Consciousness As Mental, As Physical

It’s been argued that a scientist who grew up in a black and white room and never saw the color red could learn everything there is to know about the physics of light and the physiology of the human body, including what happens in the brain when someone sees red, but not know what red looks like. Presumably, a blind scientist with the same training would be in the very same position. Likewise, a deaf scientist could know everything about the physics and physiology involved in hearing a violin but not really know what a violin sounds like. This is supposed to show that there is something in the universe beyond the reach of the physical sciences: the mysterious mental phenomenon of consciousness.

“Mental” is a word I haven’t used much (or at all) in writing about consciousness, yet consciousness is clearly a mental phenomenon if anything is. But what does it mean for a phenomenon to be “mental”?

The obvious answer, although it’s not very helpful, is that “mental” means “not physical”. But what does that mean?

An exchange of letters I referred to last month between the philosopher Thomas Nagel and a professor of bioengineering, Roy Black, tries to deal with the question. Prof. Black criticizes the idea that “nonphysical factors” are involved in consciousness:

As is frequently noted, the physical basis of life itself used to be just as mysterious as consciousness, and it’s now well explained by biochemistry and molecular biology, without nonphysical factors. So although science as we know it doesn’t explain the link between neurons and consciousness, why expect the link to be “nonphysical” rather than “novel physical”? What is a nonphysical factor, anyway? If the dark energy propelling the expansion of the universe, the strong force holding atomic nuclei together, etc., etc., are physical, do we really need anything more exotic?

… Lots of things in biology—like the development of an organism from an egg—seem impossible, until we stretch our imagination to conceive of simple precursors and mechanisms that could have been worked on by natural selection over billions of years. To quote one of [the philosopher Daniel Dennett’s] nice lines, “evolution is a process that depends on amplifying things that almost never happen.” We need to determine what “thing,” what activity of neurons beyond activating other neurons, was amplified to the point that consciousness arose. What would a precursor of “feeling like” be? That’s what we need to stretch our imaginations further to figure out.

Prof. Nagel responds, but his response is based on an assumption:

The difficulty is that conscious experience has an essentially subjective character—what it is like for its subject, from the inside—that purely physical processes do not share [how does he know this?]. Physical concepts describe the world as it is in itself, and not for any conscious subject….

I agree with Black that “we need to determine what ‘thing’, what activity of neurons beyond activating other neurons, was amplified to the point that consciousness arose.” But I believe this will require that we attribute to neurons, and perhaps to still more basic physical things and processes, some properties that in the right combination are capable of constituting subjects of experience like ourselves, to whom sunsets and chocolate and violins look and taste and sound as they do. These, if they are ever discovered, will not be physical properties, because physical properties, however sophisticated and complex, characterize only the order of the world extended in space and time, not how things appear from any particular point of view [again, how does he know this?].

Nagel’s assumption is that a purely physical process cannot have a subjective character (it cannot “feel like something”). It cannot be “how things appear” from a particular point of view. But if consciousness is a physical process, it does have a subjective character. In that case, how things feel or appear are indeed physical properties of a process that occurs in space and time (it happens inside your head when you’re conscious).

Here’s my take on the mental/physical distinction. Nobody knows what the universe contains at the most fundamental level (or if there is a most fundamental level). But suppose that quantum field theory is correct and, quoting Prof. David Tong of Cambridge University (who I wrote about earlier this year):

The best theories we have tell us that the fundamental building blocks of nature are not particles but something much more nebulous and abstract. The fundamental building blocks of nature are fluid-like substances which are spread throughout the entire universe and ripple in strange and interesting ways. That’s the fundamental reality in which we live. These fluid-like substances, we have a name for, we call them “fields”.

Furthermore, when the fields ripple or are agitated in certain ways, we get sub-atomic particles. An electron, for example, is a kind of ripple in the electron field.

So when I say that consciousness is a physical process, what I’m saying is that consciousness is at bottom constructed from one or more quantum-level fields – or whatever the fundamental building blocks of the universe are – that somehow interact with the quantum-level fields – or other building blocks – from which everything else in the universe is constructed. Maybe consciousness involves a kind of fundamental field that physicists can’t measure or detect yet. Maybe it involves a new kind of interaction between fundamental fields that physicists already know about.

But consciousness seems to be part of the natural world in the same way other physical phenomena are. And because it’s part of the natural world – not a kind of free-floating spiritual or supernatural substance or phenomenon – consciousness can represent other physical events and processes outside itself. Consciousness being part of the world is why we can be consciously aware of our bodies and the world around us.

“Mental”, therefore, refers to what happens in our minds, but at bottom mental phenomena are physical phenomena. Consciousness, like gravity, digestion and baseball, is one of the things that happens in the world. In other words, the “mental” is a subset of the “physical”. Or so it seems to me.

The Real Building Blocks of the Universe (So Far)

Thales of Miletus is generally credited with being “the first philosopher in the Greek tradition [and] as the first individual in Western civilization known to have entertained and engaged in scientific philosophy” (Wikipedia). Less formally, he’s known as the ancient Greek who thought everything is made of water.

But that wasn’t a crazy idea at the time:

Thales [c. 624 – c. 546 BC] is recognized for breaking from the use of mythology to explain the world and the universe, and instead explaining natural objects and phenomena by theories and hypothesis, i.e. science. Almost all the other Pre-Socratic philosophers followed him in explaining nature as deriving from a unity of everything based on the existence of a single ultimate substance, instead of using mythological explanations. Aristotle reported Thales’ hypothesis that the originating principle of nature and the nature of matter was a single material: water (Wikipedia).

Jumping forward around 2,500 years, we’re still trying to figure out what everything is made of. If you’d asked me a few days ago, and given me a few seconds to think about it, I’d probably have said everything is made of very tiny particles like quarks and photons:


Fortunately, however, the scales have been lifted from my eyes. All it took was watching a lecture by a physicist named David Tong. It’s called “Quantum Fields: The Real Building Blocks of the Universe”. Here’s how he explains the situation on his University of Cambridge webpage:


We learn in school that the basic building blocks of matter are particles. In fact, we often continue to teach this in universities where we explain that quarks and electrons form the lego-bricks from which all matter is made.

But this statement hides a deeper truth. According to our best laws of physics, the fundamental building blocks of Nature are not discrete particles at all. Instead they are continuous fluid-like substances, spread throughout all of space. We call these objects fields.

The most familiar examples of fields are the electric and magnetic field. The ripples in these fields give rise to what we call light or, more generally, electromagnetic waves. The field [relating to a magnet is shown here].


From Fields to Particles

If you look closely enough at electromagnetic waves, you’ll find that they are made out of particles called photons. The ripples of the electric and magnetic fields get turned into particles when we include the effects of quantum mechanics.

But this same process is at play for all other particles that we know of. There exists, spread thinly throughout space, something called an electron field. Ripples of the electron field get tied up into a bundle of energy by quantum mechanics. And this bundle of energy is what we call an electron. Similarly, there is a quark field, and a gluon field, and Higgs boson field. Every particle your body — indeed, every particle in the Universe — is a tiny ripple of the underlying field, moulded into a particle by the machinery of quantum mechanics.


These fields fill the universe, even what seems to be empty space. All of the particles the physicists have identified are manifestations of these fields. In some sense, apparently, so are we. 

Prof. Tong gave his lecture at the Royal Institution in London in November. It’s an hour-long introduction to Quantum Field Theory for the general public. He’s an entertaining speaker and, as an added bonus, he looks and sounds a lot like the comedian John Oliver.

If you want to jump ahead a little, it’s about nine minutes in when he announces that:

The best theories we have tell us that the fundamental building blocks of nature are not particles but something much more nebulous and abstract. The fundamental building blocks of nature are fluid-like substances which are spread throughout the entire universe and ripple in strange and interesting ways. That’s the fundamental reality in which we live. These fluid-like substances, we have a name for, we call them “fields”.

Have fun. After this, you may never see the world in the same way.


(Hmm, notice how I didn’t mention You Know Who once? This should not suggest that anything is back to normal yet. Far from it.)

There’s Something Called “Quantum Biology”

Occasionally you hear some news and wonder “Why didn’t I ever hear about this before?” That was my reaction to the news that scientists have been investigating something called “quantum biology” for the past 20 years or so.

Last week, there was a link on the always interesting Self Aware Patterns blog to a Guardian article called “You’re Powered by Quantum Mechanics. No, Really…”. The article was written by two scientists, the physicist Jim Al-Khalili and the geneticist Johnjoe McFadden. Here’s the news I found extremely surprising:

As 21st-century biology probes the dynamics of ever-smaller systems – even individual atoms and molecules inside living cells – the signs of quantum mechanical behaviour in the building blocks of life are becoming increasingly apparent. Recent research indicates that some of life’s most fundamental processes do indeed depend on weirdness welling up from the quantum undercurrent of reality.

Really? People with various qualifications have speculated for years about quantum mechanical phenomena occurring in the human brain, usually in an attempt to justify belief in free will. But this is real science based on experimental results (albeit with a dose of speculation too).

The McFadden/Al-Khalili article cites three examples in which quantum phenomena appear to play a crucial role in biology. First, enzymes appear to work via quantum tunneling:

Enzymes … speed up chemical reactions so that processes that would otherwise take thousands of years proceed in seconds inside living cells. Life would be impossible without them. But how they accelerate chemical reactions by such enormous factors, often more than a trillion-fold, has been an enigma. Experiments over the past few decades, however, have shown that enzymes make use of a remarkable trick called quantum tunnelling to accelerate biochemical reactions. Essentially, the enzyme encourages electrons and protons to vanish from one position in a biomolecule and instantly rematerialise in another, without passing through the gap in between – a kind of quantum teleportation. 

Second, photosynthesis seems to involve wave/particle duality:

The first step in photosynthesis is the capture of a tiny packet of energy from sunlight that then has to hop through a forest of chlorophyll molecules …. The problem is understanding how the packet of energy appears to so unerringly find the quickest route through the forest. An ingenious experiment … revealed that the energy packet was not hopping haphazardly about, but performing a neat quantum trick. Instead of behaving like a localised particle travelling along a single route, it behaves quantum mechanically, like a spread-out wave, and samples all possible routes at once to find the quickest way.

Third, there are animals who appear to rely on quantum entanglement:

A third example of quantum trickery in biology … is the mechanism by which birds and other animals make use of the Earth’s magnetic field for navigation. Studies of the European robin suggest that it has an internal chemical compass that utilises an astonishing quantum concept called entanglement, which Einstein dismissed as “spooky action at a distance”. This phenomenon describes how two separated particles can remain instantaneously connected via a weird quantum link. The current best guess is that this takes place inside a protein in the bird’s eye, where quantum entanglement makes a pair of electrons highly sensitive to the angle of orientation of the Earth’s magnetic field, allowing the bird to “see” which way it needs to fly.

McFadden has published another article at Aeon in which he further discusses the examples above and throws in a possible relationship between quantum mechanics and the sense of smell. In addition, a quick search online turned up an article from the MIT Technology Review explaining how quantum entanglement may stop large DNA molecules from falling apart and an overview of developments in quantum biology from the BBC.

Not everyone is convinced of the quantum nature of these phenomena, of course, and research continues. Still, I think this is all extremely interesting. In one sense, it’s surprising that living things could employ phenomena like entanglement and quantum tunneling that seem so bizarre and so removed from ordinary life. But in another sense, it shouldn’t be a surprise if millions of years of evolution have allowed both plants and animals to take advantage of such powerful and fundamental natural phenomena.

Time Flies and Stuff Happens

Jim Holt has written a nice article on that eternally perplexing subject: the nature of time. As expected, it left me properly perplexed.

Consider this passage:

Events judged to be in the past by one observer may still lie in the future of another; therefore, past and present must be equally definite, equally “real.” In place of the fleeting present, we are left with a vast frozen timescape—a four-dimensional “block universe”… Nothing is “flowing” from one event to another. As the mathematician Hermann Weyl memorably put it, “The objective world simply is; it does not happen. Einstein, through his theory of relativity, furnished a scientific justification for a philosophical view of time [called] “eternalism.” Time, according to this view, belongs to the realm of appearance, not reality. The only objective way to see the universe is as God sees it: sub specie aeternitatis [“under the aspect of eternity”].

But wait (if it’s appropriate to use that term). What is the ultimate fate of the universe?

Ever since its birth in the Big Bang, some 13.82 billion years ago, the universe has been expanding. If this expansion continues forever … the stars will burn out; black holes will evaporate; atoms and their subatomic constituents will decay. In the deep future, the remaining particles … will spread out into the void, becoming so distant from one another that they will cease to interact. Space will become empty except for the merest hint of “vacuum energy”. Yet in this future wasteland of near nothingness, time will go on; random events will continue to occur; things will “fluctuate” into existence, thanks to the magic of quantum uncertainty, only to disappear again into the void….But there is another possible cosmic fate. By and by, at some point in the far future, the expansion that the universe is currently undergoing might be arrested—maybe by gravity, maybe by some force that is currently unknown. Then all the hundreds of billions of galaxies will begin to collapse back on themselves, eventually coming together in a fiery all-annihilating implosion.

Well, you might ask, which is it? Does time belong to the realm of appearance, not reality? Or has the universe been expanding for 13.82 billion years?

Is it correct to say the “objective world simply is; it does not happen”? Or should we say that stuff happens all the time?

Holt is probably correct when he says that “most physicists … agree with Einstein that time’s passage is an illusion; they are eternalists.” Here’s how the “Time” article in the Stanford Encyclopedia of Philosophy defines eternalism:

Eternalism says that objects from both the past and the future exist just as much as present objects. According to eternalism, non-present objects like Socrates and future Martian outposts exist…, even though they are not currently present. We may not be able to see them at the moment, on this view, and they may not be in the same space-time vicinity that we find ourselves in …, but they should nevertheless be on the list of all existing things.

The idea here is that the history of the universe may be thought of as a series of events on a continuum that stretches from the past to the future, but which never includes a moment that is “now”. We can say that one event is earlier or later than another (e.g. the Big Bang is about 14 billion years earlier than December 1, 2014), but it’s wrong to think that the moment you or I perceive as “now” has any special significance, so far as the universe is concerned.

It’s as if the timeline of the universe were a long, straight line between points A and B. Between A and B there are many other points, but none of them is more real than any other. Instead, each point on the line and each moment in the history of the universe (and every object that has ever existed or ever will) exists in the very same way.

Nevertheless, as Holt goes on to say, some physicists are “presentists”. So are some philosophers (as well as most “normal” people who have ever thought about the issue). Presentists believe that “now is a special moment that really advances…; this would still be true, they believe, even if there were no observers like us in the universe”. In the words of the Stanford Encyclopedia:

Presentism is the view that only present objects exist. … According to Presentism, if we were to make an accurate list of all the things that exist … there would be not a single non-present object on the list. Thus, you and the Taj Mahal would be on the list, but neither Socrates nor any future Martian outposts would be included.  

I confess that I find presentism much easier to understand than eternalism. In fact, eternalism sounds sufficiently crazy that there must be extremely good reasons for very smart people to believe it.

Is every object and every event in the history of the universe equally real, so that the biggest triceratops who ever lived and the dinner you’re going to have next New Year’s Eve are just as real as the chair you’re sitting on? Holt says Einstein answered that question and the answer is “Yes!”:

What Einstein [showed] was that there is no universal “now.” Whether two events are simultaneous is relative to the observer. And once simultaneity goes by the board, the very division of moments into “past,” “present,” and “future” becomes meaningless. Events judged to be in the past by one observer may still lie in the future of another; therefore, past and present must be equally definite, equally “real.” In place of the fleeting present, we are left with a vast frozen timescape—a four-dimensional “block universe.”

Maybe that’s the conclusion to be drawn from the scientific evidence. On the other hand, quoting the Stanford Encyclopedia again:

Perhaps it can be plausibly argued that while relativity entails that it is physically impossible to observe whether two events are absolutely simultaneous, the theory nevertheless has no bearing on whether there is such a phenomenon as absolute simultaneity.

Thinking about what might be the case beyond our powers of observation may qualify as metaphysics rather than physics, but it seems to me that change is a fundamental feature of the universe, time is the rate of change, and wherever and whenever changes occur, time is passing. My “now” is different from your “now” in the same way that my “here” is different from your “here”. But each “now” marks a real point in time (a point in the overall history of the universe), just like each “here” marks a real point in space (the universe’s overall expanse).

Eternalism, however, treats time as if it’s one more spatial dimension, a dimensioin in which all locations are equally real. I don’t think time is like that at all. Some moments (or temporal locations) were real, some will be real, and when a moment becomes real, it’s now. Not merely from our perspective, but in reality.

Anyway, that’s my opinion. If you and I aren’t more real than Socrates or the 75th President of the United States (whoever she turns out to be) in a very significant sense, meaning that we exist and they sure don’t, well, this isn’t a universe I want to spend time in.

That God Playing Dice With the Universe Thing Again

Quanta has an article with the intriguing title: “Have We Been Interpreting Quantum Mechanics Wrong This Whole Time?”. Far be it from me to interpret quantum mechanics at all, so I’ll merely quote:

…That nature is inherently probabilistic — that particles have no hard properties, only likelihoods, until they are observed — is directly implied by the standard equations of quantum mechanics. But now a set of surprising experiments with fluids has revived old skepticism about that worldview. The bizarre results are fueling interest in an almost forgotten version of quantum mechanics, one that never gave up the idea of a single, concrete reality.

The experiments involve an oil droplet that bounces along the surface of a liquid. The droplet gently sloshes the liquid with every bounce. At the same time, ripples from past bounces affect its course. The droplet’s interaction with its own ripples, which form what’s known as a pilot wave, causes it to exhibit behaviors previously thought to be peculiar to elementary particles — including behaviors seen as evidence that these particles are spread through space like waves, without any specific location, until they are measured.

Particles at the quantum scale seem to do things that human-scale objects do not do. They can tunnel through barriers, spontaneously arise or annihilate, and occupy discrete energy levels. This new body of research reveals that oil droplets, when guided by pilot waves, also exhibit these quantum-like features.

Assuming that continued experimentation confirms that the probabilistic behavior of these droplets and fluids mirrors the behavior of quantum-level particles, the question would be: Is this similarity a mere coincidence or does it indicate that there is an underlying deterministic basis for apparently spooky, indeterministic quantum events? 

To some researchers, the experiments suggest that quantum objects are as definite as droplets, and that they too are guided by pilot waves — in this case, fluid-like undulations in space and time. These arguments have injected new life into a deterministic (as opposed to probabilistic) theory of the microscopic world first proposed, and rejected, at the birth of quantum mechanics.

“This is a classical system that exhibits behavior that people previously thought was exclusive to the quantum realm, and we can say why,” said John Bush, a professor of applied mathematics at the Massachusetts Institute of Technology who has led several recent bouncing-droplet experiments. “The more things we understand and can provide a physical rationale for, the more difficult it will be to defend the ‘quantum mechanics is magic’ perspective.”

The great French physicist Louis De Broglie first proposed a deterministic pilot-wave theory in the 1920s. David Bohm famously proposed a later version. According to the article, John Stewart Bell, the author of Bell’s Theorem, which supposedly shows that quantum mechanics cannot be deterministically explained by “hidden variables”, was also a proponent:

In 1986, [Bell] wrote that pilot-wave theory “seems to me so natural and simple, to resolve the wave-particle dilemma in such a clear and ordinary way, that it is a great mystery to me that it was so generally ignored.” 

Of course, many physicists are skeptical, as they should be. Overturning the standard interpretation of quantum mechanics (the indeterministic “Copenhagen” interpretation) would be a very big deal. But doing so would make our universe much less mysterious (no more God playing dice). And it would allow physicists to give up the increasingly popular idea that there are many, many universes (the “multiverse” interpretation of QM). We might then go back to thinking of the universe as a unique, cozy place where everything happens for a reason.

Clearing Up This Multiple Universe Thing (Maybe)

I haven’t been blogging much lately. It’s not that I have anything against blogging – I haven’t been doing much of anything lately, unless breathing and digesting count.

In another universe, however, I’ve been blogging up a storm while hiking through Alabama with Gwyneth Paltrow and Vladimir Putin. That’s what many physicists seem to believe anyway. (In that other universe, Vlad promised Gwyn and me that he’s going to stop interfering with Ukraine.) 

For example, Max Tegmark of M.I.T. has written a book that, according to the New York Times, suggests that he was almost hit by a truck while riding his bike in Stockholm, and the truck hit him, resulting in some slight injuries, and the truck really clobbered him, which meant he didn’t live to write the book he later wrote: 

He endured every possible outcome, happy and unhappy, that can befall a bicyclist who encounters a speeding truck. All of these happened, he argues, because everything that can happen does happen — in at least one of an infinite number of universes.

This extremely large set of parallel universes is called the “multiverse”. Our universe, the particular one that I’m experiencing now, in which I’m not pals with Gwyn and Vlad, is merely one universe among many – no more real than the others. 

Very smart people like Max Tegmark and Stephen Hawking accept the multiverse theory, which is also known as the “many-worlds interpretation of quantum mechanics”. They think this apparently crazy idea best explains the truly crazy stuff that happens at the quantum level of reality, like the double-slit experiment and the situation with Schrödinger’s cat. We’ll probably never know for sure, since verifying the existence of another universe is supposed to be impossible.   

Still, something has been bothering me since I read that article in the Times. When people talk about parallel universes, they usually talk about universes branching off from each other. What supposedly happens is that whenever there’s more than one possibility in a given universe, that universe somehow splits into two or more separate universes. You start out in one universe and get hit by a truck but in another universe you escape injury. In one universe, you order pork chops, in another you have a salad and in a third you go somewhere else to eat. The examples in these discussions are almost always familiar events or decisions, the kind of possibilities we can all relate to.

Physicists, however, don’t usually concern themselves with what people have for dinner. Quantum physics, in particular, concentrates on very small-scale events. Will an atom of carbon-14 decay or not? How frequently do quantum fluctuations (the so-called “appearance and disappearance of virtual particles”) occur? In theory, each of these small-scale, apparently random quantum events marks a divergence in the history of the universe. If an atom decays, the universe goes one way. If it doesn’t decay, the universe goes another way. According to the many-worlds theory, as it’s almost always explained, each event that could have happened differently results in the creation of separate universes.

Of course, since the universe is a very big place, there is room for lots of events to occur, especially the tiny, random ones. Here’s a quote from The Many-Worlds Interpretation of Quantum Mechanics by the physicist Bryce DeWitt: 

This universe is constantly splitting into a stupendous number of branches, all resulting from the measurement-like interactions between its myriads of components. Moreover, every quantum transition taking place on every star, in every galaxy, in every corner of the universe is splitting our local world into myriads of copies of itself [161].

Wow! Is it really possible that equally gigantic, almost exact replicas of the universe, with all its particles, planets, galaxies and so on, are springing into existence zillions of times a second, whenever a sub-atomic particle somewhere in the universe sneezes? And that those replicas immediately start replicating themselves? As that old TV commercial said, that’s one spicy meatball!

The effect seem way, way, way out of proportion to the cause. Where does all the energy come from to create fully-formed copies of previously existing universes? Assuming that these new universes immediately pop into existence, how do they get so big and so detailed so quickly? Or maybe universe creation takes a long “time”, but we don’t notice any breaks in the action because we keep coming into existence with our memories and instrument readings intact, as if nothing weird has happened (remember that you and I have lived through zillions of such universe creations – it’s not as if we’ve always lived in the nice, stable universe and everybody else is off living in copies).

I don’t know enough math or physics to criticize the many-worlds theory for real, but I was pleased to see that one of the things bothering me is a standard objection to the theory. From Wikipedia:

Conservation of energy is grossly violated if at every instant near-infinite amounts of new matter are generated to create the new universes.

To which, proponents of the theory are said to have two responses:

First, the law of conservation of energy says that energy is conserved within each universe. Hence, even if “new matter” were being generated to create new universes, this would not violate conservation of energy. (That doesn’t seem like a very good answer to me, since it amounts to saying, “It’s very strange that there’s an exception to this fundamental law, but that’s what happens”.)

Second, conservation of energy is not violated since the energy of each branch has to be weighted by its probability, according to the standard formula for the conservation of energy in quantum theory. This results in the total energy of the multiverse being conserved. (Which seems to mean that if there’s a 50/50 chance of some atom decaying, each new universe has half as much energy as the last one. Wouldn’t that eventually result in new universes having no energy at all?)

So it was with some relief that I turned to a helpful website called “Ask a Mathematician”. It should really be called “Ask a Mathematician or Physicist”. because it’s apparently a mathematician and a physicist answering questions, most of which have to do with physics (they don’t identify themselves, they just answer questions). A few years ago, they got this question:

According to the Many Worlds Interpretation, every event creates new universes. Where does the energy and matter for the new universes come from?

Here’s some of the physicist’s (rearranged) answer:

If you go online (or read some kind of book or something), you generally find the Many Worlds Interpretation presented as the universe “splitting”. Something along the lines of “everything that can happen will, just in different universes”. Supposedly, every time any kind of quantum event happens that could have one of several results (which is essentially every moment for every thing, which is plenty) the entire freaking universe splits into many universes. But, the universe contains a lot of energy….So, whence does this energy come?

[However,] there is no new energy or matter (or even new universes)…The universe doesn’t split or spawn new universes…. The universe doesn’t branch so much as it meanders and intertwines….If you want a picture to work with, rather than thinking about the universe as an ever-branching tree, think of it as an intertwining (albeit, very complex) rope.

The many (like: many, many) different versions of the universe branch apart, and come together all over the place. That is: one event can certainly lead to several outcomes, but in the same way, several causes can lead to the same event.  Everything that could happen will happen (given the present) and everything that could have happened did happen (given the present)….

A particle comes along with some amount of energy. When it has a choice of two paths it takes both.  The energy of the particle is divided in proportion to the probability of the path taken.  So, for example, a 50% chance of each path means equal division of the energy and matter of the particle.  Before the fork all of the energy is on one path, and afterwards, despite the fact that the particle is behaving as though it’s in two places, the same amount of energy is present, just spread out.

So, while it’s fun to talk about “other quantum realities” and “different universes”, it’s more accurate to say that everything is happening in one universe. One, stunningly complex, weirdly put together, entirely counter-intuitive universe.

Clear? Despite the standard explanation, we’re all living in the same universe, but it’s a universe that has lots of its contents in strange, probabilistic quantum states. Since these various states (like when a photon is 50% likely to be here and 50% likely to be there) are equally real, they can be thought of as parts of different universes, but that’s just a manner of speaking.

Whether or not this way of understanding the multiple universe theory is correct (is it, since Max Tegmark apparently suggests otherwise?), it makes me feel better. For one thing, it’s less mind-boggling. Big branching universes seem both implausible and terribly wasteful. Secondly, I think there’s zero probability that one of me is hiking through Alabama with Gwyneth and Vladimir (while wearing a blue shirt, and a red shirt, and a green shirt, and no shirt, etc. etc.) while also breathing and digesting here in the Garden State.

(Note, however, that if the universe is infinite in time and space and configured a certain way, it’s possible, maybe even a sure thing, that everything that isn’t contradictory happens over and over again. But that’s something to wonder about another day.)

How the Universe Got Big

A team of radio astronomers, working in Antarctica, where the air is clear and dry, have found the first direct evidence for the theory of cosmic inflation. That’s the theory about the origin of the universe first stated by the physicist Alan Guth in 1980.

Here’s some background from an article Guth wrote in 1997 for Beam Line, the magazine of the Stanford Linear Accelerator Center (now the SLAC National Accelerator Laboratory):

Although it is called the “Big Bang theory,” it is not really the theory of a bang at all. It is only the theory of the aftermath of a bang. It elegantly describes how the early Universe expanded and cooled, and how matter clumped to form galaxies and stars. But the theory says nothing about the underlying physics of the primordial explosion. It gives not even a clue about what banged, what caused it to bang, or what happened before it banged. The inflationary universe theory, on the other hand, is a description of the bang itself, and provides plausible answers to these questions and more.

Guth explains that in order for the universe we observe to have begun with a Big Bang, the early universe must have been extremely uniform and have had a precise density. However:

The classical form of the Big Bang theory requires us to postulate, without explanation, that the primordial fireball filled space from the beginning. The temperature was the same everywhere by assumption, not as a consequence of any physical process….

[In addition] the initial values of the [universe’s] mass density and expansion rate are not predicted by the theory, but must be postulated. Unless we postulate that the mass density at one second just happened to have a value between 0.999999999999999 and 1.000000000000001 times the critical density [the boundary value between a universe that will expand forever and one that will eventually collapse], the Big Bang theory will not describe a universe that resembles the one in which we live…

Although the properties of the Big Bang are very special, we now know that the laws of physics provide a mechanism that produces exactly this sort of a bang. The mechanism is known as cosmic inflation.

The National Accelerator Laboratory issued a press release today:

Instead of the universe beginning as a rapidly expanding fireball, Guth theorized that the universe inflated extremely rapidly [faster than the speed of light] from a tiny piece of space and became exponentially larger in a fraction of a second.

For inflation to occur, the universe must have been in a state that allowed a sudden change to release enormous energy, creating an expanding universe almost from nothing. The process was apparently a kind of delayed phase transition, as when water is supercooled below its natural freezing point and then, because of some disturbance, suddenly freezes, generating heat.

However, as Guth immediately realized, certain predictions in his scenario contradicted observational data. In the early 1980s, Russian physicist Andrei Linde modified [the theory so that it] generated predictions that closely matched actual observations of the sky.

The new observations reported today are the first evidence of the existence of gravity waves. These are ripples in spacetime originally predicted by Albert Einstein. The radio astronomers working in Antarctica found traces of these ancient gravity waves by analyzing the cosmic background radiation left over from the Big Bang. Andre Linde reacted to the news: “These results are a smoking gun for inflation, because alternative theories do not predict such a signal. This is something I have been hoping to see for 30 years.”

Future Nobel Prize-winner Alan Guth offered this summary in 1997:

While it may be too early to say that inflation is proved, I claim that the case for inflation is compelling. It is hard to even conceive of an alternative theory that could explain the basic features of the observed Universe. Not only does inflation produce just the kind of special bang that matches the observed Universe, but quantum fluctuations during inflation could have produced non-uniformities which served as the seeds of cosmic structure [in particular, the existence of galaxies].

Physicists doubted whether Guth’s theory would ever be proven. With today’s announcement, cosmic inflation is a big step closer to becoming settled science.