Monday, August 22, 2011

How speaking works

Exactly how does speaking work? What happens in human brain? Surely it requires a lot of processing power? To be able to speak meaningful sentences out fluently, one must be able to plan what to say next, organise the words of the current sentence into correct order and pronounce the current word correctly. And speaking can not take your whole attention, you must be able to for instance walk at the same time.


According to studies, following parts are most active when we speak:


  • auditory cortex 
  • lateral sulcus (producing spoken language)
  • temporal lobe (meaning of heard words)
  • Wernicke's area (language comprehension)
  • Broca's area (speech generation)
  • motor region
What does this mean? How do these areas work together to form speach? I assume it all goes like this: in the brain there are multiple processes. Lateral sulcus is working - together with memory - as a preparatory process: it works in advance and prepares the abstract ideas that we are about to speak out. These ideas are not yet at this stage connected to words. The next process, The next process works in temporal lobe, and it connects abstract ideas with words. This must be done together with language comprehension process, which is done to form correctly formed sentences. The next phase is forming speech mechanically, which is done in motoric area, controlled by Broca's area, where speeck is actually produced.

These processes all work in parallel, without planning the whole sentence beforehand. When you are speaking a certain word of a sentence, you will probably know what you are going to say in that sentence in abstract level, but you don't necessarily yet what the words will be, and in what order they will come, until they do.

Let us look at some everyday examples, for how they fit to the model we have created:

Synonyms.

Sometimes it happens that when one speaks, there are two equal synonyms to choose from, but unable to choose quickly enough, the spoken word will come out as a funny combination of the two synonyms. The speaking processes feedback mechanism will quickly detect this error and the speaker will correct the mistake. But what happened? An easyexplanation is that the word-choosing process was not quite finished when it had to output the net word to the speech generation process. This caused the word to change in the middle of being pronounced.

Lost for words.

The same applies when a suitable word can not be found even if one has the idea ready. The database query just does not seem to produce any results, or the results are in wrong language. In this situation the speaker will either use some fill words to buy some time for extended database search - or return the control to the preparatory process and re-form the sentence so that the specific word would not be needed.

Blackout.

This has happened to me, and I don't think I'm the only one. When completing a sentence,  there is no next sentence available in queue, or the next sentence does not seem to have anything to do with the one you just finished. I can imagine this as a synchronisation problem in Lateral sulcus: it is working too fast. the human communication transmission method has a very limited bandwidth, and the speed of thought must keep in sync in order for the opponent to understand the speech. I assume the blackout is a result of the monitor, which is observing our own speech and providing feedback to the processes of what our own speech sounds like, real-time. If the lateral sulcus notes that the speech in the feedback channel does not have anything to do with the idea or sentence currently being prepared, the process will halt.


A great article: Connections between thought and language


Wednesday, August 3, 2011

Famous two space ships problem

Following is an often-used example to illustrate similarities in gravity and acceleration.

There are two space ships. One of them is standing still on earth, and the other is in space, thrusting with constant force and therefore accelerating exactly at 9.807 m/s2, which happens to be exactly the same as the gravity constant on earth. A person is standing in both of the rockets, but they were brought to the ship in a way that they do now know which ship it is. Assuming the passenger cabins are completely isolated from the environment (no windows, sound protected), would there be any means for the passenger to find out somehow which ship it is?


Let's try some classic Newton physics. Jumping around or throwihg around objects will feel exactly the same on both ships. No help there.

If classical physics does not help, what about relational physics then? Let's try to measure speed of light for instance. Maybe the moving ship will capture rays of light differently than the ship that stays still? Unfortunately not. Speed of light is constant and does not depend on the speed of the observer. Besides earth is also moving, very fast. Our galaxy is not staying still.

Butwhat happens when the accelerating ship starts to reach the speed of light? The Lorenz formula below can be used to calculate moving objects' relational mass.

Assume that after a while of thrusting, the velocity is 95% of light speed. The ship mass has become over 3 times its original mass. Maybe all the passenger needs to do is to weight some known object (like himself) regularly and if the weight increases, he will know that the ship is moving very fast. But no, even in the moving ship, the weight will measure the same. The inertial mass has no meaning for the moving object itself - it is a relational mass. It only has meaning for objects that observe its speed. But if the ship would crash into another ship with its full speed, it would feel its increased mass...

Only the fuel reserve set the limits how long the ship could accelerate. There is no other limit. And no matter how close to the speed of light the ship reaches, still, there is no way for the passenger to notice any difference.


Now, if you made it this far, here's something different to think. In the first ship, which force creates the push towards the floor? Yes, gravity. Generated by the planet. There is a field, or little particles if you will, that penetrate even the ship's thick walls that causes all atoms to draw themselves towards eachother. This appears as gravity.

What about the other case? What causes the push towards the floor in the other ship? There are no gravitational sources (at least none significant so we can ignore that) We know that the ship is accelerating, but how do the objects inside the ship know that? What is the coordinate system tied into? it could as well be tied into the ship, in which case the objects in the ship would be floating in zero gravity. But it is not. It seems like the coordinate system system was tied into a point outside of the ship - in the universe itself. So what is the zero point of the coordinate system? What creates this coordinate system, and what creates the force?

Answer to this is the Higgs field. The coordinate system is tied to the average center point of the universe, and the Higgs field itself causes all objects to resist sudden movements. This is what we experience as "mass".

Best wishes for LHC folks at CERN. Hope you catch the Higgs Boson soon! :-)