is very much like our own and that has an abundance of black holes. Such universes should be the norm, and not the exception. In contrast, in the eternal chaotic inflation model we should only find ourselves in a very rare universe that is capable of supporting intelligent beings.

For Smolin, the intelligent beings in our Universe are just a fortuitous by-product of making black holes because, in order for a universe to make black holes, it must exist for many billions of years, and do other useful things, like easily make carbon in the cores of stars, and all of these factors aid in the formation of intelligent beings, even if those intelligent beings might be quite rare in such a universe. I have always liked Lee Smolin’s theory about black holes in one universe spawning new universes in the Multiverse, but I have always been bothered by the idea that intelligent beings are just a by-product of black hole creation. We still have to deal with the built-in selection biases of the weak Anthropic Principle. Nobody can deny that intelligent beings will only find themselves in a universe that is capable of supporting intelligent beings. I suppose the weak Anthropic Principle could be restated to say that black holes will only find themselves existing in a universe capable of creating black holes, and that a universe capable of creating black holes will also be capable of creating complex intelligent beings out of the leftovers of black hole creation.

Towards the end of In search of the multiverse : parallel worlds, hidden dimensions, and the ultimate quest for the frontiers of reality (2009), John Gribbin proposes a different solution to this quandary. Perhaps intelligent beings in a preceding universe might be responsible for creating the next generation of universes in the Multiverse by attaining the ability to create black holes on a massive scale. For example, people at CERN are currently trying to create mini-black holes with the LHC collider. Currently, it is thought that there is a supermassive black hole at the center of the Milky Way Galaxy and apparently all other galaxies as well. In addition to the supermassive black holes found at the centers of galaxies, there are also numerous stellar-mass black holes that form when the most massive stars in the galaxies end their lives in supernova explosions. For example, our Milky Way galaxy contains several hundred billion stars, and about one out of every thousand of those stars is massive enough to become a black hole. Therefore, our galaxy should contain about 100 million stellar-mass black holes. Actually, the estimates run from about 10 million to a billion black holes in our galaxy, with 100 million black holes being the best order of magnitude guess. So let us presume that it took the current age of the Milky Way galaxy, about 10 billion years, to produce 100 million black holes naturally. Currently, the LHC collider at CERN can produce at least 100 million collisions per second, which is about the number of black holes that the Milky Way galaxy produced in 10 billion years. Now imagine that we could build a collider that produced 100 million black holes per second. Such a prodigious rate of black hole generation would far surpass the natural rate of black hole production of our galaxy by a factor of about 1020. Clearly, if only a single technological civilization with such technological capabilities should arise anytime during the entire history of each galaxy within a given universe, such a universe would spawn a huge number of offspring universes, compared to those universes that could not sustain intelligent beings with such capabilities. As Lee Smolin pointed out, we would then see natural selection in action again because the Multiverse would come to be dominated by universes in which it was easy for intelligent beings to make black holes with a minimum of technology. The requirements simply would be that it was very easy to produce black holes by a technological civilization, and that the universe in which these very rare technological civilizations find themselves is at least barely capable of supporting intelligent beings. It seems that these requirements describe the state of our Universe quite nicely. This hypothesis helps to explain why our Universe seems to be such a botched job from the perspective of providing a friendly home for intelligent beings and software. All that is required for a universe to dominate the Cosmic Landscape of the Multiverse is for it to meet the bare minimum of requirements for intelligent beings to evolve, and more importantly, allow those intelligent beings to easily create black holes within them. Since software is needed in all such universes to run the machines that generate the black holes, that explains why our Universe is capable of supporting software, but just barely so, and that is why software is so rare within our galaxy and Universe.

In What’s It All About?, I described my current working hypothesis for what’s it all about. I explained that my current working hypothesis was that our Multiverse was a form of self-replicating mathematical information that I dubbed the FEU – the Fundamental Essence of the Universe. In that posting I alluded to Eugene Wigner’s oft-cited paper The Unreasonable Effectiveness of Mathematics in the Natural Sciences (1960), which is available at:

and to the strange fact that our Universe seems to behave mathematically to an extreme. In this model, like in Max Tegmark's Mathematical Universe Hypothesis, our Universe behaves very mathematically because it is a form of self-replicating mathematical information that might replicate by spawning black holes. And in my current model the Software Universe is also a form of self-replicating mathematical information based upon binary arithmetic and binary logical operations that exists in a background-independent sense on a vast network of computing nodes similar to what is found in loop quantum gravity.

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Steve Johnston