In recent discussions I have often encountered the question of what is the best way to establish the truth. Generally this question is used as a cover for religious people to reject the findings of science because they claim science can’t discover certain types of truth and that alternative methods must be employed instead.
Before even examining that issue we must face the problem of is there really a thing called “truth” anyway? Maybe there is no truth at all (a type of epistemological or ontological nihilism), or maybe there are multiple truths depending on your philosophical approach (relativism), or maybe there is a truth but we can never know it for sure (classical skepticism).
Philosophers can debate these problems of epistemology for as long as they like. I fully understand that we can never be totally sure about anything regarding the nature of reality but I prefer to take a more pragmatic approach. We all act as if there is a reality and that we can know it to some extent so let’s keep the whole debate reasonable and start with the assumption that there is an underlying reality and that we can know something about it even if we can never fully understand it.
The scientific method has emerged over the last couple of hundred years as the way to do this, at least in my opinion, but not according to everyone as we will see later. This method is basically a cycle of formulating an hypothesis to test, creating an experiment (using appropriate blinding, baseline testing, controls, etc) or making an observation to test the hypothesis, carefully examining the results, writing up the method and conclusions in a formal way, having other people repeat the experiment, and looking for consistent outcomes and establishing theories based on those.
I would assert that the method works for two reasons: first, it just simply makes sense that it should because careful formulation, testing, and repetition is just naturally a logical way to proceed; and second, it gets results.
Yes, science does get results. We can look at the outcome of science-based interventions such as antibiotics and see the effectiveness, but look at the outcome of other processes based on alternative worldviews (such as religion, spirituality, etc) and you will see a mixture of good, bad, and inconclusive results (the efficacy of prayer would be a good example) which is generally a sign that there is no real effect.
There is a criticism of what I have just said however. That is that I am proposing using a scientific testing regime to test both science and other systems. Is that fair? Maybe not.
But now I get to the core question in this blog entry. That is: what is the alternative? If anyone disagrees with the scientific method then I would like to hear them propose something better. When I challenge someone this way I usually don’t get an answer at all and if I do get an answer it usually makes very little sense.
For example someone might suggest that faith is a good alternative. OK, let’s look at that idea. Faith is a belief in something without good supporting evidence. How do I decide which thing to believe? For example, if it is a religion then how do I decide which religion to have faith in? Many people will say it obviously has to be Christianity but that is just a consequence of being born in a country with where Christianity is the dominant religion. If I asked the same question in Saudi Arabia I would be told Islam is the obvious answer, or in India I might be encouraged to follow Hinduism.
This does not sound like a good way to establish a real, objective truth, because it depends so much on totally arbitrary starting parameters. Is the truth different depending on which religion is popular in the country you were born in?
Another possible solution is to look at the contents of the belief system in question and see if they fit the facts. But this isn’t faith any more, is it? In fact taking the ideas of a belief system and testing them sounds more like science! Unfortunately when you do this in every case the belief system is found to be severely lacking in which case it is necessary to revert to faith. So around and around the old circular logic roundabout we go!
If anyone believes in something based on faith we can almost immediately assume it is untrue because if faith is necessary to support something you can be fairly sure that it has failed all the real reality tests and faith is the only option left.
But what about revealed knowledge? The sort of thing found in holy books, like the BIble. Exactly the same criticism applies. Which holy book should we choose? And if we use real scientific investigation to test these books why do they always fail?
So let’s move beyond religious answers and look at other alternatives. What about philosophy? Well I have a lot of regard for philosophy but so much of it (not all) is somewhat pointless because it is untestable. If a number of philosophical theories are devised and there is no way to distinguish which is true then what is the point? I would suggest that the value of these theories is somewhat limited.
So now it all gets back to my second reason for supporting science: it gets results. Look back at the history of civilisation. Where has almost all of our real progress come from? Is it from religion, or philosophy or science (and its natural end result, technology)? I think if anyone was truly honest they would agree that science is the system which has produced the real results.
So there’s an open challenge to everyone. If you really think science has problems and is imperfect (it is) and you want to reject it based on that then tell me what is better. Whatever flaws science has I would claim it is much better than anything else we have. If you disagree let’s hear your better idea!
In my last blog entry I started talking about another one of my favourite things: the Hubble Space Telescope. Unfortunately that headed off track a bit and finished as a discussion of Edwin Hubble, the famous astronomer that the HST was named after. So I guess I should finish off the original subject now.
The idea of a space telescope goes back almost 100 years and the advantages of having an instrument above the Earth’s atmosphere have been obvious for a long time. Apart from avoiding the constant dread for every astronomer – cloud on the night of an important observation – having a scope above the atmosphere also gives better results than even a “perfect” observing night on Earth because even under excellent conditions the Earth’s atmosphere both blocks some wavelengths of light (such as infrared) and distorts the light which does get through.
There was further discussion on the idea until 1968 when NASA began developing plans for actually building and launching a space telescope. There were numerous delays, especially after the Challenger disaster, but eventually the HST was launched on Shuttle mission STS-31 on 24 April 1990. At the time the original cost estimate of $400 million had increased to $2.5 billion.
After the delays and cost increases it was extremely disappointing to find after the launch that the HST was severely flawed. Although the images it created were better than anything from Earth at the time they were still much less precise than expected.
The fault was in the main mirror which was the most precisely made optical element ever, being accurate to 10 nanometers. Unfortunately, even though the mirror was an incredibly precise shape it was the wrong shape because of an error in the testing done by the American optics company, Perkin-Elmer.
Building and fitting a new main mirror was impractical so it was decided to correct the error by fitting a new secondary mirror (much smaller than the main one) and by changing the optics in the instruments attached to the telescope. Perkin-Elmer also did this work and this time they got it right! The corrected telescope delivered stunningly precise images of space.
Here’s a few basic facts and figures about the HST: weight 11 tonnes, diameter 4.2 meters, length 13.2 meters, orbit height 569 kilometers (orbits the Earth once every 97 minutes at a speed of 28,000 kilometers per hour).
So an 11 tonne instrument is flying around the Earth at 28,000 kph. How is it pointed at different objects and, more importantly, how is it kept pointing at them? That is one of the more amazing abilities of the instrument. It can lock onto a target without deviating more than 0.007 arcseconds. That is the equivalent of the width of a human hair seen at a distance of 1 mile. That’s quite an impressive feat of engineering precision, I think!
The pointing is done using gyroscopes. As a gyro (a heavy spinning wheel) spins in one direction it forces the telescope which it is attached to to move in the opposite direction. This is very precise but quite slow technique but using rocket thrusters would be far less precise, consume fuel when used, and leave gas around the scope possibly spoiling the imaging. The gyros are powered from the HST’s solar panels and suffer none of these problems.
By 2010 the total running cost of the HST was about $10 billion, which sounds a lot. But that is for over 20 years of operation of a superb instrument which has made so many great discoveries. It also includes upgrades for many of the instruments attached to the HST.
Is that a lot? The US spent $4.7 trillion on bailing out financial institutions after the financial crisis. They wasted 470 times as much as the cost of the HST on helping out a bunch of worthless parasites. And in half the time the HST has been run (the last 10 years) the US has spent over 140 times as much ($1.4 trillion) on wars. And what do they mainly achieve apart from killing innocent people?
So the HST, even with significant cost overruns, has been great value for money. It truly deserves to be one of my favourite things.
This blog entry continues my series on my favourite things. I want to do another with a technology, space-based theme. Last time it was the Voyager spacecraft, this time it is the Hubble Space Telescope.
The HST is nearing the end of its life and it could so easily have been a total failure from the beginning, yet it has provided some of the greatest pictures ever of space, from relatively nearby planets in our Solar System to galaxies on the very edge of the observable Universe.
These pictures have not only been of great scientific value but they have been both beautiful and awe inspiring to many non-scientists. They have increased our knowledge of the Universe and increased the enthusiasm the public have for both astronomy in general and the increasingly beleaguered space program.
So let’s start at the beginning. The facility is called the “Hubble Space Telescope” so who or what is Hubble?
Edwin Hubble was a great American astronomer who mainly worked around the 1920s. He made several incredibly important discoveries: first, confirming that the Milky Way galaxy isn’t the whole Universe (yes, that knowledge is less than 100 years old); and second, discovering that the more distant a galaxy is the more quickly it is receding from our galaxy (the Hubble Law), in other words that the Universe is expanding (up until then it had been assumed that it was static).
He was a brilliant and dedicated observer rather than a theorist but in astronomy (and most other sciences) observation both leads and confirms theory and the two branches are equally important in increasing our understanding of the universe.
Some of Hubble’s work was best described as gruelling. At the time a lot of information was gathered by taking spectra of distant galaxies onto photographic plates. But the plates had limited sensitivity, the galaxies were very faint because of their distance, and the process of creating a spectrum made the light even fainter. So it was necessary to expose the plates for a long time to get a good image.
Because of the Earth’s rotation the stars move across the sky and the telescope’s drive (which moves the scope to track the stars) needed constant correction by the observer. So the astronomer had to sit in the cold looking through an eyepiece and correcting the tracking for long periods of time.
Hubble took some photos with exposures much longer than could be done in one night. He actually closed the shutter before sunrise and pointed the scope back at exactly the same place the next night and continued the same exposure on the same plate. In fact some exposures might have taken a week of all night guiding to get a single plate! It is an extraordinary example of skill and patience that he succeeded so well with these observations.
The big discoveries Hubble made settled some major questions at the time. There was a debate about whether our galaxy was the whole universe, because many people thought other galaxies were just smaller localised nebulae embedded in our galaxy. Hubble’s detailed observations showed the nebulae were really galaxies as big, and often bigger, than our own. So the size of the universe expanded by a factor of billions virtually over night.
His discovery of the expansion of the universe caused another even greater revolution. The spectrum for any bright object has a number of colours visible which show the elements it is made from (this explanation isn’t completely technically correct because I have simplified it here). Hubble found the pattern expected (because stars everywhere produce light through the same process) but in the wrong part of the spectrum. His conclusion was that the light was “red shifted” which is caused by an object moving away from the observer and “stretching” the colour of the light into the red.
He expected that he would find about the same number of galaxies red shifted (moving away from us) and blue shifted (moving towards us) but it soon turned out that almost every galaxy was moving away. Not only that, but the further away the galaxy was (determining distances in space is another complex and fascinating subject) the faster it was moving away.
The only logical conclusion is that the whole fabric of space is expanding. Note that any observer in any galaxy would see the same expansion pattern so this doesn’t mean that we are in a special place. The few close galaxies which are moving towards us are explained by the fact that galaxies also move around randomly but only with the closer ones, where the relative universe expansion is smaller, can the overall expansion be overcome by this smaller local motion.
And if the universe if getting bigger then in the past it must have been smaller, and go back far enough and it would have been zero size. So the potential for a beginning, which eventually lead to the Big Bang Theory, was then understood.
Even Albert Einstein had put a special factor into his equations for relativity to make the Universe static. Initially his work indicated it should be expanding but few people believed this at the time. So Einstein added the “cosmological constant” to balance gravity and make the universe static.
A few years later when Hubble showed that it was expanding Einstein admitted the constant had been “the biggest blunder of his career”. Ironically in the last few years it has become obvious that there is something very similar to the cosmological constant at work in the universe (so called “dark energy”) causing the rate of expansion to increase (it was previously thought it would decrease due to the effect of gravity) so maybe Einstein was right even when he thought he was wrong!
So you can see that the observations Hubble made really did revolutionise our understanding of the universe. Earlier in his life he was considering a career in law. What a waste that would have been!
I have just noticed that I have written a blog entry about Edwin Hubble, not the Hubble Space Telescope as I originally intended. It’s great the way one subject can lead to another, isn’t it? Since this entry is probably long enough already I will continue my thoughts on the HST in my next blog entry.
I recently listened to a podcast (you will probably not be surprised to hear) which made some interesting observations about the Fermi Paradox. While the podcast primarily deals with truth and is specifically against unsubstantiated beliefs I do need to say that the person being interviewed, David Brin, is most well known as a science fiction writer. But he is also a published scientist so while his ideas can be extremely speculative, you would also hope his speculations might have some basis in reality.
The Fermi Paradox is an idea I have discussed in previous blog entries but I will quickly describe it here again. Basically the paradox is that it seems that life should be very common in the universe and because of the great age of the universe that life should often become intelligent, yet we see no signs of intelligent life anywhere (except Earth presumably).
The universe is very big and it has become increasingly obvious that planets – and planets with roughly the right conditions for life – are very common. In the last few years the total number of known planets has increased from 9 (the planets of the solar system which included Pluto at the time) to over 1000 today (now only 8 in our solar system but many more orbiting other stars).
If we can find a thousand planets so quickly by looking at a tiny part of just one galaxy imagine how many there must be in the universe as a whole. If there are 10 planets orbiting each star and 100 billion stars in a galaxy and 100 billion galaxies in the visible universe there are a lot of planets out there (about 100 billion trillion according to my estimate based on these conservative numbers).
We have known for some time that the universe is very old: about 13.7 billion years by modern estimates. It is also known that the Sun and Earth, while still being very old, are much younger than the universe as a whole. The Earth is about 4.5 billion years old. So it follows there are potentially planets many billions of years older than ours which might have life billions of years more advanced.
I know it’s not that simple because first generation stars can’t form solid planets and life might require a whole series of fortunate accidents to get started, plus some of my numbers above are very rough guesses, but in general it seems reasonable to assume there should be billions of civilisations at least as advanced as ours out there.
So where are they?
Some people think intelligent aliens have visited Earth already which explains many UFO stories, but no UFO story has been positively proved to be an alien visitor and the phenomena described by people who have seen UFOs seems very unlike what we would expect from real extraterrestrials.
Maybe they might not be that obvious. Maybe we need to look systematically for alien intelligence. Well that has happened to a limited extent with various SETI projects which are mainly searching for radio signals with appear to have an artificial origin. So far there has been no result which can really be taken too seriously although there have been a few interesting findings, including the “Wow signal” which I might discuss in another blog entry.
So that’s the Fermi Paradox. What is Brin’s explanation for this apparent paradox?
He basically says that the assumption that life naturally proceeds to intelligent life then to a civilisation with advanced technology isn’t necessarily true.
He thinks civilisations on this planet have primarily followed a dominant pyramidal, oligarchic structure which represses progress in science, and is hyper-conservative. Currently most countries are democratic and encourage technological progress but that is the exception in the history of the world, not the rule. Look at how Rome and Greece ended after encouraging starts and how the Dark Ages held back the advances started in earlier times. It is rather depressing.
And look at the popularity of the crazy, superstitious, anti-scientific conservatism in the US today if you want a modern example. It’s certainly conceivable that the US could go the same was as those previous empires.
So Brin thinks a similar process might be common on other planets where intelligence gets started. Since similar biological and social evolutionary processes might happen everywhere the idea has some merit although it’s clearly highly speculative. The problem with the study of life in the Universe is that we only have one example (Earth) to draw conclusions from!
If advanced technology is rare then it makes our responsibility to pursue it even greater. Brin thinks it might be humans responsibility to rescue the rest of the universe from anti-progressive, ultra-conservatism! Yes, I know this is really drawing massive conclusions from almost no evidence, but it is an interesting idea.
I’m not sure if he’s ever written a science fiction novel based on this theme because I haven’t ready many of his books. But he has such an interesting way of thinking about this subject that I think I might put some of his books on my reading list!
Today I want to start a series discussing some of my favourite things. There are few things which I just think are astoundingly good, and these can be placed in several categories, but for this edition of my favourite things I am going to talk about one of my favourite achievements of human technology.
Specifically I want to discuss the two Voyager spacecraft. These were launched in 1977 and have been travelling and transmitting data back for the 35 years following. It is expected they might still have enough power to run some instruments up to the year 2030. That’s over 50 years of service in space – quite an achievement in any circumstances and even more astonishing when you consider the relatively primitive technology available when they were built and the fact they were originally designed for a 5 year mission.
The Voyagers’ primary mission was to explore Jupiter and Saturn, and Voyager 2 went on to visit Uranus and Neptune as well. It took several years to travel from one planet to the next. After leaving Earth in 1977 Voyager 2 arrived at Jupiter in 1979, Saturn in 1981, Uranus in 1985 and Neptune in 1989. The spacecraft discovered rings, new moons, and many other phenomena such as lightning and wind turbulence in the planets. The image quality of images was considerably better than anything else up until then. Try a Google image search for “Voyager images Jupiter” (or Saturn, Uranus, Neptune depending on your favourite planet) to see some examples.
Voyager 1 has now travelled over 18 billion kilometers and Voyager 2 has travelled 15 billion (they took different routes and travelled at different speeds to explore different planets). That puts Voyager 1 beyond the edge of the Solar System at a distance 123 times greater from the Sun than the Earth. It takes radio signals (travelling at the speed of light) almost a day to reach the Earth from this distance.
In about 300,000 years Voyager 2 is expected to approach the bright star Sirius but long before that much faster moving spacecraft will have overtaken it in distance travelled. It does illustrate the scale of the universe though, when you consider that it takes hundreds of thousands of years to travel to even the closest stars.
The team at NASA have done amazing things to keep the spacecraft working. Various systems have been shutdown to preserve power, but the nuclear power source (the three plutonium powered generators which generate almost 500 watts of power in total) are still working after all that time.
Last year (I haven’t found an update for 2012) the data upload rate was 16 bits per second. That is the speed data can be sent to the spacecraft. At that rate this blog entry would take over half an hour to send. Data can be sent from the spacecraft to Earth at a somewhat more respectable 160 bits per second!
That may seem slow but although the radios in the Voyagers are about 8 times stronger than what is in your cell phone they are expected to send data about 3 billion times further, so it’s not surprising that the data rate has to be kept fairly low. In fact the power reaching Earth from the Voyagers is about one ten million billionth of a watt (0.0000000000000001 W). I have estimated that you would need to gather energy from this signal for hundreds of years to collect enough to be equivalent to a single drop of rain falling!
You might think that a mission like this would be expensive. That depends on your definition of the word expensive but both spacecraft have been designed, launched and operated for under a billion dollars. That’s about 8 cents per person (living in the US) per year. It’s also 1,500 times less than the cost of the wars in Iraq and Afghanistan. Anyone who says the space program is too expensive just doesn’t have a clue what they’re talking about!
So I think those little spacecraft (actually they are fairly big and weigh almost a tonne each but I still think of them as small and cute) which are still out there operating on the edge of interstellar space really are a magnificent example of what human science and engineering can achieve, and something which all humans should be proud of.
We need more of this sort of thing and I find it really frustrating when science and engineering budgets (such as NASA’s) are cut while thousands of times more is spent on wars and bank bail-outs. After 50 years the Voyagers are something special but In 50 years those wars will just be an unfortunate incident in history and who would possibly care about something as meaningless as a bank?
Well it’s Carl Sagan Day again so it must be time to comment on this most inspiring science communicator again. If you want a brief background on Sagan check my blog entry of 2010-11-09 “Carl Sagan Day” for a quick introduction. In this entry I thought I would discuss some of Sagan’s ideas by using some of his most well known quotes.
Quotes about the universe…
Quote 1: “Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people.”
In this quote Sagan describes a phenomenon which has been steadily overtaking our old ideas of where we stand in the universe. First, the Earth was the most important thing and we were the most important part of God’s creation. Then we had to accept that the Sun was at the center of the Solar System, not the Earth, then we had to accept that humans were just another product of evolution like every other species. Just a hundred years ago we discovered the true scale of the universe and that our entire galaxy is just one of hundreds of billions of others. In the last few years we have discovered many planets orbiting other stars. There are probably a trillion in our galaxy alone and surely some of those must have life. And the future? Well I think the next thing will be that our universe is just one of a possibly infinite number. Sort of puts things in perspective, doesn’t it?
Quote 2: “The universe is not required to be in perfect harmony with human ambition.”
This quote is related to the previous one. Not only are we a tiny part of the whole universe but the universe isn’t even particularly well suited to our requirements. Only a tiny part is suitable for life, the scale of the universe makes it impossible for us to really experience it, and various disasters could eliminate our society at any time. But there is hope…
Quote 3: “The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars.”
Of course it is inevitable that some sort of interstellar travel will become possible eventually as long as out civilisation isn’t ended before that can happen. Potential causes of the end could be through an environmental disaster, a disaster from space such as an asteroid collision, or through a global war. Travel to other stars won’t be easy because space is big, but there are several ways this problem could be overcome, none of which I have space to elaborate on here!
Quote 4: “In the vastness of the Cosmos there must be other civilizations far older and more advanced than ours.”
Yes, this is the view of most sensible people who think about the issue. The puzzling thing is why is it not obvious that these civilisations exist. Even in a thousand years (which is a tiny fraction of the age of the universe) we will be capable of technology which changes out planet, star, (refer fo Dyson spheres for example) and maybe even local galaxy substantially. What about technology millions or billions of years more advanced? Either life really, really rarely advances to that advanced stage or when it does it is so advanced we don’t even know how to recognise it. Again, this is a fascinating topic in itself, but again I don’t have space to elaborate!
Quotes about science…
Quote 5: “Science is a way of thinking much more than it is a body of knowledge.”
This is something many critics of science don’t understand. Even in the rare cases where science is wrong or inaccurate that isn’t really significant. Science is about how to discover information, not so much what that information is. Briefly, here’s the process: learn as much as you can about the subject, find an open question, create a hypothesis about the question, test it, formulate a theory, test the theory, modify it or toss it out if necessary, repeat.
Quote 6: “I can find in my undergraduate classes, bright students who do not know that the stars rise and set at night, or even that the Sun is a star.”
Yes, it’s rather depressing that people (even intelligent people) are so ignorant. But maybe it doesn’t matter because everyone is ignorant abut something. Scientists might be ignorant about pop culture, or embroidery, or the history of Inner Mongolia, does that make them generally ignorant? Actually I don’t mind people being ignorant about science as long as they accept it. If you’re ignorant then you don’t get an opinion on evolution, or global warming, or genetic modification, or nuclear energy, or stem cells. OK?
Quote 7: “Imagination will often carry us to worlds that never were. But without it we go nowhere.”
Basically he’s saying that we need to explore new ideas but we have to be careful not to give all new ideas equal status. A new idea from a physicist about quantum theory is worth something but a new idea about how to create a perpetual motion machine by a retired gardener probably isn’t.
Quotes about skepticism…
Quote 8: “Skeptical scrutiny is the means, in both science and religion, by which deep thoughts can be winnowed from deep nonsense.”
Skeptical scrutiny can be applied in the areas of science and religion, but I never see it actually happening in religion which is why religions are so full of myths and obsolete ideas. I’m not sure what Sagan’s point was in this quote because surely he knew this.
Quote 9: “A celibate clergy is an especially good idea, because it tends to suppress any hereditary propensity toward fanaticism.”
This is may be slightly unfair because only a minority of members of the clergy are fanatics. Plus religion has other ways of ensuring its ideas persist so whether the clergy are celibate or not is basically irrelevant. Maybe this was meant to be mainly a throw away line disrespecting religion more than anything deeper.
Quote 10: “What I’m saying is, if God wanted to send us a message, and ancient writings were the only way he could think of doing it, he could have done a better job.”
This is a good point. Many people claim their holy books, such as the Bible, are perfectly clear. Others say they require careful interpretation. Generally what I find is they are clear until it can be shown that they are wrong then that part is suddenly open to more interpretation. It’s quite a dishonest approach really, but Sagan obviously saw through it. If God has got an important message for us he sure has an odd way to of communicating it.
Quote 11: “The fossil record implies trial and error, an inability to anticipate the future, features inconsistent with an efficient Great Designer.”
Of course. Nobody who understands the fossil record (and the molecular evidence and the evidence from extant species) could ever consider creationism or intelligent design as viable theories. Even if there was a designer, he wasn’t very intelligent!
And now a quote I think is quite misleading…
Quote 12: “An atheist has to know a lot more than I know. An atheist is someone who knows there is no god. By some definitions atheism is very stupid.”
The key thing here is the phrase “by some definitions”. Sure if someone says there is no god of any type and they know that with absolute certainty then they probably are stupid. But no atheist I know says that. What they do say is either: we know beyond any reasonable doubt that a particular god (for example the one described in the Bible) can’t exist; or there is no good evidence suggesting any sort of god (using the common definition of the word) exists so we currently reject the idea. That’s what atheism really is and I think that is beyond fair criticism.
So that’s a few highlights from Sagan’s various roles as scientist, communicator, and skeptic. I’ll finish with my favourite Sagan quote ever (and one that has already appeared a few times in this blog): “Somewhere, something incredible is waiting to be known.”
The great physicist, Niels Bohr, once commented that he was unsure about a new quantum theory idea by using the following phrase: “Your theory is crazy but is it crazy enough to be true?”. In fact, the exact quote was “We are all agreed that your theory is crazy. The question that divides us is whether it is crazy enough to have a chance of being correct”, but I don’t think that’s quite as snappy!
Anyway, there is no doubt that many theories at the frontiers of modern physics, especially in quantum theory and relativity, are so crazy that it must be difficult for many people to take them seriously. The idea that a photon is both a particle and a wave, that two particles separated by a great distance are entangled, that a system can be in two states simultaneously until that state is observed, that a clock will run more slowly as its speed increases, that two objects approaching each other at a particular speed don’t actually pass each other at double that speed, etc. It’s all crazy yet according to careful observation it’s also true!
Not only is it crazy but, as your knowledge of physics becomes greater, it becomes more crazy! A totally naive person might not notice the craziness immediately but as their knowledge of classical systems increases they will see how quantum and relativistic physics is mad! But also when you reach a particular level of knowledge all of this suddenly starts making a sort of odd sense!
So that is my introduction to crazy physics. The idea I want to explore in detail here is really crazy: it’s the idea that our whole universe might just be a simulation in a computer! Yeah, I know, that really is crazy. But as Bohr would ask: is it crazy enough to be true?
Before I go any further I do have to say that craziness is not a guarantee that something is true. Obviously in many cases the opposite is true. There are different types of craziness and some are just simply disconnected from reality. It’s similar to the situation when someone invents a new perpetual motion machine and is ridiculed by real engineers and scientists. They often say something like “well they laughed at [insert well known scientist here] too, and he was proved right!” Yes, being laughed at is not sufficient in itself. I agree that some people laughed at the Wright Brothers, but they also laughed at Bozo the Clown!
Back to the “universe in a computer” idea. A research team recently simulated a small part of the universe in a computer. I don’t mean they made an imitation of it, as far as we can tell they genuinely exactly recreated it. OK, I have to admit this was a very small part of the universe, in fact it was an area a few femtometers across (a femtometer is one thousandth of a trillionth of a meter). But it shows that this type of simulation isn’t impossible.
Now some philosophers have come up with the following argument: at least one of the following is true: the human species will probably become extinct before reaching an advanced “posthuman” stage, or a posthuman civilisation will not run simulations of their past, or we almost certainly live in a simulation. The justification for the third statement goes something like this: if statement one is false and humans survive to become far more advanced then other civilisations must have done that already, if statement 2 is false and advanced civilisations do run simulations then there must be many of those simulations running now. If there is only one real universe but many simulations then the greatest chance is that ours is one of the simulations.
So in summary: either humanity will die out soon, or we won’t create advanced simulations of the universe, or we almost certainly live in a simulated universe.
The argument all seems to make sense but it does make some assumptions. First, that there are many advanced civilisations in the universe. Given how big the universe is and how late humans evolved (almost 10 billion years after the Big Bang) then that isn’t unreasonable. Second, that advanced civilisations will be able to and will want to create simulated universes. With the rate of progress in information management over the last 50 years it seems almost inevitable that after a few thousand or even million years of similar progress that such a simulation would be created. Third, that there is only one “real” universe. Actually that doesn’t matter because the ratio of simulated to real universes is likely to be high irrespective of the number of real universes.
But I can’t help feeling the same way about this argument as I do about many other philosophical discourses. It seems more like sophistry than a genuine argument. It’s not quite as blatantly bad as the ontological proof of god (for example) but it still seems pretty bad. What we really need is some empiricism to sort the truth from the supposition. But that’s not possible. Or is it…
Some scientists think that it should be possible to tell if we do live in a simulation. A simulation could not have infinite resolution – there would have to be a limit just like there is with simulations we can run today. We should be able to detect these “pixels” in the universe. They have proposed an effect which should be visible in the path of cosmic rays.
I also think it’s interesting that our universe does indeed seem to have a more basic “resolution”. The Planck length could be a resolution in space and the Planck time could be the resolution in time. Both of those numbers are ridiculously small. The Planck distance is about 1 billion trillion trillionth of a millimeter and the Planck time is about 5 billion trillion trillion trillionths of a second. So if this universe is a simulation it must be an extremely detailed one!
So the simulated universe theory is an interesting one and it’s also a crazy one. But is it crazy enough to be true? Or is it just too crazy…
I listen to quite a lot of scientific podcasts and other material in the average week. I subscribe to podcasts from Nature, Guardian Science, and other fairly respectable sources. I often hear about trends and new research before they are well known to the general public and I have a fairly good idea of where the trends and consensuses are on various topics.
So it never ceases to amaze me when I hear what the average person with no interest in science actually thinks, especially on topics of a controversial nature. It’s like a totally different world when I compare what I have heard from the world’s leading researchers with what other people think is happening and who rely on totally different sources.
For example, I often see climate change deniers quoting phrases like “global warming theory is in serious doubt after new research” or “climate change alarmists were wrong” or “there has been no warming in last 10 years”. In many interviews with the world’s leading experts I never hear anything which could be remotely construed this way. As time goes by climate change becomes more certain, the evidence more incontrovertible, and the models more accurate. Where does this opposing view come from? Apparently they just make it up!
A similar thing happens in other fields where there is an opposing view such as evolution (of course I mean an opposing view from people who are ignorant of the subject or with a political or religious bias, not real researchers). I recently engaged in a debate with a creationist over whether new data from the ENCODE project (a public research consortium, the Encyclopedia Of DNA Elements) disproves evolution. This person was not a nut, but he just totally cherry picked the evidence and warped it into his own world-view. He also refused to discuss the real issues and simply repeated his own warped opinions over and over.
When I hear biologists discuss evolution (even those involved with ENCODE) there isn’t the slightest hint that they think evolution theory is wrong, if anything their findings support evolution even more, but the subject isn’t even usually discussed because to the experts it just isn’t an issue any more: evolution is a fact.
But the public view is often quite different. Polls in the US indicate that only about half of the population there believe evolution, and a recent poll here in New Zealand showed less than half think that global warming is real and caused by humans. The global warming poll was a casual one run in the Herald newspaper, so it wasn’t scientifically accurate, but I think it gave a fair indication of the public view.
Here’s the result. The question was: “What’s your take on climate change?” (not a very precise question to be begin with, but let’s move on). “It’s a real problem and humans are the cause” got 49% support, “It’s a real problem but humans aren’t the cause” got 19% and “It’s a load of old cobblers” got 32%. So less than half gave the answer which is well supported by the science and a third disputed the reality of the phenomenon completely!
There is definitely controversy around climate change but it only takes two forms: first, there are people who for reasons of their religion, politics or ignorance reject it; and second there is a valid debate on the correct response to the problem. Actually, I should concede here that there is a third group: those who genuinely dispute the science and have some degree of expertise in the area, however this group is extremely small and often a hidden agenda is involved.
So there is no real scientific controversy here, just like there is none relating to evolution. The controversy is an artificial political one: it is scientific fact against political opinion. Note that I am talking about the basic idea of whether anthropogenic global warming is real, not what our response should be – I think there is still real debate around that and that is a real question with a significant political component (unlike the reality of the phenomenon which is – or should be – entirely scientific).
But this is a common problem in today’s world: subjects which belong in one domain are debated in another and this leads to total irrationality. For example, the scientific issue of evolution is real so instead of debating that fact religious people should get on to discussing how that affects their beliefs. Another example: global warming is a scientific reality so the next step is to discuss the political response to that reality. It is not for religion to dispute the science of evolution or for politics to do the same to global warming. At least it isn’t if we want a rational outcome.
But that does bring out a factor which I haven’t mentioned yet: many people don’t trust science. It’s odd because those same individuals use the products of science, like the internet, as a medium for saying why they distrust it. Or they make use of the advantages we have gained from science, such as modern medicine, to extend their lives while debating evolution which is the most important theory underlying biology: the science medicine is based on.
It’s bizarre. It would be like me creating a brilliant argument against the existence of God and then distributing it on church noticeboards (and that would be after I survived a nasty disease by praying for a cure). Still, people are often very poor at recognising the irony inherent in their positions. That’s one of the most amusing things about engaging them in debate!
After a few more negative, cynical, and controversial blog entries it’s time to get back to the “little questions” again, the ones I started discussion about a month ago.
I’ve already dealt with “Why is the Moon round?”, “Why is the sky blue during the day?”, and “Why is the sky dark at night?” so what’s next? How about “what is a star?”
I did a “pop quiz” and found that most people know roughly what a star is, something like “a big burning ball of gas”.
That’s not quite true: stars are neither gas, nor burning. Stars are made from plasma, not gas, but gas is a fair approximation. Also they aren’t burning, they are undergoing nuclear fusion which is a far more efficient process. If a star was burning a conventional fuel (like coal for example) it could burn for about 6000 years, but nuclear fusion allows a star to shine for billions of years.
Interestingly there was some confusion abut the difference between the Sun and a star. People seemed to realise the two things were similar but some thought the Sun was brighter and hotter because it is bigger.
Of course the reality is that the Sun is a star. There is absolutely no difference between a star and the Sun. The Sun seems brighter simply because it’s much closer. The Sun is just 150 million kilometers away but the stars visible without a telescope are between 40 trillion and 100 million trillion kilometers away. There are stars much further away than that but a large telescope is needed to see them.
How do we know? Stars are so far away that they can usually only be seen as single points of light so couldn’t they be something totally different from our Sun? Almost 200 years ago the great philosopher, Auguste Comte, said that humans will never be able to visit the stars, that we will never know what stars are made out of, that that’s the one thing that science will never understand. He was right that visting the stars isn’t likely in the foreseeable future, but it was only a few years later that science discovered what stars are made of thanks to spectroscopy. And it turns out that stars are made of similar things to the Sun.
And how do we know the distance to the stars? That turns out to be an extremely difficult problem. The most direct measure, which works for close stars, is to use parallax. When a star is observed from one side of the Earth’s orbit, then from the other side 6 months later the observer on the Earth has moved 300 million kilometers compared to the Sun. That causes the star to seem to move against distant objects like dimmer stars and galaxies. But how much does it move? Not much. Imagine a small coin at a distance of 5 kilometers. That is how much the a close star seems to move, and the more distant the star the less the apparent movement. But the measurement has been done and the distances are known. Looking at the apparent brightness and size of a star and knowing its distance allows an estimate of its real size and brightness.
The Sun is not even a particularly big or bright star. It’s quite average and almost all the stars visible in the sky at night are much brighter. For example, the star Rigel in Orion is over 100,000 times brighter than the Sun, and another star in that constellation, Betelgeuse, is a billion times the Sun’s volume.
I think the facts above are quite significant. They mean that the Sun – the most significant thing to us (apart from the Earth itself maybe) – is just one of many other objects and isn’t really special in any way. How many stars (or Suns) are there in the universe? About the same number as there are grains of sand on our planet!
That’s an extraordinary thing really. Imagine going to a beach and picking up a handful of sand and counting the grains of sand. Now think about how many grains are on the beach and how many there are on all the beaches on the whole planet. There are a similar number of stars in the universe (the exact number is debated a bit but it’s about 300 trillion trillion) and each of those is like our Sun (which is well over a million times the volume of the Earth) and probably has orbiting planets like the Earth.
Yes, we think that planets might be quite common. Because of the distance to stars which might have planets orbiting them (apart from the Sun) is so great it’s difficult to observe anything except the star, but recently telescope technology has progressed sufficiently (the Kepler space mission and various big ground-based telescopes) to allow planets to be detected. And plenty have been found, including some much bigger than any of the planets in our Solar System, and others very similar to the panets we already know.
And just to complete the whole story about the insignificance of anything in relation to the universe as a whole, we don’t even know the size of the universe and according to some ideas it might be infinitely big. The universe we see, including its apparent beginning in the Big Bang, could be just a localised part of a much bigger (possibly infinitely big) multiverse. Then there really would be an infinite number of stars not just a few trillion trillion like we can see in the visible part of the universe.
Start with the question “what is a star” and finish with almost philosophical musings regarding the universe on the grandest of scales. Another little question – another big answer!
I think it’s time to tackle some more of the little questions I discussed a few days back. In the earlier entry I pointed out how the question “why is the Moon round?” can lead to some deeper understanding of how the universe works, so what about another similar type of question. Hey, let’s do a two for one deal here. I’ll tackle the two related questions: “Why is the sky blue during the day?” and “Why is the sky dark at night?”
There’s a simple explanation of why the sky is blue and it’s one you don’t hear very often. The explanation is this: the sky is blue because that’s the colour of air. If the sky was made of chlorine instead of nitrogen and oxygen it would be green because that’s what colour chlorine is.
So the question of why the sky is blue is exactly the same question as why a rose is red or coal is black. There is one complicating factor though: it takes a lot of air to see the colour because the air isn’t very dense. When you look through small amounts of air, such as across a room you don’t see the colour because there just isn’t enough air there.
But saying the sky is blue because it’s made of blue stuff is only the first step. What is it which makes anything a particular colour? It’s because of the way the atoms or molecules the object is composed of interact with the light which reach them. If they absorb certain colours then the colours which remain will continue to the observer’s eye or the camera or whatever is looking at the light. The Sun produces light of many colours but only the blue survives the journey through the air so that’s the colour we see.
We might need to take the explanation one step further though. Why do certain particles absorb light of some colours but not others? It’s because of the energy of the atom’s electrons (amongst other reasons). If the energy of the electron corresponds to that of the light they will interact.
Finally we have to ask why electrons have a certain energy and why is it always the same for the same atom? That’s because of quantum mechanics. Electrons can only “orbit” the atom at certain “distances” because that’s all that quantum theory allows.
So a blue sky (or in fact any colour of anything) tells us a lot about the nature of the the material producing the colour. In fact there is a whole branch of science which uses light to analyse what objects are made of. Astronomers have used spectroscopy to analyse the light from the Sun (and other bodies) for years and by analysing the light in minute detail they can tell a lot about the material in the Sun, not only what’s there but a lot about magnetic fields, temperature, and pressure as well.
In fact in the early days of the spectroscopic analysis of the Sun astronomers found some strange colours (or actually dark lines in the continuous colour for reasons which I won’t go in to here) which could only belong to a new element. That element was helium and it was found in the Sun (hence its name) before it was found in a laboratory on Earth.
Now we know why the sky is blue during the day what about the second question: why is it dark at night?
Obviously it’s dark because there is no light to give it a colour. Black is the absence of light so obviously the night sky should be dark. Or should it?
These are the early assumptions about the nature of the Universe held by most astronomers: the universe is roughly the same everywhere, it is infinite in time, it is infinite in space, and it isn’t expanding or contracting.
If you know anything about cosmology you will know these assumptions haven’t held up well to modern observations but at the time (up to about 100 years ago) they seemed to make a lot of sense. The problem was that if the universe was infinite and the same everywhere there would be an infinite number of stars which should produce an infinite amount of light. So the whole sky should be as bright as day! At that time the fact that the sky was dark was known as “Olbers’ Paradox” and it took a while to resolve it.
There were objections to this idea but they didn’t stand up to scrutiny. For example, you might think that the stars further away would be dimmer so they would contribute less light. But the further away you look the bigger the sphere you are looking at so there would be more stars in that area. The number of stars at any distance would vary with the square of the distance and the brightness would vary with the inverse square. They would cancel each other out making the distance irrelevant.
Another objection might be that dark dust and gas (which there is plenty of in the universe) would block the light. But after blocking this light that dust would get hotter until eventually it re-radiated the light hitting it and would have no effect on the total light.
The only explanation was that one or more of the assumptions were wrong. We still think the universe is roughly the same everywhere so that one is OK. After the Big Bang was discovered it seemed to make sense that the universe wasn’t infinite (in time or space) but even that cannot be assumed to be true according to some ideas. The critical thing was the fact discovered in the early 1900s that the universe is expanding.
There are actually many stars beyond a distance where the universe is expanding away from us at faster that the speed of light. Because the light from those stars only travels at the speed of light it cannot reach us. You might know that nothing can travel faster than light which seems to make this idea illogical. Actually no matter or energy can, but the fabric of the universe can expand at any speed, so relativity is not “broken” by this fact.
So you can see that the colour of the sky is actually a deeply significant observation. The blue sky during the day tells us something about physics at the smallest scale as described by quantum theory and the dark sky at night tells us something about the universe at the largest scale as described by cosmology and relativity.
If you look hard enough the simplest thing can be the most meaningful.