The physics of portals

Fuckin' portals - how do they work?You heard it like me, someone just asked about the physics of Aperture Science's neat Portal Gun. I'll try to give an account of what we know from the material that Aperture recently made available and from what can be deduced from demonstrations of the product.

Unfortunately I've been unable to get any additional information or confirmation of my findings from Aperture themselves as the only person I was able to contact, a Mrs. Glados, told me on the phone that "all the persons who are still alive are currently unavailable, but as you seem to have an interest in doing science, I'd be happy to show you around our test chambers. We are open 24/7. I hope you like orange. Can you bring some cake? I don't want to lie to you: we seem to have run out."

So let's get going, shall we? Here's how the gun works:

The Portal Gun (source Aperture Science)

The central part of the Portal Gun is a miniature black hole with a Schwarzschild diameter of a few centimeters. Now black holes this size usually radiate strong amounts of Hawking radiation, resulting in their rapid evaporation. This is counterbalanced by an extraordinarily simple device, in the form of a cooling fan that blows evaporated virtual particles back onto the black hole's horizon.

Above and below the black hole, there are two ring singularity rings that can be made to rotate one way or another in order to communicate angular momentum to the black hole (this is why operating the gun while moving creates the impression that it is being gently pulled out of your hands, by gyroscopic effect). Making the hole rotate results in the event horizon opening up and revealing the ring singularity inside.

The fan is then sped up suddenly behind the singularity to blow part of it forward into the portal intake manifold, focused by the three quantum shaping prongs that you can see moving around the front end of the gun when firing a portal. The focalization is necessary but not sufficient, as the singularity needs to be stopped by a surface charged with Z bosons. This is why Aperture is building special panels for their test chambers, the only surfaces that can stop portals in place. Whenever you attempt to fire a portal on a different surface, the portal continues its course through space unaffected while the dye is stopped by the wall and produces a spray of color at the impact point. This of course makes portal guns unusable in practice outside of a specially equipped test facility.

It's worth mentioning at this point that it is a trivial cosmetic detail that orange or blue dye is injected around the singularity at the precise moment when it passes through the intake manifold. The dye then enters into the gravitational orbit of the ring singularity and remains there as long as the portal remains active, creating the rotating colored shimmer that we all know and love.

Now here is the tricky part: when you fire the second half of the portal, it is emitted as a second ring singularity that rotates counter to the orientation of the first one and most importantly while being entangled with it. It is this quantum gravitational entanglement that does the job of bridging space-time on both sides of the portal. Contrary to common belief, Aperture's portals work by creating a quantum tunneling channel between two locations and not at all by creating a wormhole. Creating wormholes requires considerably more energy, making the process unsuitable to the construction of portable devices. Furthermore, as Black Mesa recently showed, we do not know how to control which universe the other end of the wormhole comes from.

It is often asked whether portals are limited to connecting points in space or if they could permit time travel like wormholes do. Well, if you can find a way to aim in the direction of the past or future, which are unfortunately orthogonal to the three dimensions of space that we are familiar with, then yes, it is possible. Good luck with that.

Now that we understand how the gun works, we can look at the energetic consequences of punching tunnels into space. One thing that all people who have operated a portal gun report is that if they create a portal between two places that present a potential gravitational energy gradient (in layman terms, different altitudes), there is wind coming out of the top portal and entering the bottom portal. This wind gets stronger with the altitude difference.

This is very easy to understand as the difference in potential energy between the two ends of the portal manifests itself like any potential energy gradient: by a force from highest to lowest potential.

That leads us to an interesting point which is that air is affected by portals in exactly the same way that we or any massive object such as a weighted cube is. If for example you punch vertically aligned portals on the floor and ceiling of a test chamber, the air in the room will start falling through, creating a strong wind that will blow downwards, attracting passers by in virtue of the Venturi effect.

Another amusing consequence is that falling through such a portal pair, you can reach speeds much higher than the normal terminal velocity in the same conditions of pressure and temperature.

A gravitational turbine, as used by Aperture ScienceThis effect is actually used by Aperture Science to produce the considerable energy that their testing facility consumes: weighed cubes are left to fall between two portals in a tall well, and a turbine harvests the gravitational energy transformed into kinetic energy along the way.

Now of course the next question is where does this energy come from? Well, the portal itself carries little energy and it doesn't seem to decay as energy is harvested. Many speculations have been made about this but the most plausible explanation seems to be as follows.

Conservation of energy, as everyone knows, is not a principle in itself but rather is a consequence of the laws of physics being the same at all points in time. Ergo, all you have to do is to break the laws of physics in order for energy to stop being conserved. And you'll have to admit that a persisting quantum tunneling device is as weird as it gets.

The effect of this is that constants such as the fine structure constant or the gravitational constant are probably varying slightly as more stuff gets dumped into portals, possibly resulting eventually in atoms failing to retain electrons, galaxies to dissolve or the Sun to transform into a black hole. But don't worry too much, that should take at least a few centuries to happen if my calculations are right.

Well, this is it in a nutshell. I'm going to take questions now.


Rees, ethics, aesthetics and religion

Sir Martin Rees said this right after receiving a huge pile of money from the Templeton Foundation:

[…]I think just as religion is separate from science, so is ethics separate from science. So is aesthetics separate from science. And so are many other things. There are lots of important things that are separate from science.

"Just as"? When is the last time you heard a philosopher of ethics or aesthetics make a claim about the origin of life or of the universe? Or, for that matter, make any claim that directly contradicted hard science?

This insistence that religion and science are non-overlapping magisteria is decidedly strange. Science's magisterium is very clearly defined: it's everything that is a natural phenomenon. If religions want to stop overlapping with that, it's fine by me but are they prepared to do that?


Do not reward luck

Dead monkeyHere is a little experiment. I have built a bunch of programmed agents that are using a variety of strategies to try and predict the outcome of a randomized event. The event in question is the roll of a dice. The twist is that the probabilities of all sides of the dice are not equal: there is a distribution of probabilities that is itself decided randomly before the experiment.

Here is a table showing how well each of the agents did on a hundred throws of that unfair dice:

  • Agent 1: 18
  • Agent 2: 22
  • Agent 3: 20
  • Agent 4: 10
  • Agent 5: 14

Assuming you can't make any further tests, which agent would you hire to predict future throws?

The correct answer is none of them: you just don't have enough data. So let's throw the dice an additional thousand times:

  • Agent 1: 180
  • Agent 2: 188
  • Agent 3: 176
  • Agent 4: 136
  • Agent 5: 168

What can we notice here? Agent 2 still seems to be doing pretty well, and agent 4 is still doing poorly, might you say. Well, that's true but irrelevant.

What you should be noticing is that the average probability of a hit over all the agents and over all the throws we've made is 0.169. But wait a minute. The probability of a completely random number between 1 and 6 is 0.167. That's pretty close. Just way too close to be a coincidence, as additional data would confirm.

You should by now have understood that I lied: that dice is not weighed at all, the numbers are as close to random as I know how to make (I used crypto-random numbers).

Our five agents do have various strategies (ranging from always picking the same number to picking the number that came out most often in the past) but the point is that it doesn't matter. There is no way to predict a random phenomenon (otherwise it's not random). No strategy works. None ever will. They are all equivalent to chance.

Now what am I getting at? The main lessons we can extract from this are the following:

  1. You can usually determine with a good level of certainty whether a phenomenon is random by confronting its statistics with something you know to be random (it's sometimes trickier than that but is mostly reliable).
  2. Luck in the past is not an indicator of luck in the future. Do not reward it.
  3. In order to distinguish luck from talent, you need to determine first whether the domain where they apply is predictable and only once that's been shown, to consider previous results of the candidate.

To conclude, I'll leave you with this thought. What profession rewards its members with extravagant bonuses whereas it's been shown that dart-throwing monkeys were consistently doing better than any of them in the long run?


Apologetics is not a proper form of reasoning

Apologetics is the systematic defense of a position. It's usually done by religious people in defense of their dogma.

We are all biased, but embracing bias as the starting point of your reasoning is not going to help you find any reliable truth.

Contrast that with scientifically obtained information. All scientists have their own bias, but scientific methods are designed to eliminate that bias. That's what they do: neutralize subjectivity. Imperfectly, but better than anything else we know. As a consequence, they are our best chance to discover objective truth.

When a new idea emerges in science, the very first thing scientists do is attempt to destroy it. That is not in defense of any kind of orthodoxy, it's to verify that the idea really is a good.

Can apologists reach any form of truth? They could, by chance, but even if they did, what they find would be of no value until it's been scrutinized and verified by a wide community of independent researchers. Why not start with that? Are you interested in finding the truth or in defending your position?


“One cannot prove a universal negative” Oh really?

The Mad Hatter stuffing a teapotThis is a claim I've read so many times in comments that I think it deserves a little debunking. If you do a search on that little sentence, you'll see that it's very rarely if ever used in a scientific context but is repeated like a mantra by religious apologists. They seem to be persuaded that it is an established rule of logic.

Let's get it out of the way: it isn't. Here is a counter-example:

No even number that is larger than two is prime.

Done. I hope you'll agree that the proof to this is trivial.

One can prove a universal negative. Declaring otherwise pretty much constitutes a logical fallacy in itself. A universal negative poses no logical challenge whatsoever.

Now this of course applies to mathematics. When it comes to empirical truth, the challenge is quite different: one doesn't deal with proof whatsoever. Instead, you deal with evidence, no amount of which is ever equivalent to proof. Some assertions can be backed with more or less lines of evidence of various quality, which does make some assertions more valuable than others. But proof? Nope. Never. No big deal, too.

Apologists who resort to this false argument might as well say that science cannot prove anything. No it can't. Nor does it ever claim to.

But the absence of proof for not A does not mean that A, let alone B is true. The absence of proof for the non-existence of God does not mean that the Abrahamic God, or Zeus, or the Flying Spaghetti Monster exists. The absence of proof for the absence of a teapot orbiting the Sun between the Earth and Mars does not mean that there is a red teapot there.

Believe what you will. But if you are going to argue for your belief in scientific-sounding terms, or if you make claims that overlap with science (which all religions do), be prepared, and avoid making stuff up. Oh wait...


Stephen Hawking's The Grand Design

A model of the universeMany silly things have been written and said about this book, mostly by people who haven’t read it. Too bad, it’s a very short and easy read...

The central claim of the book, the one on which the marketing campaign has been centered, is that God is not necessary in order to explain the universe. That’s nothing new: when Napoleon asked Laplace about two hundred years ago why he wasn’t mentioning the Creator in his work, he famously answered:

“I had no need of that hypothesis”

In 1670, Spinoza also hypothesized that the world could be understood without God having to play any role in it.

Hawking’s claims are not very different. Never in the book does he say that there is no god. This hasn’t stopped most clueless commenters to assume that he did but he simply did not. Concluding that God exists or not is left as an exercise to the reader. The shrinking relevance of the concept is of course nothing new, it has been going on for centuries but the erosion has never seemed to be an obstacle to the true believer.

To be fair, there are jabs at religion in the book (which is not the same as jabs at God), such as this one:

“In 1277 Bishop Templier of Paris, on the instructions of Pope John XXI, published a list of 219 errors or heresies that were to be condemned. Among the heresies was the idea that nature follows laws, because this conflicts with God’s omnipotence. Interestingly, Pope John was killed by the effects of the law of gravity a few months later when the roof of his palace fell in on him.”

What Hawking does claim is that the relatively recent discovery that the total energy of the universe is zero, coupled with the existence of a law such as gravitation, are enough to explain the creation of our universe. There is actually not much here that isn’t already familiar to people who have been following the progress of physics.

Many commenters have pointed out that he doesn’t explain why there is a law of gravitation. Well, they either haven’t read the book or haven’t been paying attention. He does give an explanation, which is that a quantum cosmological model such as the one from superstring theory he’s using, has to include all possible physical laws. Still, I would agree with those commenters that he’s not going deeply enough to explain the origin of physical laws. That doesn’t mean that there are no naturalistic explanations, just that the book does not provide a fully satisfactory one. In that way the central claim of the book is a little overblown as it really only pushes God into a smaller gap.

Hawking in general does not enter into too many details and that would be my main grief against the book. There is a lot of hand-waving going on, which too bad as the science behind what he’s saying is worth explaining. Because he doesn’t explain, many readers may think he’s just making things up.

There is an insistence in the book on adopting what the authors call model-dependent realism, which is a philosophical parti-pris that because all we know of reality is through our sensations, we cannot have tests of reality that are completely independent of the models we build to account for observation. This is actually not very controversial but it has already been misinterpreted by the likes of Deepack Chopra as validation of their own crazy ideas that the mind was somehow creating reality. Hawking could have been more precise: he could have predicted that pitfall and avoided it by clearly stating what he was not saying.

I’ve been focusing in this review on the negatives (oh, did I mention the lame attempts at humor that could have been entirely avoided?). Still, I recommend the book as the positives vastly outweigh my nitpicking. It is a good and pleasant read. It does present solid arguments (although they could be supported by more actual scientific contents) and does push back the role of God in creation. It is also a good introductory text for those who want to understand the current state of cosmology. A modern and honest person should read it, if only in order to be able to speak of it intelligently.


Faster than the wind

SailboatThere is a vigorous debate going on about whether it’s possible to build a vehicle that uses only wind power to accelerate to a speed that is higher than the speed of the wind and in the same direction as the wind itself (a phenomenon referred to as Downwind Faster Than the Wind or DWFTTW). You can see a summary of the debate here and a video of an actual cart going at 2.8 times the speed of the wind here.

It’s quite amazing and counter-intuitive that it works, but it seems to, beyond the shadow of a doubt. It’s so amazing that lots of people still refuse the evidence, and the whole thing has been declared impossible by more than one physicist based on energy considerations.

Well, those energy considerations are misguided as I hope to show in an extremely simple way. Actually, the whole thing has very little to do with energy (the wind is providing plenty of that) and everything to do with simple mechanics. Actually, once you’ve wrapped your head around it, it’s quite breathtaking that such a simple idea wasn’t discovered before.

In order to understand a problem, it’s useful to simplify it and reduce the number of variables to a minimum. In this case, the lossy nature of the forces between the cart and the wind is a complicating factor.

As a simplification, I will make the whole system perfect. I will replace the wind and the ground with solid racks and the propeller and wheels with gears that are bound together and that are constrained to move only horizontally:Faster Than The Wind Made Simple

It’s a good way to visualize the forces and constraints of the system if it were perfect and to understand how it has to work.

Let’s first constrain the top rack (the wind) to be stationary and the ground to start moving to the left. The bottom gear, which is constrained to only move horizontally, seems to have only one choice: it can only start rotating clockwise.

Now if the bottom gear rotates clockwise, then the top gear will have to follow and start rotating counter-clockwise. And the only way it can do that is by moving to the right. Now what enables the wind and ground to move relatively to each other is that the bottom gear is made from two gears so that the speed of the teeth of the outer gear is higher than the speed of the teeth of the top gear.

The inevitable conclusion is that the whole gear system will have to move to the right with a speed that is determined by the speed by which the ground is moving and by the ratio in the sizes of the gears.

By a simple change in referential, the exact same system but where the ground is fixed and the wind is moving to the right, it should be clear that the whole system has no choice but to move to the right faster than the wind.

In summary, there is only one solution for this constrained system, and it implies the gear system to move faster and in the same direction as the top board.

QED. Now the only difference between this and the real wind-based system is that the latter is much lossier and far from perfect. Still, it has no choice but to pick up speed and get faster than the wind.


What that guy believes

Fig. 68Michael Egnor has now answered his own questions so we can now review his answers and discover in amazement how they make a lot more sense than what non-theists and scientists could come up with. Or not. His new post can be found here. My own answers to those same questions can be read here.

The first thing I noticed in Egnor’s new piece is that while atheists are often accused of arrogance, Egnor also assumes that they are ignorant:

“these explanations have largely been forgotten by atheists and by scientists with a dogmatic materialistic view of nature”

They have not been ignored of course, they have just proven to be useless or obsolete and it’s the likes of Egnor who have been largely oblivious of the progress of science over the last centuries. Which is why they clutch at multi-century-old notions that the rest of the world has dismissed for good reasons.

“Dogmatic”? How pretentious! The essence of science is to be the opposite of dogmatic thinking. It is a set of methods that we have devised in order to discover truth about the natural world despite our preconceptions thereof. Scientific thinking cannot be dogmatic, otherwise it’s not scientific. It’s a common technique to accuse your adversary of your own faults so this is hardly surprising from the apologists of Dogma.

Also make note of the pretensions of Egnor:

“these beliefs are entirely compatible with modern science; in fact, classical philosophy and classical theism is the source for modern science”

We’ll see about that...

1. Why is there anything?

“God created the universe as a free act of creation. God is Spirit and is not created; The Thomist paradigm of essence (what a thing is) and existence (that a thing is) can be applied by analogy to God: God's essence is existence. His existence is necessary.”

That is an entirely circular definition of God. It is essentially different from my own argument which was based on the intrinsic existence of real mathematical objects that have a rigorous definition. The argument from instability of nothing also is a well-established discovery of 20th century physics.

Hand-waving and play on words on the other hand are not considered a proper form of reasoning. The only thing whose essence is existence is existence itself. Not God. You might as well say “the essence of the universe is existence. Its existence is necessary.” The reasoning isn’t any more valid but there is at least one thing that is verifiable in there. Not so of Egnor’s argument.

2. What caused the Universe?

“1) Whatever begins to exist has a cause 2) The universe began to exist 3) The universe has a cause. A super-natural cause in necessary for the creation of nature ex-nihilo. 'Nature created itself' is nonsense- it's a contradiction. From nothing comes nothing.”

Again, Egnor demonstrates his ignorance of modern science. Causality is a notion that presupposes time, which may not have existed as we know it at the “beginning” of the universe. The argument that everything has a cause only applies to the contents of a universe where causality exists, but not necessarily to the universe in its entirety nor to any kind of universe. It’s hard for us to imagine anything else, because our whole existence would be impossible in a universe that wouldn’t have causality, but it isn’t otherwise a necessity and in particular it probably breaks down near the “beginning” of the universe. It’s also assuming there needs to be something outside of the universe. A real Universe is entirely self-contained: by definition it’s the total sum of everything that exists. We can conceive in cosmology of universes that have no boundary and no beginning, just a smooth form. Think of a sphere (which we know how to construct without plunging it into a 3D space by the way). Where is the beginning of the sphere? There is no such thing. Any definition of one is arbitrary.

Also, from nothing comes something all the time, everywhere. Another discovery of 20th century science was that void is unstable. Combine that with a force like gravity, which has negative energy, and you have the absolute necessity for a material universe to emerge.

Finally, please show me the cause for the existence of the mathematical group Z2.

Egnor is almost right on one thing though:

“This Pure Act is uncaused, beginningless, changeless, immaterial, timeless, spaceless”

Replace “Pure Act” with the universe and there you have it: a modern view of the universe. Except for one essential difference: modern cosmology is based on and verified by observation, whereas Egnor’s Pure Act is just hand-waving.

3. Why is there regularity in nature?

“Teleology is the goal-directedness of nature.”

There is no such thing as the goal-directedness of nature, except in the twisted minds of ID-proponents.

4. Of the four causes in nature proposed by Aristotle, which are real?

“the four causes were truncated to two or three by enlightenment philosophers, who didn't like the theistic implications of classical philosophy […] Moderns generally don't understand any of this, and accept merely material and truncated efficient causes as adequate to describe nature. They are mistaken.”

It’s not that they didn’t like them. That does not matter in the least. What matters is that they discovered that the harder they looked, the less final causes seemed necessary (science does not bother with unnecessary hypotheses, as famously illustrated by Laplace). Worse: they were counter-productive in that they were getting in the way of finding objective truth. This is all very well understood and not the product of ignorance. Quite the contrary.

5. Why do we have subjective experiences?

“humans have spirits, which are created in God's image. We are subjects and not just objects because of the powers of our rational souls and the fact that we are spiritual creatures. […] Nothing in materialism predicts or explains the emergence of 'I' from 'it'”

Again, failure to recognize the achievements of science and even philosophy. For instance, read Nietzsche and his idea of consciousness as a grammatical fiction or Hofstadter’s I am a strange loop. Neuroscientists have been able to study the brain with ever-increasing precision and have obtained some extremely curious and important results, such as consciousness of an act happening after the act is performed, reversing our assumption on which causes which. The way consciousness, sensations, feelings, states of mind, memories or even religious experiences can be induced or suppressed by physical and chemical stimulation of the brain also point to a materialistic explanation of our subjective experiences. There is plenty of science dealing with the emergence of ‘I’ from ‘it’, and it suggests that our consciousness is more after the fact story-telling than causation and free-will agency.

There is one question I’ve always wanted to ask dualists: where does the soul go when you sleep and when you don’t dream?

6. Why is the human mind intentional? How can mental states be about something?

“Intentionality is no problem from the classical hylemorphic understanding of nature and of man. It is inexplicable by materialism. Materialism, which acknowledges only material and efficient causes, founders on intentionality”

Here, Egnor is lying. He has read Dr. Novella’s answers to his posts on that subject but ignores it.

7. Does Moral Law exist in itself?

“Moral Law is "written in the heart" of men, and each of us feels an obligation to comply with it. […] Moral Law is the manifestation of Divine Law, and compliance with the Moral Law represents a telos (final cause or purpose) of man's life.”

More hand-waving. Here is another thing that is written in the heart of men, quite literally: genetic information, the results of hundreds of millions of years of evolution. Seriously, read Sam Harris.

“if Moral Law doesn't exist independently to men, then it is the moral law of the strongest of men that will rule”

Ah, that old canard that if morality does not come from God, everything is permitted. And that other canard that evolution is about the law of the strongest.

Never mind that the evolution of altruism is well understood since George Price. Never mind that modern evolutionary theories deal with populations much more than with individuals.

8. Why is there evil?

“Evil is the privation of good. It exists because we are a fallen race in a fallen world.”

This, I must say, may be the most disgusting and dare I say evil part of the Christian dogma: that we somehow all have to pay for the Sin of our long-dead ancestors is plainly immoral. Compound that with the nature of the Sin in question and you get a doctrine that I could never, ever swallow (pun intended). There are plenty of very obvious and perfectly good explanations for the existence of evil, and God is not one of them. Quite the contrary, if God were to disappear in a puff of logic (to quote Douglas Adams) it could be from the existence of evil, and Egnor is well aware of it:

“there are still aspects of natural evil (children with cancer, etc) that I find very hard to understand”

Indeed. but he also says:

“The traditional theodicy that natural evil provides opportunity for courage and faith makes sense to me”

What a horrible, twisted way to induce virtuous behavior. Aren’t there ways to inspire courage other than the horrible suffering and death of children? Especially when you are an omniscient and omnipotent being? Does Egnor even realize the enormity of what he’s saying?

“atheism and materialism offer no solutions at all. If mankind evolved by natural selection, we wouldn't even perceive the death of unrelated others as evil. It would be a real win- more offspring for me!”

And once again, we see the use of a straw-man version of evolution that only exists in the minds of ID proponents. See above, this is very well understood.


A few things should be clear from all this.

Far from resulting from ignorance, at least some atheistic views are constructed on the accumulation of centuries of philosophy, science and even theology. They also take into account results from modern science and are open to revision as new evidence is discovered.

Egnor, by comparison, ignores -probably maliciously- centuries of progress. And he doesn’t take comments on his blog, which says a lot about his open-mindedness.

Make your own conclusions...


An answer to what does this atheist believe

TimeMichael Egnor doesn’t know me but as his question seems to be addressed to the community collectively I’ll take the liberty to give my answer here. If you haven’t already, go and read his post first:

What do new atheists actually believe?

Well, I don’t know if I’m new but I’m certainly an atheist.

First a quick answer on Michael’s three assumptions about atheist “cliff notes”:

  • “There are no gods”: yeah, that’s kind of the point of atheism, ain’t it?
  • “Theists are IDiots”: not all of them although some are.
  • “Catholic priests molest children”: some do, that’s fact, right? The Church’s failure to report those to the authorities is also important to point out.

Michael seems to insinuate that is all we ever talk about. Well, what we have here is first what defines us, then the very important issue of science education and finally one of the biggest scandals to touch the Church in recent times. It’s understandable that would take a lot of space on atheist blogs. But the idea that we would never talk about anything else is a stretch.

So on to the questions…

1) Why is there anything?

I don’t know, but I have some ideas. Consider very simple mathematical structures such as the natural numbers or mathematical groups. Those structures exist independently of the universe and of the existence of mathematicians, let alone any divinity. There you have an example of something that exists naturally and spontaneously. Now if you consider more complex structures (even simple concepts such as group theory can summon monsters of complexity) you can imagine that above a certain level of complexity emerging properties could be part of them. An example of emerging properties is space and time emerging from an underlying discrete lattice.

Note that this idea would be rather difficult to test (although one should not underestimate human genius) but it has the advantage of not requiring a supernatural explanation. In answering this question and others, it’s a good first step to determine that there *are* naturalistic explanations even if they are not necessarily supported by evidence (yet). Naturalistic explanations do have this privilege of being immediately more credible than a supernatural one by virtue of being naturalistic, yes.

It is also a recent discovery of science that the total sum of the energy in the universe is zero. It’s been argued that given a set of laws (and laws, as seen above, don’t necessitate creation), a universe such as ours could spontaneously emerge thanks to that property (Hawking’s new book does a fair job at explaining it, but I also recommend some of Lawrence Kraus’ talks). That is a different argument but it is also valid, albeit at a different level.

2) What caused the universe?

It seems to me that the idea of causality implies time exists. When talking about cosmology you can’t treat time this way: time is a property of the universe, not something that exists outside of it. It follows that in order to have causality of any sort, you need the universe to already exist, and you need to be in a part of that universe where time exists.

That in itself a problem but compound it with modern cosmology indicating that the universe probably has no boundary and that time ceases to make sense when you continue in that direction that we call the past. There goes causality.

Even if you accept the notion of a universal time that exists without the universe or if you somehow extend the idea of causation to not rely on the existence of time, there is still no need for a first mover. The universe could continue indefinitely in the direction of the past (assuming that can be defined), or it can have no boundary, but in both cases, why would it need a cause?

3) Why is there regularity (Law) in nature?

I don’t know, but 1) gives a possible answer: it’s the sets of laws that exist outside of our universe and outside of time, and the universe emerges out of what the laws permit.

4) Of the four causes in nature proposed by Aristotle (material, formal, efficient and final), which of them are real? Do final causes exist?

Well, I’m not sure but we’ve learned a thing or two since Aristotle, wouldn’t you say? Ultimately I would say that final causes don’t exist (see above, about time and causality being properties of the universe that don’t apply to it as a whole).

5) Why do we have subjective experiences and not merely objective experiences?

Probably because our consciousness emerges from our brain, which only receives subjective stimuli.

6) Why is the human mind intentional, in the technical philosophical sense of aboutness, which is the referral to something besides itself? How can mental states be about something?

I’m not sure I understand all the implications of the question but maybe because it emerges from sensorial information? What could it be referring to if not something beside itself?

7) Does Moral Law exist in itself, or is it an artifact of nature?

Sam Harris just published a book you might want to read in order to get a much better answer to that question than what I could provide in a blog post. I do believe that there is such a thing as well-being that emerges out of the nature of our bodies and minds. From that you can define the Golden Rule (which all human societies have done independently) and the rest is refinements from that. Some of those refinements are justified by how natural selection modeled us, yes.

8) Why is there evil?

You first need to define evil. Let’s say we define it as deliberate causation of harm. Then there are a variety of possible causes for it: greed, past traumas, psychosis, religious indoctrination, etc. I’m not sure how that question is very puzzling unless you believe in an omnipotent and universally good god.


How the hell do we know?

Fig.8I was once asked “Why do you believe the Earth to be revolving around the Sun, and not the other way around?”

Here’s the answer I gave:

I don’t. Let me explain.

Imagine for a second that the Earth and Sun are the only massive objects in the Universe. If you are an observer on the surface of the Earth, you might feel that this description is less useful than the one centered around exactly where you are: you look at the sky and see the Sun going roughly in circles around you. That is, until you look a little more closely and you notice that the circles move with the seasons. That’s fine, you can take that into account by introducing perturbations of sorts into the trajectory of the Sun and find a reasonably simple equation that seems to account for it. You still have no explanation about what's going on, but at least you are getting closer to a predictive model. You can start wooing the rest of your tribe by predicting the next eclipse for example. Oh wait, we haven't even put the Moon into the universe yet. Hold on, we will in a second.

Let's not bring planets and satellites into the picture yet, but let's add the rest of the universe. Now we have stars in the sky that appear like a sphere with some bright dots on it and that rotates around us. To the naked eye, this is a very stable object that moves in a very simple way. It looks perfect and eternal, except for the occasional supernova. And it looks very much like we are at the center of it. That is, until you look with a big telescope like Bessel did in 1838 and make measurements of star positions at different times of the year precise enough to notice that only some of them move with the seasons, and some others, such as Sirius, wobble over a few decades (another one of Bessel's discoveries). But let's assume you don't have access to a big telescope and that you don't know that.

So let's bring the Moon in now. That is an object that has many striking features but it is yet another object that is just going in circles around us. Because it occasionally passes in front of the Sun, we know that the Moon is closer to us than the Sun. The phases of the Moon show us that it is a sphere that gets lit by the Sun differently as it revolves around the Earth. Good.

But there is another interesting observation that you can make at this point: tides are synchronized with the trajectories of the Moon and Sun: the tides are the strongest when the Moon and Sun are aligned with the Earth, and the weakest when the Moon, Earth and Sun form a right triangle with the Earth at the right angle. That gives us a first hint at an influence at a distance of the heavenly bodies onto Earth-bound objects.

Now's the time to bring the rest of the solar system in. To the naked eye, we have new dots of light that don't behave like the other dots of light: they are moving relative to the background of dots, but all roughly stay on the same circle that the Sun is moving along. But whereas the Sun is moving steadily along that circle, the new dots don't. Two of them wobble back and forth around the position of the Sun, while the others go all the way around but not at a steady pace, even reversing direction sometimes.

Notice that so far we've only used observations that anybody can reproduce with a pair of eyes and optionally some modest travelling around the world and a small telescope.

So how do we interpret that data?

We can try to fit it with a set of functions, which is more or less what epicycles were used for. It does work to a degree, and when the precision of the model is not good enough, we can add more and more epicycles and get closer to the data. That does have a predictive virtue, but all it proves is that the movement of celestial bodies is smooth and regular: you can actually fit any smooth function with a composition of elementary ones. That’s basic mathematics. For example, any sound can be approximated with a series of harmonics, and the more harmonics you add, the closer you get to the original sound. The difference here is that we're talking about the music of the spheres instead of actual sounds.

Nothing in all this of course explains where the epicycles come from.

Now let's shift perspective and imagine that the Sun doesn't move (much) and that everything else but the background of stars -including the Earth- rotates around it. If you get the distances right, the very complicated movements of the planets become ellipses around the Sun, ellipses being about the simplest shapes after a straight line and a circle. You can now get a much closer fit to the actual movement of planets, with a much simpler model. That's what Kepler did in 1605. But you don't have to take his word or any scientist's word for it: it's easy to build a computer simulation of that model that computes the position of each planet in the heliocentric referential and then translates the positions back into geocentric coordinates. You can then compare the results with what you see in the sky.

At this point, we have successfully decomposed what seemed like very complex trajectories into a composition of simple elliptical trajectories: that of the Earth and that of each other planet. Divide and conquer.

We still don't have an explanation of the ellipses though. It took the genius of Newton to come up with that. He single-handedly invented infinitesimal calculus (at the same time as Leibniz) and applied it to expose the laws of motion and then discovered the law of universal gravitation. With those tools, he was able to further reduce Kepler's results and laws to one single law: all bodies in the universe attract each other with a force that is inversely proportional to their distance and  proportional to each of their masses.

Not only does this explain all of the data we've talked about so far (including tides), it also unifies the fall of earthly objects with the movement of planets. Furthermore, it accounts for the movements of the Moon and the satellites of Saturn and Jupiter, two "mini-solar-systems" in orbit around the Sun. By the way, imagine if intelligent life were to evolve on a satellite of a giant planet: their inhabitants would have an even harder problem to solve than ours as they would have to untangle the composition of three orbital movements instead of two.

An interesting remark to make at this point is that Newton put the final nail in the coffin for the geocentric view of the world, but he also was the first to point out that his own theory made the heliocentric view inexact as well: the static point in his model is the center of mass of the whole Solar System, not the center of the Sun. And now we know even that is false as the Solar System moves relative to the center of the Milky Way, which itself moves relative to the local group. More than that, we know that there is nothing special with regards to the physical laws of gravitation about the center of the Sun or the center of the Earth: the physical laws are the same in both points, and we know how to describe the system from both referentials (although one description is simpler than the other, they are two views on the same reality). That is not to say that choosing the geocentric referential is not useful, interesting or efficient to solve a whole class of problems, but if your goal is to understand the movement of planets and stars, it’s not the most efficient and has actually been in the way of figuring it out for many centuries.

The law of universal gravitation enables us to make calculations on the evolution of a system with any number of masses and to go beyond the approximation provided by Kepler's laws. It's been so efficient that with just that tool and the observation data of planet trajectories, which had some anomalous divergences from what Newton's theory predicted, Le Verrier was able to predict the existence and position of a new planet, Neptune, before anyone had seen it. And sure enough, when astronomers pointed their telescopes in the direction given by Le Verrier, there it was.

So to summarize what happened here, scientists were seeing a deviation from the theory, and that could mean three things.

First, that the observations were wrong. That can happen, and the normal procedure is to repeat the observations by as many independent observers as possible. The observations were right.

Second, that the theory was wrong. We'll see something like that happened a little later.

Third, that the anomaly resulted from the perturbations within the theory of an as yet unseen object.

Le Verrier tried the third hypothesis and deduced from it the existence of Neptune. All that had to be done was to check against observation, and the planet was discovered (and Newton's theory confirmed once more).

Encouraged by this success, Le Verrier tried to apply the same method to another anomaly: the orbit of Mercury. He also predicted the existence of a planet between Mercury and the Sun that could account for the perturbations, but this time no such planet was observed. This time, we were in the second case, and it wasn't until Einstein came up with General Relativity that it was confirmed and that Newton's theory was replaced.

This is a great illustration of how science works: observation is the ultimate judge of the validity of a theory. Not common sense, not faith, not hearsay, not authority, not personal preferences. Reality doesn't care what we believe.

So to get back to the original question, no, I do not believe that the Earth revolves around the center of the Sun. I know that the law of universal gravitation -or General Relativity if you need the extra precision- is the most efficient way of explaining the movements that we observe in the Solar System. I know it because I can and have verified it and because innumerable people have done so as well, independently and consistently. I have actually verified myself quite a lot more than that about gravitation when I was a PhD student in a General Relativity lab.

You can also verify it yourself with little effort: grab one of the available open source astronomy programs or solar system simulators out there and look at their algorithms. Then take one of the predictions it’s making about the position of a planet in the sky for tonight and check it for yourself.

This brings me to an important point. While observing the skies is within the reach of almost anyone (I'm saying "almost" because I live in Seattle), verifying all scientific results yourself is impractical when not plain impossible. So how do we know something without having to rely on some form of authority? That is of course a very relevant question that all scientists must have asked themselves at a point of their career (hopefully at the very beginning). The answer to that is that the principle that a scientific assertion can be verified independently is absolutely essential. You cannot qualify a result as scientific unless it is verifiable and falsifiable. And it’s not going to be trusted until it has actually been independently verified. Yes, I’m saying that you have to evaluate and verify scientist’s claims. You absolutely have to. That’s the point. There’s no science if nobody does.

Of course, that doesn’t exclude the possibility of error and fraud, but it provides a set of tools that while imperfect is very efficient and powerful. The scientific community is so large that all results, especially the spectacular and important ones are going to receive lots of scrutiny. They’re going to be challenged in every way people can think of as the reward to overthrowing a previous result grows with the exposure that result has received. That is why Einstein’s glory is greater today than Newton’s.

Don’t get me wrong, there are cases where scientists benefit professionally from defending the status quo, but those can’t stop good new science from appearing and from eventually prevailing.

This is why I trust scientific results more than our primate’s intuition that would have me believe that the Earth doesn’t move, that there’s a point in playing the lottery or that an electron can’t be at two places simultaneously.