Archive for July, 2009
Pig and Pepper
I recorded a new song today, it’s called Pig and Pepper, it’s the 6th in the Alice in Wonderland set of songs and is available to download FOR FREE RIGHT NOW on the music page.
Basically it’s interpretting the 6th chapter as being a moment of indecision, not being sure which path to take, then regretting it once you make the decision. You know the story.
GO LISTEN.
And comment this post to tell me what you think.
(all 3 of you)
The Physicists Favourite Thought Experiment
A recent post on a forum I visit got me thinking about this idea.
First, imagine you are on board a high speed train and you have a gun. This isn’t Murder on the Orient express though, this is an experiment.
Say the train is moving at the same speed as the gun can fire a bullet (assuming this speed is the initial velocity of the bullet and the train is moving in a vaccuum, so air resistance is negligible), call this 500 m/s.
Now, fire the bullet out of the window directly ahead. What happens?
Well, without air resistance the bullet isn’t limited by terminal velocity, so the bullet is moving at 500 m/s before it is fired, then gains an extra 500 m/s once it is fired. The bullet is moving at 1000 m/s. Or, with respect to the passenger on the train, the bullet is moving at 500 m/s.
Now, point the gun directly backwards, away from the direction of motion and fire. Again, relative to the passenger the bullet travels at 500 m/s, but relative to an observer standing by the tracks, the bullet appears to be falling straight down.
Then that got me thinking about a similar problem that is all too common in Physics classes.
Imagine you are on board a spacecraft travelling at the speed of light.
You have a torch, you point it in the direction you are moving and turn it on.
What happens?
Well, the light travels away from you at the speed of light.
Now, what about a stationary observer? (that is, the spacecraft is moving relative to the observer)
Nothing can travel faster than light, right?
Right.
Well, the observer also sees the light travel at the speed of light in the direction the craft is travelling.
But then the observer would see the light moving at the same speed as the craft, yet the craft sees the light moving away at the speed of light.
A contradiction?
That’s where Einstein comes in with the Special Theory of Relativity.
This states that light moves at a constant velocity relative to all observers, irrelevant of their velocity or direction.
This is allowed to happen by a phenomena known as time dilation. That is, time slows down the faster you get.
This then leads to the famous ‘twin’ thought experiment.
Take a set of twins, give them identical clocks, leave one on Earth and set one off on a journey round the Universe at very, very high velocity.
When the travelling twin comes back, his clock will be lagging behind the stationary twin on Earth. Thus, he has aged less.
Time dilation is a very interesting concept of both Special and General Relativity, and has had a profound impact on modern Physics, even modern life. In fact, GPS satellites orbitting Earth must take into account relativistic effects, something called gravitational time dilation, when sending positioning data.
A Space Odyssey
Posted by Tom in Astronomy, Science, Technology on July 28th, 2009
It’s been 40 years since the Apollo missions and the first manned lunar landings and I, for one, have been watching the TV programmes quite a bit. It’s all the same old knowledge though, filled with things everyone already knew. The crew of Apollo 11 underestimating their position and having to land in precarious circumstances, the cancellations of the later Apollo missions due to lack of political will, the more recent US revival in space exploration by ‘Dubya’ and his directing NASA to get a man on Mars in the next few decades.
What I found more interesting was the missions planned by other nations. Particularly China.
OK, so many people know that China have a lunar exploration programme. Many people know that China plan to land men on the moon around 2020/30.
What I didn’t know was that following their manned missions, China will begin construction of a permanently occupied lunar base!
If this did happen, it would completely change space exploration. I’m thinking along the lines of 2001 here. Minus the evil computer.
Whoever decided to build an extremely powerful artificial intelligence and give it a BRIGHT RED EYE anyway?!
A lunar base would not only be exceedingly cool, but would offer a ‘recharge station’ for spacecraft going from Earth to more distant destinations, not needing anything like the huge rockets required to take a craft to the escape velocity of Earth. Taking off from the Moon would be a much easier task.
Hopefully once it’s all completed the Chinese will share their lunar base with the other nations, perhaps there’ll even be an Earth-wide space exploration programme and all of the political agendas involved in space exploration will be gone. Maybe I’m wishing there though.
None of this is fully OFFICIAL yet, but the renewed interest in space exploration is definately a good sign of things to come!
Further reading:
Close to ready
I’m currently finishing up recording and mastering another full albums worth of electronic music.
Tentatively titled ‘Introspection’, it contains 8 tracks, all of which have previously been available to download in the Music section, but have currently been taken down while I polish them all and finish everything up.
Here’s some artwork.
Track listing.
1. Start
2. February
3. Meridian
4. Krystaal
5. Untitled part 1
6. The Endless, Repeating Cycle (Untitled part 2)
7. Recreate
8. Finish
R.I.P Stirling Engine
Posted by Tom in Science, Technology on July 27th, 2009
Ok, it’s official. I am rubbish at building Stirling Engines…
It doesn’t work, despite extensive testing and the use of THREE candles to heat it.
The Stirling Engine project is dead. This saddens me.
At least it gave me something to do for a few weeks.
Stirling Engine Part 2
Posted by Tom in Science, Technology on July 25th, 2009
Stirling Engine number 2 is completed and it seems like it may work. Everything is as airtight as can be, the balloon pops in and out when the piston moves so hopefully it all should work.
Initial testing was less than encouraging though. The crankshaft seems to meet a bit of resistance in its cycle and prefers not to comply with gravity and let the piston fall from the uppermost position. Creases that need some ironing out.
Possible explanations for the poor performance in initial testing:
1. The heat isn’t great enough. I was only using one small tealight candle and, while it did manage to reach a too-hot-to-touch temperature, it may still not be hot enough. I will try again tomorrow with more candles.
2. The crankshaft doesn’t rotate as smoothly as it should. Perhaps oil would help, maybe an attempt at straightening the crankshaft as much as possible.
3. There is an air leak. Although the positive response when manually moving the piston seems to rule this one out.
4. I am just useless at making Stirling Engines. This one is always in the back of my mind, and if all else fails, this is the most likely explanation. Maybe I’m not cut out to work with hardware and should stick with the software side of things…
The Stirling Engine
Posted by Tom in Science, Technology on July 19th, 2009
It’s a simple enough premise. Take a pressure chamber; a piston that fits snugly, but not too snugly, in it; a diaphragm to force the piston back down and add heat and what should result is a Stirling Engine. It’s not quite as simple as that, it turns out. There are a few designs, but the simplest one is the single cylinder design, as seen here.
This week I started on building one.
My first attempt involved using a standard Guinness can for the pressure chamber, with the top cut off. The top of this chamber is then another Guinness can with the top cut off, then glued to it, so there’s a kind of bowl on top. This chamber houses the displacer piston, which I crafted from a large Red Bull can, again with the top cut off, to make it around an inch and a half high, with the bottom of a Dr. Pepper can glued to it.
From then, it’s a case of drilling a hole in the side of the chamber, gluing a PVC elbow to it, wrapping a balloon over the pipe and adding a crankshaft, with rods to push/pull the balloon (the power diaphragm), and to be pushed/pulled by the displacer piston.
Simple enough?
Well, not quite. It turns out the Red Bull can is too narrow for the chamber, which lets all the air free too easily. Add to that a slightly rushed design and you’ve a recipe for disaster. Or at least a non functional Stirling engine.
Well, at least it LOOKS cool.
Since then, I started on a new design, which I am being a LOT more patient with. I am also replacing the Red Bull displacer with another standard sized can with the top and bottom cut off, cut into a strip, then glued back together to give it a slightly smaller diameter. So far it fit’s pretty snugly in the chamber. Here’s hoping it’ll work this time!
Project: Alice
So I thought this deserved a bit of an explanation.
In the music section, there’s a part titled ‘Project:Alice’, which includes 4 songs at the time of writing.
These songs are titled after the first 4 chapters of Alice’s Adventures in Wonderland by Lewis Carroll. The aim of Project:Alice is to write a song for each chapter in the story, which conveys a message that can be drawn from the chapter. This is done either by interpreting the chapter literally, as in ‘Down the Rabbit Hole’, which essentially retells that part of the story by way of song; by metaphor or allegory, or by parallelling real world events. An example of the latter is found in ‘The Rabbit Sends in a Little Bill’, which draws a comparison between Alice’s confinement inside the rabbit’s house to the confinement of a human within his own mind by a condition known as locked in syndrome. ‘The song of the dead man’ is a reference to Sylvia Plath’s ‘Berck-Plage’, a poem set in a French hospital, which reads: “This is the tongue of the dead man: remember, remember. How far he is now, his action/Around him like livingroom furniture, like a décor.”
A striking parallel to the story of Jean Dominique Bauby, a sufferer of locked in syndrome.
Over the coming months, I hope to complete more and more of Project:Alice, with the eventual goal of completing a full CD’s worth of music and releasing it through this website.
I hope you enjoy the music.
A Fusion of Science and Fiction
Scanning through the BBC Science and Environment news I came across this.
Am I the only one who is reminded of Spiderman 2?
I get frustrated with the way the media portrays some big experiments. Like the link I posted above, the article gives the bold title ‘MAN MADE STAR!!!’. Yes, fusion occurs in stars. The similarities end there really. The conditions in the experiment are completely different, it is controlled, it is on a MUCH smaller scale. It is not a mini man made star.
A similar thing happened when the LHC was in the public eye.
‘CERN TO CREATE A MINI BIG BANG!’
What the hell is a ‘mini big bang’ anyway? There an oxymoron if ever there was one.
This type of headline was all too common around September last year, when the LHC fired its first beam. Even ignoring the above oxymoron, the collisions at the LHC are not simulating the big bang. There’s no singularity of infinite energy density expanding outwards. There’s no inflation. They are just little collisions, each one with roughly the energy of a flying mosquito, which happen to concentrate the energy into a small space.
The whole confusion surrounding the ‘creating conditions just after the big bang’ thing can be summed up like this:
1. Scientists explain that the particle energies reachable by the LHC are as high as the average particle energy shortly after the big bang.
2. The media gets hold of this information and completely misunderstands it, releasing the headline: SCIENTISTS TO RECREATE BIG BANG!
The facts:
The LHC will accelerate protons to around 7 TeV each, smashing them together head on.
The resulting collision will reach energies high enough to create particles that haven’t been seen since shortly after the big bang. This is not the same thing as recreating the big bang. Just like reheating a piece of cottage pie is not the same thing as making a cottage pie from scratch.
A New Game
I came up with a new game today. Chasing thunder storms.
There was a pretty big (compared to our usual standard) storm here today and I was wondering how far it was. So I did the tried and tested method of counting how many seconds between the flash and the bang. It was consistently around 8 seconds, which led to a calculation of 2.72 km. It’s a simple calculation, everyone knows it. The time between the flash and the bang multiplied by the speed of sound, 340 m/s.
Then I got thinking that this isn’t, strictly speaking, true. The lightning and the thunder are created at the same time, they are the same phenomena. This means the light and sound both start travelling at the same time. So I came up with a more accurate formula to find the distance to an electrical storm by counting the time between the flash and the bang, accounting for the fact that the sound travels a certain distance before the light even reaches you. The distance, x, is then given by x=(cv/c-v)t*, where c is the speed of light, v the speed of sound and t the time between flash and bang.
It turned out to be pretty negligable. But still, for the purpose of accuracy I used this formula (and a slightly more accurate value for the speed of sound at sea level) and got a value of 2721 km. See, much better. Or at least as good as it will be using a value of the speed of sound at sea level, when the lightning is way up in the clouds.
A future exercise will be to account for the changing density of the atmosphere/density of the clouds/additional damping caused by rain, wind, etc.
Anyway, then I thought ‘if I keep watching, I can work out which direction the storm is in’. So I did. Then, naturally, I fired up Google maps and using my rough direction and distance, worked out where the storm was, to what I like to think is a reasonable accuracy.
Next time there’s a storm I am going to do the same, but then go to the storm and maybe take some pictures.
I’d best get some thick rubber soled boots.
* I really need to figure out how to get formulas in Wordpress.
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