my life is not very interesting

May 29

a subtle message

An alternative view on what actually happened to Harold Camping's may 21 prediction...

Apr 10

Agora que a polêmica de Belo Monte foi a nível internacional, retomei um velho projeto. Muitos números são jogados sobre o impacto ambiental ou o custo da Usina, e a resposta sempre costuma ser em como esse impacto é relativamente pequeno se comparado com outras formas de geração de energia. Mas quanto é esse impacto realmente? E como se compara a energia hidrelétrica com outras usinas? No meio dessa pesquisa descobri sobre muitas experências bacanas sendo realizadas no país, dos cataventos no Ceará a experimentação com cana em Juiz de Fora e Piracicaba. Alguns números são difíceis (quantas toneladas de cana são produzidos por hectares? E em álcool, isso é quanto? Isso é em MW, GW ou mWh?) então é possível que tenha errado em algumas conversões. A maior parte das fontes eu tirei de notícias publicadas em inauguração de usinas, e um pouco da wikipedia então recomendo a todos procurarem os seus próprios números.
Minha intenção e tornar você um jogador de SimCity, modo Brasil. Eu tenho a minha favorita, mas espero que não tenha ficado muito óbvio, pois prefiro que seja um infográfico neutro.

Mar 13

The Law of Truly Large Numbers

There are enemies of thinking everywhere: on TV, on twitter, on facebook. They are easily detectable and defeated, but most people never learnt about their existence. This is an attempt on diffusing them.
If you see a Logical Fallacy in the wild, do not hesitate: shoot it down as quickly as possible.

Reddit discussion

Mar 5

Einstein and the iceberg

Our universe is very counterintuitive. Take Relativity, for example: we know for a fact, that nothing can travel faster than the speed of light, and that it doesn't matter how fast we are travelling the speed of light is always the same, but how can that be?

To illustrate, let's imagine a story.

Imagine a Sailboat just crashed into an iceberg in the middle of a very dark night. There are only two lifeboats, and since no one agrees where is the closest land, the crew splits up, each in one direction.

Before they departed, they devised a system that they would use to let the other one know they were all right, and how far they were: after a the first ten minutes on the sea, each one of them would blow a whistle, to signal they were still alive and rowing.

Then they wait until they hear the signal and respond with another whistle.

And wait again, each time the wait being longer and longer...

So what happens here? Imagine there's somehow a super smart penguin on the iceberg and he can see both lifeboats, no matter how distant they are, or how dark the night is.

This is what he would see: First the ship crashes. The lifeboats leave.

The penguin sees both of them sending a signal simultaneously...

..but he will only hear them a little while later.

And the lifeboats will hear it later still, and respond back

The penguin hears both responses simultaneously, way before each lifeboat can.

And then finally, over a longer wait, each one of them hear the second signal, and sends a third one.

The end.

If we put these frames in order, with the distance between them proportional to the time it takes between them, and add few squiggly lines, that's what we get:

The green line represents the speed of the green lifeboat. The red line, the red lifeboat, the yellow line represents the speed it takes for he sound to travel around.

That's how the penguin perceives it, but would the captain on the first life boat agree? Remember, it's a windy night so it's quite probable that the iceberg itself is moving. Lets assume the captain is in a very bad mood (after all he just crashed) and believes himself to be rowing against the current, not moving at all. This is how he would perceive the same events:

What's the difference? We simply took the same data and did this transformation:

Here, we do not change anything on the X or Y line, and we simply changed which dot is in the center, changing all the speed along the way. In this view, for example, the sounds go faster going from left to rigth, same direction as the wind, than the reverse. In other words, time and distance is constant for all observers, speed is always relative.

This is the way we asumed for millenia that the universe works. But it's not.

For both captains, there is a way for them to detect where they are and how fast they are moving: they can either find land, or know the speed of the wind/current – knowing enables you to calculate the other. So a few smart scientists tried to do the same on our planet. Since they couldn't see anything on the universe that they were sure didn't move, they wanted to measure the speed of "wind", which they call Aether. And to measure that, all they had to do was to measure the differences in speed of light as we rotated around the sun.

But they couldn't. At first they thought they simply didn't have instruments precise enough, but for almost a century, smarter and smarter people spent their lives measuring zer change to increasingly accurate precision. Now we know that "aether" doesn't exist, that there is no universal "fixed ground" we can use as a reference, and that no matter how fast or where you are going, light never changes it's speed. How this can work?

Let's tell another story: Imagine both of our captains were able to reach land successfully, got back to their families and raised a very proud lines of marines. Captain Green's great-great-great-great-great son then becomes the captain of a spaceship that repeats a long honored family tradition and accidentally crashes in an asteroid.

They used the technique invented by their great-antecessors: each one of them launch their escape pod in opposing directions and after the first ten minutes of flight each one would send a radio signal to the other..

...wait for an answer...

..and then immediately respond with another message.

How would this events occur for a intelligent hyperdimensional alien living in the asteroid? For the sake of argument, let's assume both escape pods are traveling at half the speed of light.

For the Alien, the events would be identical to the ones with the ship and the iceberg: spaceship crashes in Ice Asteroid

Escape pods leave the ship travveling at 50% the speed of light, and then send a radio message to the other ship.

Alien on the asteroid receives both messages at the same time. Notice that althought we normally call the top speed anything can achieve the "Speed of light" this is a misnomer. It's also the speed of radio waves in a vacuum, speed of laser, the speed of neutrinos, and the speed of anything that has no mass. It's often called the "speed of information" because, if our alien was not hyper-dimensional, the radio waves arrive at the alien antennas at the same time that the image of the ships sending the signal arrive at the alien eyes.

After a while the first signal finally reaches the pods, and they send back the second signal. Notice that both messages arrive at the same time and are sent at the same time: There's no instant where there are two green signal or no red signal - this will be important later.

Which also reach the asteroid simultaneously, while the ships await the message..

Which finally arrives.

If we draw it on a graph, it will look identical to what the penguin on the iceberg experienced. But the same approach as before would not work from the Captain's point of view. In the boat example, the speed of sound changes with the wind and the speed of the listener, but we know from experience that light (and radio) doesn't behave that way. And if we put thi in consideration we get all sort os mismatches, like the Green pod receiving a reply from a message that red couldn't possibly have received..

The problem is that we are looking at the universe wrong. How wrong? 45º degree wrong:

Our universe is not a series of fixed spaces occurring one after the other like a flipbook: the universe is made of spacetime, and we live on a line running diagonal from it.

What we consider "right now", or all the events happening simultaneously, the thick diagonal line on the graph going from the bottom left to the top right. The observer always sits on the middle diagonal line, running from top left to bottom right. All information, light and massless particles (in the vacuum) travel straight down or straight right, any other thing must travel in between those speeds, going never up or left.

If we want to change our observer we cannot skew the graph as we did before – we have scale it while mantaining all the yellow lines in place.

This might mean that "right now" and distances are all relative to the observer.

If we change back to our own perspective this is what we get:

Is it getting clearer now? Let's see step by step, the same story, now from the Green Captains perspective:

Spaceship crashes on asteroid, escape pods are launched.

After ten minutes Green escape pod sends it's signal to Red escape pod. But since Red dot is experiencing time dilation – compared with Green's time frame, his clock has not ticked the tenth minute yet.

Green's message is halfway across to the asteroid and Red's clock finally reaches ten minutes. He send his message to green dot.

Although they sent messages at different times because of the time dilation, Red Pod is also experiencing space compression and it's a lot closer to the asteroid than Green is – from his perspective, that is.

After a while, Green receive Red's radio signal, and replies. But Green's first message is still halfway between the asteroid and the Receiver. Note that from the Green Pod perspective, both his messages still exist at the same time, but when we saw the universe from the asteroid point of view this never happened.

Red receives the first message from Green pod, when the second one is almost past the asteroid, just before Red sends his second reply, there exists a few minutes where there is no message from red anywhere between the ships - red is effectively completely silent for anyone on this neighborhood. From the point of view of the Alien on the asteroid, there was always a message from red being delivered.

The asteroid finally receives both messages at the same time, even though the Green's #2 was way closer to it a moment before. This means that from Green Pod's perspective, the Asteroid seems to be travelling at 0.5 c away from his messages, so the message takes longer to catchup. This is of course caused by time dilation and length contraction: as we have seen before, the Alien on the Asteroid didn't perceive either message coming any slower or faster than the exact speed of light.

Finally Red's second message arrives at Green's receiver.

From Green's calculations, his message is still halfway past the asteroid, and he almost double the distance from it than green is. If we were seeing this from the Red Escape Pod point of view, everything would be the exact opposite: when receive's Green's #2 message, it would calculate that it had received far before Red had. And from the Alien sitting on the asteroid, both had received at the same time.

So who received the message first? Green is not wrong – or at least he is not more or less wrong than the perspective of the asteroid or Red's. The order of events effectively changes, depending which direction and at what speed your spaceship is moving. In space, there is no common point of reference of what's happening now. But in the end it doesn't matter because the consequences are kept the same, and both messages always reach the destination.

If your head didn't melt in the middle of this article and you arrived at this end, the congratulations. There's s chance that you might be thinking: this makes absolutely no sense. How could you by walking left or right on your street, be changing if today is a tuesday or friday in Andromeda?

But years of experiments have shown that this is indeed how relativity works. And the sattelites that are bringing you this text right now, only stay afloat because they compensate for time and space relativistic effects.

The universe isn't always the way we find most comfortable or simple to understand. But we always try, nonetheless.

Feb 18

Lies, Damn lies and statistics

Business insider published this chart today, labeling it as a visualization of the collapse of the music industry, and how digital sales aren't doing enough to offset it.

The issue with this kind of stacking graph is that big changes on bottom layers always distort the top layers. Just changing the stack order, from bigger to smaller, gives us this chart:

For me this tells a very different story. Digital sales are almost reaching the turnover of the 70’s LP era (which no one ever says was a bad time for music), and the tape era of the 80’s. Looking this way, the “golden age” (at least for the CD business) of the 90’s seems more like an exception, an abberration, and this one, has clearly seen it’s end.