Posts Tagged ‘cosmology’

Do It Yourself

March 3, 2017 Leave a comment

I was going to post this comment as part of an anti-creationist rant but I realised that there was so much to it that I really needed to post it as a separate item. The issue I wanted to tackle was how many believers in mysticism base their beliefs on revealed sources, such as holy books, but the same criticism could be made against “rational” people, like myself, because I also use sources (such as science books, Wikipedia, etc).

So basically what I wanted to do was to show that anyone can discover significant things about the real world by themselves without relying on any information from existing sources, and that they can show anyone how to do the same observation/experiment which would prove their point beyond any reasonable doubt.

I decided to choose the age of the universe as a suitable subject, because it was a controversial subject (there are many young Earth creationists), and it was relatively easy to test. Of course, as I intimated above, it got more complex than I imagined. However, here is my proof – which anyone with a bit of time and a small budget can follow – that the universe, and therefore the Earth, is much older than the 6000 years the young Earth creationists claim.

I could start by trying to establish the age of the oldest things I know of. I could use biology, archaeology, chemistry or physics here, but I know a bit more about astronomy, so let’s use that.

We know the light from stars travels through space at the speed of light. If the stars are far enough away that the light took more than 6000 years to get here then the universe must be more than 6000 years old, so creationism is wrong. I know there are some possible objections to these initial assumptions but let’s leave those aside for now.

First, how fast is the speed of light? Can I figure this out for myself or do I need to take it on trust (some would say faith) from a book? Well it is actually quite easy to figure this out because we can use a highly regular event at a known distance to calculate the time it took for light to reach us. The most obvious choice is timings of Jupiter’s moons.

The moons of Jupiter (there are 4 big ones) take precise times to complete an orbit. I can figure that time out by just watching Jupiter for a few weeks. But we would expect a delay in the times because the light from an event (like a Moon going in front of or behind Jupiter) will take a while to reach us.

Conveniently, the distance from the Earth to Jupiter varies because some times the Earth and Jupiter are on the same side of the Sun, and others the opposite side. So when they are on the same side the distance from the Earth is the radius of Jupiter’s orbit minus the radius of the Earth’s, and when they are on opposite sides it is the radius of Jupiter’s orbit PLUS the radius of the Earth’s. Note that the size of Jupiters orbit doesn’t matter because the difference is just double the size of the Earth’s (in fact it is double the radius, or the diameter).

So now we need to know the size of the Earth’s orbit. How would we do that? There is a technique called parallax which requires no previous assumptions, it is just simple geometry. If you observe the position of an object from two locations the angle to the object will vary.

It’s simple to demonstrate… Hold your finger up in from of your eyes and look at it through one eye and then the other. The apparent position against a distant background wall will change. Move your finger closer and the change will be bigger. If you measure that change you can calculate the distance to your finger with some simple maths.

In astronomy we can do the same thing, except for distant objects the change is small… really small. And we also need two observing locations a large distance apart (the further apart they are, the bigger the change is and therefore the easier it is to measure). Either side of the Earth is OK for close objects, like the Moon (a mere 384000 kilometers away) but for stars (the closest is 42 trillion kilometers away) we need something more. Usually astronomers use the Earth on either side of its orbit (a distance of 300 million kilometers) so the two observations will be 6 months apart.

So getting back to our experiment. You might think we could measure the distance to a star, or a planet like Jupiter, or the Sun using this technique but it’s not quite so simple because the effect is so small. What we do instead is measure the distance to the Moon (which is close) using parallax from two widely separated parts on the Earth. I admit this needs a collaborator on the other side of the Earth, so it involves more than just one individual person, but the principle is the same.

Once we know that it can be used to measure other distances. For example, if we measure the angle between the Moon and Sun when the Earth-Moon-Sun angle is a right angle we can use trigonometry to get the distance to the Sun. It’s not easy because the angle is very close to 90 degrees (the Earth-Sun side of the triangle is much longer than the Earth-Moon side) but it can be done.

So now we know the difference in distance between the Earth and Jupiter in the two situations I mentioned at the start of this post. If we carefully measure the difference in time between the timings of Jupiter’s Moons from Earth when Earth is on either side of its orbit we get a difference of about 16 minutes. So light is taking half of that time to travel from the Sun to the Earth. We know that distance from the previous geometric calculations, so we know the speed of light.

Note that none of this is open to any reasonable criticism. It is simple, makes no assumptions which can fairly be questioned, and anyone can do it without relying on existing knowledge. Note that if you want to derive the basic trig calculations that is fairly easy too, but few people would argue about those.

So the Sun is 8 light minutes away meaning the light we see from the Sun left it 8 minutes ago. We are seeing the Sun literally as it was 8 minutes in the past. This means it must have existed 8 minutes in the past. But who cares? Well this is interesting but looking at more distant objects – those not just light minutes away but light years, thousands of light years, millions of light years away say more about the true age of the Universe.

So we can use this idea in reverse. Above we calculated a distance based on a time difference and the speed of light. Now we will calculate a time based on distance and the speed of light. If a star is 10,000 light years away the light left it 10,000 years ago, so it existed 10,000 years ago, so the universe is at least 10,000 years old.

There is only one direct method to calculate distance and that is parallax. But even from opposite sides of the Earth’s orbit – a baseline of 300 million kilometers – parallax angles are ridiculously small. But with a moderate size telescope (one which many amateurs could afford), and careful observation, they can be measured. The parallax angle of the closest star is about 800 milliarcseconds, or 0.01 degrees. That gives an angle which is the equivalent of the width of a small coin about 5 kilometers away.

Do this observation, then a simple calculation, and the nearest star turns out to be 40 trillion kilometers (4 light years) away. When we see that star we see it as it was 4 years ago. In that time the star could have gone out or been swallowed by a black hole (very unlikely) and we wouldn’t know.

The greatest distance so far detected using parallax is 10,000 light years, but that was with the Hubble Space Telescope, so that is beyond the direct experience of the average person! However note that using this direct, uncontroversial technique, the universe is already at least 10,000 years old, making young Earth creationism impossible.

Another rather obvious consequence of these distance measures is that stars are like our Sun. So if we know how bright stars are we can compare that with how bright they appear to be and get a distance approximation. If a star looks really dim it must be at a great distance. The problem is, of course, that stars vary greatly in brightness and we can’t assume they are all the same brightness as the Sun.

There is another feature of stars which even an amateur can make use of though – that is the spectrum. Examining the spectrum can show what type of star produced the light. The amateur observer can even calibrate his measurements using common chemicals in a lab. The chemicals in the star are the same and give the same signatures (approximately, at least).

So knowing the type of star gives an approximation of the brightness and that can be used to get the distance. The most distant star visible to the naked eye is 16,000 light years away. This would be bright enough to get a spectrum in a telescope, determine the type of star, and estimate the distance. Of course, it would be hit and miss trying to find a distant star to study (because we’re not supposed to use any information already published) but enough persistence would pay off eventually.

There are objects in the sky called globular clusters. These are collections of a few hundred thousand to a few million stars, quite close together. To the naked eye they look like a fuzzy patch but through a small telescope they can be seen to be made of individual stars. A simple calculation based on their apparent brightness shows they are tens of thousands of light years away. A similar technique can be applied to galaxies but these give distances of millions of light years.

In addition, an amateur with a fairly advanced telescope and the latest digital photography equipment – all of which is available at a price many people could afford – could do the investigation of red-shifts originally done by Edwin Hubble over 100 years ago.

A red shift is the shift in the spectrum of an object caused by its movement away from us. As I said above, the spectra of common chemicals can be tested in the lab and compared with the spectrum seen from astronomical objects. As objects get more distant they are found to be moving away more quickly and have higher red shifts. So looking at a red shift gives an approximate measure of distance.

This technique can only be used for really distant objects, like galaxies, so it is a bit more challenging for an amateur, but it will give results of millions to billions of light years, meaning the objects are at least millions or billions of years old.

There are some possible objections to everything I have discussed above. First, maybe the speed of light was much faster in the past meaning that the light could have travelled the vast distances in less time than assumed, meaning the universe could still be just 6000 years old.

Second, the light from the objects could have been created in transit. So a galaxy could have been created 2 million years ago but its light could also be created already travelled 99% of the way to the Earth.

Finally, maybe there is a supernatural explanation that cannot be explained through science or logic, or maybe all of the evidence above is just the malicious work of the devil trying to lead us all astray.

The second and third objections aren’t generally supported, even by most creationists, because they imply that nothing we see can be trusted, and God is not usually thought to be deliberately misleading.

The first one isn’t totally ridiculous though, and there is some serious science suggesting the speed of light might have been faster in the past. But do the calculations and that speed would have to be ridiculously fast – millions of times faster than it is now. If it was changing at that rate then we would see changes over recorded history. So that claim could also be checked by anyone who was prepared to dig into old sources for timings of eclipses, the length of the day, etc.

Astronomy is an interesting science because so much of it is still do-able by amateurs. Follow the steps above and not only will you get a perspective on some of the greatest work done in the past, but you will also make for yourself a truly fundamental discovery about the universe: that it is really old.

It requires no faith in authority, no reference to trusted texts, and no unfounded assumptions. It just involves a few years of dedicated observation and study. I admit I haven’t done all of this myself, but it’s good to know I could if I wanted to.

The Fermi Paradox Again

February 23, 2017 Leave a comment

NASA recently announced the discovery of 7 Earth-like planets orbiting the relatively close star, Trappist-1, and that 3 are in the “Goldilocks Zone” (not too hot, not too cold). It is now expected (at least I have heard this although I don’t think it is officially stated anywhere) that almost all stars have planets and that a significant fraction of them might have conditions similar to Earth.

This is significant because for many years no one knew how many planets existed in the universe (although there were some discoveries going back to 1988 it was only Kepler, HARPS, and some other new advanced telescopes more recently that lead to significant numbers of discoveries). So it was generally assumed that planets were common but there was no way of knowing.

Another great mystery of the universe is how likely is life to arise and under what conditions. Here we are even worse off than with the planets because we are literally working with a sample size of 1. No other life has been discovered outside of the Earth, although there have been some interesting discoveries on Mars, none have lead to any proof of even primitive life.

It is generally assumed that life will have to be broadly similar to what we have here on Earth. I don’t mean similar in any superficial sense but in broad principles. So it will be based on carbon, because carbon is the only element in the universe which bonds to other atoms (and itself) with sufficient complexity to form molecules suitable to base life on. We also know that the elements we know about are the only ones which can exist in the universe.

The chemistry of life also requires a solvent, and water is the obvious choice. So these chemical requirements limit the temperature and other factors that life would need, which is why we are so interested in “Earth-like” planets which are big enough to have strong gravity, are the right temperature to allow liquid water, and have solid surfaces allowing water to pool and to provide the other elements that life might need.

Note that it is possible that life might be able to exist in a wider variety of conditions but I’ll stick to these, fairly conservative, assumptions.

Even when all the conditions are just right, or within certain limits, it’s hard to know how often life might arise. Experiments in the lab and some observations of molecules in space indicate it might be really likely, but the failure to find life on Mars seems to contradict this.

But even if there was only one chance in a billion of life arising if conditions were suitable, that still means these should be a lot of it in our galaxy alone, and a lot more in the universe as a whole.

There are about half a trillion stars in our galaxy (although this number has gone up and down a bit, the latest number I heard was at this high end) and each star seems to have multiple planets (let’s say 10 as an approximation) and it’s likely that at least one might be in the correct temperature zone (some stars might have none in this zone but other, like Trappist-1, have many). This seems to indicate that there are as many Earth-like planets as there are stars.

A recent Hubble survey indicated there might be 2 trillion galaxies in the observable universe. So we have 2 trillion galaxies x 500 billion stars x 10 planets x 1/10 Earth-like, giving one trillion trillion places where life might evolve in the observable universe.

These numbers could be off by many orders of magnitude but who cares? Even if we are a billion times too optimistic that still means a thousand trillion places!

I have talked about the Fermi Paradox – the fact that according to best calculations there should be a lot of advanced life around, yet we never see it – in previous blog posts so I won’t go into that again here except to say we aren’t much further ahead in resolving it!

There is hope though. As telescope technology advances there will be techniques available which seemed impossible in the past. Detecting a planet orbiting another star is an incredible achievement in itself (the stars are really big and bright but at the distances of other stars the planets are very dim and small). But it should be possible to actually study their atmospheres in the future by analysing the light shining through the atmosphere from the star.

In that case it should be possible to learn a lot more about conditions on the planet (temperature, pressure, what elements are present, etc) and to even detect the chemical signatures of life.

And there are even serious proposals now to design small, robotic spacecraft which can be sent to close stars in a reasonable time (by reasonable here we mean decades rather than tens of thousands of years needed by current spacecraft). We know the closest star, a mere 4.2 light years (42 trillion kilometers) away, has a planet but it is unlikely to be suitable for life, but other relatively close stars could also be explored this way.

So how long will it be before we know that life exists on other planets? I predict hints of its existence within 10 years, strong evidence within 30, and proof within 50. And at that point, depending on the circumstances, it should be obvious just how likely life is. I predict we will start finding evidence for it everywhere.

But I still can’t get past the problem presented by the Fermi Paradox. If life arises frequently, why don’t we see signs of advanced, intelligent life? Maybe intelligence isn’t a good evolutionary trait. And, especially given the state of the world at the moment, that is a worrying thought.

Life’s Just a Game

July 5, 2016 Leave a comment

Is life a game? Is the whole universe just one big game or simulation? It’s an interesting question and one which might not be quite as frivolous as many people think. Before I explain why, I should revise a few of the common musings on the subject often found on the internet.

First there’s this one: Yes, life is a game. And according to the laws of thermodynamics, there are four inviolable rules: Zeroth: You must play the game. First: You can’t win. Second: You can’t break even. Third: You can’t quit the game.

The first and second in particular do reflect the real rules of thermodynamics quite well. Very crudely put, the first says that energy cannot be created nor destroyed, it can only change forms, and the second law says the entropy (simply put, the amount of disorder) in a system will increase.

Then there’s this idea from the arts: “All the world’s a stage, and all the men and women merely players: they have their exits and their entrances; and one man in his time plays many parts, his acts being seven ages.” – William Shakespeare

But what about more serious, scientific and philosophical thoughts on the subject?

Recently, I read that Elon Musk thinks that we are probably characters in some advanced civilisation’s video game. In other words, he thinks life is a game. This isn’t a new idea, despite some of the news outlets making it seem like Musk is onto some new, brilliant form of ontological understanding of our most basic existence. In fact, the idea goes back at least 60 years in fiction and was discussed in a serious way by philosopher Nick Bostrom in a 2003 paper called “Are You Living in a Computer Simulation?”

Yes, I realise that a simulation is not necessarily a game and vice versa, but many games do involve simulating of the real world (combat simulators, flight simulators, etc) and the distinction isn’t important to the main point here. Maybe Musk thought that saying we are part of a computer game just sounded a bit cooler!

So what is the simulation hypothesis all about? Well, first I will present it in my own way which seems to lead to the conclusion that the simulation exists…

The universe is a big place, perhaps the biggest (according to author, Kurt Vonnegut) so we would expect that there must be many more places in the universe, apart from the Earth, where life, and intelligent life, has arisen.

We might also expect that in many places that intelligent life has advanced to a point far beyond where we are now. After all, the universe is 13.8 billion years old and humans (in the current form) have only been around 0.001% of that time. Surely other species on other planets became intelligent and capable of advanced technology far before we did.

We would also expect that computer technology would be an important part of any technological culture’s abilities. Since computers have only been around for 70 years and have already advanced to a remarkable level, we would expect that more advanced civilisations would have computer technology billions of times more capable than ours.

We have already reached the point where some simulations are almost indistinguishable from reality so those far more advanced systems might actually be literally indistinguishable from, or at least so close to reality that it would be almost impossible to tell the difference.

These advanced races with computer systems capable of creating artificial realities would probably want to model universes which would be virtually indistinguishable from real universes.

There might be many of these artificial realities and perhaps only one real reality.

So why should we think that our reality is the real one when it is far more likely to be one of the artificial ones?

In other words, it is just common logic to accept that we really do live inside a simulation, or, to put it another way, life is just a game!

Bostrom presented the idea in a different way which lead to three possible conclusions, one of which (and the one which some people think is the most likely) was the same as mine, above…

Given all the points I have already made, he thought that one of these three conclusions must be true…

1. Either “the fraction of human-level civilizations that reach a posthuman stage (that is, one capable of running high-fidelity ancestor simulations) is very close to zero”. In other words, there are almost no advanced civilisations capable of running these simulations.

2. Or, “the fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero”. In other words, the advanced civilisations exist, but they don’t want to run the simulations for some reason.

3. Or, “the fraction of all people with our kind of experiences that are living in a simulation is very close to one”. In other words, we live in a simulation.

Here are a few interesting points Bostrom makes about his idea…

1. He isn’t claiming we live in a simulation. He just presents that as one possibility. He has said he thinks the likelihood is about 20% (but then adds “perhaps” and maybe”). He also notes that people who hear the argument usually think that one of the three conclusions is obviously true, but that there is no consensus on which one!

2. He also notes that people who claim to have experienced odd (supernatural, for example) phenomena should not claim these as evidence of glitches or bugs in the simulation. We would expect this sort of thing occasionally, even if our universe is real, simply because of mis-reporting and misunderstandings.

3. Maybe the most important point Bostrom makes is regarding whether the idea can be tested or not. One way would be if the aliens running the simulation wanted to show us that it existed. A phenomenon impossible in the natural world might occur (but see 2 above) making it clear our universe isn’t natural. Or we could reach a stage of technology where we ourselves could create a simulation of this sort. There’s no reason why one simulation couldn’t run a second one.

And if we reached an insurmountable problem which prevented us reaching a more advanced state (total destruction in a nuclear war for example) or we realised that there are fundamental limits on simulations which can never be overcome, then this would be evidence against the simulation option being true.

4. Bostrom doesn’t see any direct connection between the hypothesis and religion but there is an undeniable indirect connection, especially in relation to intelligent design. He quotes one atheist as saying this is the best evidence for God yet!

And finally, these are my additional thoughts on the subject…

1. I put this in a similar category to the search for extraterrestrial intelligence (although its scope is even greater, of course). But like SETI we are working with very little initial data. Of course, Bostrom is a philosopher, not a scientist, so we shouldn’t necessarily expect the same level of rigour as we would from science.

2. There are several major (and a few minor) assumptions we must make in order for the idea to even pass the first stage of appraisal. First, there must be life elsewhere in the universe; second, life must reach a level of intelligence where advanced technology is possible; third, computer technology must be capable of creating a simulation of sufficient accuracy that it is virtually identical to reality (whatever that is); and finally the “sims” must gain consciousness (whatever that is).

3. Most simulations have a degree of “granularity” where, if you look with sufficient precision, you will see a limit to their accuracy. You will reach a “pixel” size which cannot be divided any further. Well, I must mention the Planck length and Planck time here. These can be interpreted as the basic units of space and time in our universe, just like we would expect in a simulation!

The Planck length is 1.61 x 10^-35 meters, which means the resolution of our universe is about 4 billion trillion trillion dots per inch. Sure sounds like a simulation – and a very good one – to me.

So yes, it looks like life really is just a big computer game. Can we have a reboot?

God Did It

June 17, 2016 33 comments

One of the most common tricks that religious people use to escape the fact that their beliefs have been refuted by scientific knowledge is to try to assimilate the new ideas into their own, but add the element of divine intervention.

Here’s an example: Traditionally Christians have believed that life was created by God in a few days and that nothing much has changed since then. But since the Theory of Evolution was developed and since the extraordinary amount of evidence supporting it has been discovered that original myth is no longer viable. So now a common response (apart from just denying the facts as many fundamentalists do) is to say “Sure, evolution is true. That’s how God works with life”.

Another example might be the origin of the Universe. The Bible gives an account of this in Genesis and that’s exactly what people believed until science uncovered the real facts regarding the Big Bang event about 13.7 billion years ago. So the Christians (again, those who don’t simply deny the overwhelming evidence) now say “But who started the Big Bang? Of course, it was God”.

In reality, this brand of believer (it’s not just Christians) could summarise their ideas in three simple words: “God did it”.

I recently heard an interesting analogy. When I walk into a room and turn on the light most people would accept that closing the light switch simply allows the electricity to flow to the bulb which then emits light. But using the “God did it” gambit I could say instead that the “Light Fairy” did it. Flicking the switch is simply a signal for the fairy to do her magical work and provide me with light.

What I’m saying is that God and the fairy aren’t necessary. Adding that extra element provides no extra level of knowledge we didn’t already have. It just makes things unnecessarily complex.

In addition to this it is entirely arbitrary. If we were going to add an extra layer of control to evolution (or any other phenomenon) why should it be God? Why not advanced aliens? Or psychic powers? And if it is a god, then which one? What’s so special about the Christian God? Could it be Thor or Zeus instead?

Some people say there are particular aspects of these processes which indicate a supernatural power must be involved. After all, how could a “blind” process like the naturalistic form of evolution lead to advanced life? Wouldn’t a “guided” form be more likely?

Well no. Let’s look at how evolution has worked. Over 99% of species which have existed in the past have gone extinct. Does that sound like how a god would operate? It seems very inefficient to me. But let’s just say that is a viable process for a god to use. What would have happened if we found the exact opposite: that every species was successful? That would have sounded even more like a god, wouldn’t it? And, no doubt, the religious people would be pointing out how their god was responsible.

So it doesn’t matter what the facts are, the “God did it” hypothesis can be invoked and it can never be proved wrong. It can’t be wrong, because it isn’t something that can be tested. But because of that, it can’t be right either. It’s actually worse than something that is wrong.

If we test evolution instead we can find many ways it might be wrong. If every species was successful evolution would immediately be disproved because elimination of some species while others survive is its main mechanism. If one type of life didn’t lead to another through gradual change evolution would also be disproved because small mutations being selected and eventually dominating is an evolutionary mechanism.

And what about the Big Bang? Well for it to be true there has to be some precise observations which agree with theory. The universe has to be expanding, there has to be certain abundances of elements, there has to be background radiation left over from the initial expansion, and several other more minor points. So what do we find? Well all of those requirements are satisfied, including a cosmic microwave background exactly as expected if the Big Bang is true.

But God could still be involved, right? Maybe the cosmic microwave background is just a remnant of the process he used. Sure, maybe. And if there was none then God could still be involved. And if the temperature had been 1 or 5 or 100 or 500 instead of 2.72548 then maybe that was the sign of God. Again, anything is possible because “God did it” is just not a theory.

Not only is it not a theory, but it is nothing. It’s a childish, meaningless inanity which isn’t even worthy of discussion – yes, I understand the irony in the fact that I have just used a blog post to do just that!

If anyone wants to use this in a serious discussion then we need a few details. You know, the sort of details which science gives us, like when, how, or where God did it. Then we can do some serious testing and see whether there really is any merit in the idea. Until then, these religious types should just keep the silly fairy tales where they belong and let the adults get on with the real discussions of reality.

Bordering on Impossible

May 7, 2016 Leave a comment

I have mentioned my admiration for the LIGO project before but since then it has actually achieved its goal so now might be a good time to discuss it again.

First, what is it? Well if you haven’t heard the news (if you haven’t you obviously don’t follow science news at all) and haven’t read my previous post on LIGO (titled “Ripples in Space-Time” from 2015-11-10) here’s a brief summary…

LIGO is an experiment designed to detect gravity waves.

It consists of two detectors – one in Washington and one in Louisiana – which consist of two 4 kilometer long tubes, containing a high vacuum, at right angles to each other. A precision laser shines down the each tube and is reflected back to the central point.

If a gravity wave hits the experiment it warps the detectors (to be precise it warps the space-time the detectors occupy) very slightly and that can be measured by changes in the light beam, specifically by how the two beams interact. When there is no gravitational warping the two beams are in phase but if one is warped the beams interfere.

The reason there are two detectors (each with 2 lasers) rather than one is that local effects (traffic, small earthquakes, etc) can affect them far more than gravity, but these will only affect the nearby detector. Gravity waves will affect both (with a tiny interval of time between them).

It sounds simple but the complicating factor is the size of the effect. Imagine trying to measure the size of something to a precision of one part in one hundred million trillion. That precision can never be imagined in relation to normal size objects so let’s compare it to the whole planet Earth.

The Earth is about 13,000 kilometers in diameter so to measure it with the same precision the measurement would need to be accurate to 0.00000000013 of a millimeter. If a single grain of sand interfered with that attempted measurement it would distort the measurement by a factor of 8 billion times too much. In other words, the precision is equivalent to measuring the width of the Earth accurate to one 8 billionth the width of a grain of sand.

A good phrase to describe the staggering difficulty of this task was “bordering on impossible”. In fact, many people thought it really was impossible. But it wasn’t. Because gravity waves were actually discovered at LIGO near the end of last year and officially announced earlier this year.

And there are a few interesting details of the discovery which make it even more incredible. Here’s an overview of some of them…

The gravity waves which were detected were created in an event where two large black holes, each 20 to 30 times the mass of our Sun, merged. This happened 1.3 billion light years away which means it happened a billion years ago and the waves had taken that long to get here. The event was translated into a sound which has been described as a “chirp”. It lasted just 0.2 of a second.

The detectors had been upgraded and had just been switched on again. An scientist in Germany first saw the signal and thought it might just be a test because there had been extensive testing of the new system up until then. But he soon found it wasn’t and the timing of the event in the two facilities clearly showed a real gravity wave which could even be isolated to a line through the sky. The collision happened somewhere along that line.

If a third detector had been available the position could have been deduced by triangulation but unfortunately a third device in Europe which might have been used was being maintained. But hey, you win some and you lose some, and finding the event at all so quickly after an upgrade was a big win in itself. After all, massive black holes don’t collide that often!

So what does it mean?

Well the observation finally confirms a prediction of Einstein’s General Theory of Relativity which was published exactly 100 years prior to the confirming observation. Of course, many other aspects of the theory have already been confirmed but gravity waves were one of the few that hadn’t. Relativity really is a remarkable theory and its predictive ability has never failed.

Gravity waves now allow astronomers to look at the universe in a whole new way. Instead of using electromagnetic radiation (light, radio waves, x-rays, microwaves, gamma waves) some super-energetic events can be observed using their gravity radiation.

And the confirmation of Relativity further strengthens its role as one of the core theories in physics. It is a theory related to the most basic levels of reality so there are few obvious practical benefits, but fundamental theories are what everthing in our modern, technological society are based on, so their importance cannot be overstated.

And like all great technical achievements which push the extreme boundaries of technology (the space program being the most obvious) there will be spin-offs from the actual construction of the facilities which will be used in diverse areas of technology in the future.

So yes, LIGO is an astonishing technological tour de force – on a similar level to the LHC, the Apollo program, and the Hubble Space telescope – something that every human on the planet should be truly proud of.

It’s All About Balance

November 22, 2015 Leave a comment

Most people can understand the concept of opposing ideas: of positives and negatives, of good and bad, of inputs and outputs. For example, they wouldn’t consider the idea of me giving them $100 good if they knew I was also going to take away $110.

But almost everybody fails to take this idea to its natural end point, because they don’t look at both sides when they are considering a political, social, or philosophical point. They tend to only look at the side of the issue which suits some pre-conceived, intuitive idea of what the answer should be. And this applies to the political left and right, to old and young, even to intelligent and ignorant.

Let me give you an example. I met a reasonably intelligent person at the pub last night who turned out to be a young-Earth creationist. Yes, I have managed to avoid debates with creationists for a significant time, in fact it has been 16 months (a blog post titled “Not Even Wrong” from 2014-07-19) since I mentioned it as a major theme in this blog!

But all good things must come to an end. Actually, to be honest, I love debating creationists. It’s just so entertaining to watch their convoluted maneuvers trying to defend something which is essentially indefensible!

But back to the main theme here: balance. Here’s the sort of thing I hear from the more sophisticated defenders of unreality: they point out minor problems with opposing theories (for creationists this is just about everything: big bang, evolution, etc) without looking at the vast bulk of evidence which disagrees with their perspective.

So they will quote (often out of context or incompletely) a well known scientist and claim that indicates doubt about evolution, but they will ignore the hundreds of quotes supporting evolution. If quoting someone is sufficient to support your side (a doubtful proposition anyway) then surely quotes from a hundred people against your views should also be considered. But they’re not.

Or they might find some small areas of doubt in a theory, or some aspect of a theory which was shown to be genuinely incorrect or inaccurate but later corrected, but they will ignore hundreds of times where the theory was shown to be accurate and where it predicted the real world precisely. Again, if a weakness in a theory can be assimilated into a person’s opinion on science then it’s only fair (and logical) to look at the strengths as well.

People who have irrational worldviews also seem to have a lot of problems (perhaps deliberately) with assessing probability. Here’s an example: if we find that light has been travelling from distant galaxies for billions of years which is more likely: that the galaxy has been there for billions of years producing light or that it was created in some unspecified way with the light already travelling through space?

The “travelling light” theory is possible but surely it is extremely unlikely since we have zero evidence of it ever happening. But that’s the sort of incredibly unlikely thought creationists will cling to while totally ignoring the far more likely possibility that the universe is simply billions of years old.

Finally, creationists often seem to have trouble appreciating the strength of multiple independent sources of evidence. There is overwhelming evidence from completely independent areas of knowledge: astronomy, physics, biology, geology, history, archaeology, and many others showing the universe is old. But they prefer to believe a single source of extremely doubtful accuracy instead. Where’s the balance in that?

I know that by picking on (young Earth) creationists I have attacked the easiest target because their beliefs are simply absurd and many other groups have far more sophisticated, and difficult to refute, beliefs. But the process is the same, even if slightly less obvious: it’s all about balance.

Ripples in Space-Time

November 9, 2015 Leave a comment

Different people have different opinions on what are the most extreme and audacious activities our civilisation is involved in. Some think it is courageous and risky ventures in the business world, some think it is the production of great art, and some think it is impressive engineering projects.

I tend to admire our efforts at great scientific achievements most. In the past I have blogged about the Large Hadron Collider which I think is arguably our greatest scientific project ever (note that the engineering world shares substantially in this achievement) and this time I want to talk about another large scale project which also makes measurements with (literally) unbelievably exquisite precision.

The project is called LIGO, which stands for “Laser Interferometer Gravitational-wave Observatory”. As the name suggests, this is an instrument (in fact 2, situated in Louisiana and Washington, USA) designed to measure gravity waves, and there are several other similar installations trying to do the same thing in other locations around the world.

The LIGO observatory consists of two tunnels in high vacuum, each 4 kilometers long and at right angles to each other. A laser is split and directed down the two arms and then reflected back with mirrors. As the two beams arrive back they interfere with each other and this can be used to measure the lengths of the two arms very precisely.

Why would they want to do this? Well, Einstein’s Theory of Relativity predicts the existence of gravity waves which are “ripples” in space-time which travel out (at the speed of light) from events where mass changes configuration. The problem is that these waves are weak. Very weak. Even a massive catastrophic event like a star collapse only generates very small waves.

To detect these waves as they reach Earth it is necessary to measure how time and space is warped. Depending on the location of the source one arm of the tunnel at LIGO would be warped one way (it might get longer) and the other would be warped the opposite way (it would get shorter).

So that seems simple enough but the problem is how much the length changes. The effect which is trying to be measured is just one thousand trillionth of a meter over the 8000 meter journey of the laser. That’s like measuring the distance around the Earth accurate to about one 10 billionth the width of a single hair.

Here are two other ways to visualise the tiny size of the distortion: a 1 km ring would deform no more than a one thousandth the size of an atomic nucleus; and it’s like measuring the distance from the Earth to the Sun to the accuracy of the size of a hydrogen atom.

When I first read these numbers I thought I had misinterpreted them because it’s almost impossible to believe that anything can be capable of such an astonishing feat of precision. But it’s true according to several different sources.

Apart from simply how small the measurement is here are many factors which have to be considered. Even the tiny vibrations caused by traffic on distant roads is much greater than the distortion caused by gravity waves, for example. But this problem can be overcome. First, the two tunnels at right angles would warp in a particular way specific to the effects of gravity waves. Also, the two installations thousands of kilometers apart would both detect the gravity waves but would be affected differently by local noise.

So if one LIGO detected an event but the other didn’t it would be assumed that it was due to local noise. But if both detected compatible events then a gravity wave is the best candidate for the cause. In addition, by timing when the event reached each observatory the direction the wave came from can be investigated.

For example, if the wave hit the Louisiana observatory before Washington then the event would have come from that direction. Of course, moving at the speed of light, the difference in time is small (a maximum of 10 milliseconds), but that’s easy to measure compared with the other stuff being done there.

Finally I have to answer the obvious question: so what, who cares about gravity waves, and what practical purpose do they have? This is the question scientists hate, for two reasons: first, the pursuit of knowledge in itself is sufficient justification for this work; and second, discoveries which seem purely theoretical almost always have practical benefits later.

So the billions being spent on this should not be thought of as a waste of time and money, or as just a pet project for boffins, or as an expensive exercise in gaining theoretical and useless esoteric data. It should be seen as a way to learn more about the most basic attributes of the universe; of potentially gathering knowledge which can be used in future technology; and most importantly of all, as a way to do something which is just really cool!