Just how big is everything

"Space is big, really big, you just wont believe how vastly mind bogglingly huge it is. I mean you may think its a long way down the street to the chemist but that's just peanuts to space. Listen....."

A word of caution this article contains really big numbers so I will use some simple scientific notation, it looks like this 1*10^2 which basically means 1 *10 *10 or 100, another example 5*10^3 would be 5*10 *10 *10 or 5000 (basically it is the first digit followed by a number of zeroes matching the number after the ^) also each of the units below is a thousand times larger than the one before it.

one, thousand, million, billion, trillion

The simplest to expalin unit of measurement used on the scale of galaxies or the universe is the light year, so I will use that. Light (in a vacuum) travels at 3*10^8 meters per second or 300 000 Km per second, for scale the earth is only around 12 700Km across. A light year is the distance travelled by light in a vacuum in one year and is about 10 000 000 000 000 or 10 trillion Km, the nearest star to our sun is around 4.5 light years away, our galaxy 1*10^5 light years across and the visible universe 9.2*10^9 light years. An interesting point to mention here is that obviously the light we receive shows us what these objects were like when the light left them, as such we see things as they were millions or even billions of years in the past. This means very distant galaxies look very different from near ones and the limit of the observable universe is caused by seeing back so far in time that the light at this distance was emitted long before any stars formed at the point when the universe finally became cool and spread out enough for it to be able to transmit light.

The visible universe (as far as we can see) contains a minimum 170 billion(1.7*10^11) galaxies, the smallest of which contain around 10 million(1*10^7) stars and the largest 100 trillion(1*10^14), giving a low estimate of around 1700 000 000 000 000 000 000 stars in the universe.

Take a few minutes to get your head around these numbers and watch this video attempting to show the length scales involved and this one demonstrating the relative sizes of some of the stars in our galaxy. Each of those behemoths is to the naked eye at most a single dot of light or completely invisible due to the shear distance between Earth and it. Some of those minuscule points of light in the sky every night are even entire galaxies, a hundred billion glowing giants so far off that combined they are barely even visible and most galaxies are utterly undetectable without incredibly powerful telescopes. If we then turn that logic on its head we get this, and bearing in mind that the photo was taken from near Saturn, a distance which is less than insignificant on a galactic scale. Understanding just how small our world is is one of the most incredible and humbling experiences I can think of.

Opening quote taken from The Hitchhikers Guide to the Galaxy by Douglas Adams, everyone should go read it.

UFOs and aliens

First things first yes I believe in UFOs (iv seen one myself) and aliens, however there's a catch here. UFO stands for unidentified flying object, therefore any object in the sky the observer can't identify is by definition a UFO. Further since most observers are average people and less than familiar with weather balloons, unusual clouds, secret military aircraft, meteorites and who knows what else, combined with the fact that the sky, especially at night, has no reference points so even familiar objects at an odd angle may be unrecognisable means anyone who jumps from "I saw a UFO the other night" to "the spaceship was X big and moving at Y speed" is very likely mistaken. I say this in part because there has never been a sighting where experts could distinctly say yes that is a space ship, its always mistaken identity, a hoax or such crappy quality no-one can tell, and also getting between solar systems is really hard and takes bloody ages(yes that is the "technical term" for the time frames involved).

As discussed in my last post the speed of light in a vacuum is 300 000Km a second, this is also the universes absolute speed limit, nothing can travel through space faster, even stuff like magnetic fields and gravity are restricted to this limit. Star systems are also really far apart, our nearest is 4.24 light years away so a round trip would take a minimum 8.5 Earth years. Even if aliens are common they are still unlikely to live that close by and this speed is incredibly difficult to even approach so a more realistic time-frame would be anything from 50 years upwards with 100s certainly not being unreasonable. After that much effort any species with sense would either make its arrival well known and get friendly with the natives or actually be competent at staying hidden.

On a related point claims of direct contact always involve aliens that are basically human in appearance, this is laughably improbably The body shape has only evolved once on this planet so in our environment there are plenty of other designs that allow life to get along just fine, on any other planet there will be dozens of working body shapes and as many as you like that would have worked but never evolved.

So that's the UFO bit out the way, they are non alien objects people fail to recognise but I also said I believe in aliens and that's because as mentioned in my last post there are absolute shitloads(another "technical" term) of stars, roughly in the region of 10^21. Even if the chances of life developing around a star chosen at random are a billion to one that gives hundreds of inhabited planets in our galaxy alone, and a number in the trillions across the whole universe. To think that the only planet in the entire universe hosting any sort of life is our own is the most incredibly arrogant thing I can imagine.

Think mistaking clouds for spaceships is silly, think again

Next time SETI and the Drake Equation, then the space stuff gets a break.

Proving the shape of the Earth

Well this is a few days later than I wanted it to be due to a combination of exams and my house-mates dragging me into various LAN games but as promised a post about how to prove the earth is spherical-ish even with 2000 year old technology. But before that here is an article I found a few days ago that would have gone nicely with my previous post.

The first and simplest to argue evidence would be launching into space and seeing for yourself, a few orbits should convince anyone but that's not an economically sound idea and certainly wasn't possible 2300 years ago when the idea first cropped up. A less impressive alternative would be to look out over a vast flat landscape from a plane or high mountain, they would also put you high enough to see the curvature of the Earth.

A more intellectual argument was proposed in the early 1600s when two important details had been understood, first the heliocentric system proposed that the sun is at the centre, thus the Earth is another planet. Second, with the invention of telescopes moons were seen around Jupiter showing the other planets were spherical (and later on sufficient detail was possible to directly see the planets rotating and since they were circular at all times spherical), so Earth probably is as well. Not entirely satisfying but a nice piece of logic none the less.

Another interesting argument comes from an understanding of gravity, the net attraction of a body pulls an object towards its centre of mass, thus if you have a ball anything on the surface is pulled directly into the surface but if you have a disk objects near the edge are pulled sideways with only a small downwards component. We have all herd stories about falling off the edge of the world but who has herd about magical forces dragging people back towards the centre or (since they would assume gravity was still directly down)land that keep getting steeper until it is unclimbable. Another interesting effect would be that all the water on the Earth would be pulled into a partially flattened dome over the centre.

Now for some ancient direct observation, if you were to climb a mountain(the higher the better) near a plain or the ocean and look out over it there would be no obstacles so on a flat earth you would be able to see to the next mountain range or the edge of the Earth, whichever came first. That doesnt happen and since it was possible to observe people coming from distant lands from the top of the mountain long before they were visible from the bottom of the mountain the Earths surface is clearly curved. The increased elevation would allow visibility of a greater proportion of the surface (put a blob of blutac on a football then keeping your eye as close to the ball as possible turn it until the blob is no longer visible. Then move your head directly away from the ball and it will become visible) but it is possible to go one better than that. If you know the height of the mountain and take a protractor to the top then measure the angle from horizontal to the horizon it is just a case of simple trigonometry to find the radius of the Earth. This method is so effective that in the Masudi Canon, Abu Rayhan Biruni(973-1048) calculated the radius to within 16.8km of todays accepted value. That was about 600 years before the Western world was even in the ballpark.

a few more proofs

website of the flat earth society, all the arguments are flawed in premise, logic or what it would mean but its kind of interesting. If you cant spot one of the mistakes ill be happy to point it out.

As always anything you don't understand, want to clarify or think is incorrect either research it yourself or comment and even if its years from when I wrote this ill get back to you as soon as I can. After all "its better to be corrected and look the fool than remain ignorant and be a fool forever", can't remember who said it and its paraphrased but you get the idea.

Earths shape

I was revising for an exam the other day in the physics resource room and somehow we ended up having a short conversation about conspiracy theorists and the one name I remember cropping up was the Flat Earth Society. So I have decided to do a bit of a rant/proof on this. This post will just be a bit on the shape of the Earth and I will go into the evidence later in the week.

Long ago people assumed the Earth was flat, perfectly reasonable since apart from all the hills and valleys no overall curving trend was observable to the people at the time living their day to day lives. Even today a flat Earth is a sufficiently good local approximation for people who don't travel exceptionally long distances, although there are plenty technologies that do rely on it to work but I'm discussing direct observation at this stage so that's beyond the point.

Things started to change around 330BC when the first evidence started to emerge for a spherical Earth, this was an important discovery because long distance navigation such as crossing oceans is going to be substantially different depending on if the ocean is flat or curved and yes by the time Columbus came along everyone knew full well the Earth was certainly not flat, give the people of the time a little credit.

That is all well and good and for most of us this will be the most accurate model we need but it is not the end of the story, a more accurate picture, and one important for satellites was first proposed by Newton in 1689. Since the Earth rotates there will be a 'centrifugal force' that will push the material outwards more strongly the further it is from the axis of rotation(actually its not a force as such, just inertia, the material further from the axis is moving faster so it is harder to change its direction). The end result of this is that the radius of the earth to one of the poles is 6 356.8km but the radius to the equator is 6 378.1km. This means the polar diameter is about 40km less than the equatorial diameter, this slightly flattened sphere is called an oblate spheroid.

It is even possible to make more detailed observations which have found that the South pole is 40m closer to the centre of the Earth that the North pole, so it actually has a very slight pear-shape, with various lumps and dents roughly matching the continents and oceans. However having said that its relative variations from an oblate spheroid(0.17%) are less than a pool ball from a perfect sphere(0.22%).

All that is actually a nice example of how science works, start with a basic idea, such as "as far as I can see directly the earth is flat" and then develop the idea "actually its a sphere it just looks flat when your standing on it because its bloody huge" and further development "wait its a slightly squashed sphere" and this continues to whatever accuracy is needed. Since the maths involved gets evil very fast as the idea is refined the secret is to use the simplest model that is detailed enough for the task at hand. Treating the Earth as an oblate spheroid is vital to keep satellites where they are needed, but its a bit of a headache when you just want to find somewhere on a map of your town, at that level even the gross oversimplification(to the point of outright wrong) of a flat Earth will do the job. Of course the key point of it being science it you also have to prove the ideas.

http://www.scientificamerican.com/article.cfm?id=earth-is-not-round an article covering spherical Earth onwards

http://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-002-physics-and-chemistry-of-the-terrestrial-planets-fall-2008/lecture-notes/MIT12_002f08_lec27_28.pdf the kind of maths involved in getting this lovely detailed understanding of the Earths shape.

logic puzzle

I think its about time I made a much less serious and more light hearted post so here goes.

This is a really good puzzle one of my friends gave me a couple of years ago, be warned its not for the faint hearted.(expect to spend at least a couple of hours racking your brains before you get a working solution)

You have 12 identical looking weights, 11 are the same weight one is slightly different (you can't tell the difference by hand), there is also an old style balance scales (think the star sign Libra). Using only three weighings devise a system where you are guaranteed to find which weight is different and if it is lighter or heavier.

Also all weights being tested at any given time must be places simultaneously so no cheating by putting one on each side then adding pairs until it goes off balance and calling it one weighing.