Saturday, May 24, 2008

Stumbled upon this awesome link and I am so overwhelmed by the way the video is made and the way the info' is presented! The timing was quite right too, I had just finished reading the adventures of the physicist Richard Feynman and was so blown over by his personality and talent and had realised how we were not taught physics the way it should have been :( (I wonder if we can do any good to our DreamSchool kids :()
It's brilliant, never seemed to have liked any info' on the web so much. So thought of writing things that I understood from the clips (I haven't watched it completely... still need to watch the last hour out of the 3 hours but couldn't resist writing about it). Please watch it, it's worth every moment.

Newton's days (300 yrs ago) - He discovered that the force that makes an apple fall on to the ground is the same force that keeps the earth in its orbit as it revolves around the sun... and he called the force Gravity.

Einstein happened to prove that nothing can travel faster than light including gravity. And this meant that Newton was wrong. Because according to Newton, say if the sun disappeared due to some catastrophe, the earth (and other planets) would just move out of the orbit in a tangential direction immediately. Now with Einstein proving that light travels the fastest and that it takes 8 minutes for the light to reach earth from the sun, if the sun disappeared, how can earth move out of the orbit immediately as the effect of 'no gravity' would not even have reached the earth (it would take at least 8 minutes remember)!

So Newton was wrong in assuming that gravity was instantaneous, that it acts upon a body immediately! Einstein solved this by reasoning Gravity as wraps and curves in the fabric of space and time (you must see the video for this) and also so proved that gravity travels as fast as light and reaches the earth like waves through the fabric of time and space taking the same time as that of light. This is the general theory of relativity.

Now there is gravity, but there is also electromagnetism the force that bounces us back when we fall off a roof of a 40 storied building. If there were to be no electromagnetism, there would have been a hole formed in the earth due to the fall. And also this force is much stronger than gravity. It is the force due to repulsion of the electrons of the two bodies when they come closer.

Now we have a feeble force gravity and a strong force electromagnetism. Einstein's wanted to find an encompassing theory that combines the physical laws of these two forces as part of his dream to have a unified theory to explain the universe, a theory of everything that he couldn't achieve in his lifetime.

After this came the quantum mechanics which said that at the tiny scale of atoms and particles, everything is uncertain, the world is a game of chance! If you imagine yourself to be in a quantum cafe and order a blue coffee, it's not certain that you get a blue coffee, you might get a red coffee! But this uncertainty in the quantum world is at such a tiny scale that we don't realise it in the real world. Now this is a contradiction to the Einstein's theory of gravity which demands certainty.

Also along with electromagnetism there were the strong and weak nuclear forces at the atomic level... and the mainstream science had accepted the particles as points and successfully united the strong force, weak force and electromagnetism, they called it the standard model. And at this atomic/subatomic world of particles, the gravity which explains the large world of astronomy so well, never fit! it was the odd man out...

There were also a group of people who believed that the universe was made of tiny vibrating stands of energy called strings. And that the string theory can unite the conflicting set of laws (the laws that govern the larger objects like galaxies and the laws that govern the subatomic particles) with one master equation. It all happened when a young physicist discovered what appeared to be string like objects hidden beneath the abstract symbols of a 200 yr old equation. Though he thought he would be considered the next Einstein nothing like that happened as the mainstream science was busy unifying the nuclear forces and electromagnetism.

But some scientists continued to work on string theory trying to tame the unruly equations of the theory. There were anomalies like a particle with no mass and a particle that could travel faster than light etc. But when they thought of Gravity being that particle with no mass and of the other forces also as particles (these particles which are forces were called the messenger particles), things seem to fall in place. They could get an equation involving gravity too, which meant that they could explain how gravity worked at the subatomic level.

However the string theory demands more dimensions (eleven of them) than we know of (the 3 spacial dimension and one temporal). The idea here is explained in a very simple manner. If we look at cable that holds something, it looks like a line to us (from far) meaning we see just one dimension. But for an ant that is exploring that cable, from its point of view, another dimension comes into picture, the ant can move forward and backward along the length of the cable (dimension 1) and it also can move clock wise and anticlockwise along the circumference of the cable (dimension 2). So the spacial dimensions can come in 2 flavours, along the lengths (the ones we know of), along the circumference.

A German mathematician had already proposed the existence of an invisible extra spacial dimension as he needed a place for his electromagnetic ripples (like how gravity was explained as wraps and ripples over 3 spatial and 1 temporal dimensions) and Einstein believed in this German mathematician's proposal.

So even if there were to be more dimensions, how would these extra dimensions (of course they are not visible) look like? Scientists propose that at every single point in space, there is a circular ring whose circumference, only an ant that is billions of times smaller can explore. And the existence of these additional dimensions at every sinlge point in space is the heart of string theory!
And since it is all at that invisible scale, its difficult to prove it all by experiments but unless it is proven experimentally, it won't be science but philosophy and so the scientists are on their way to prove it all, good luck to them!

Source: The above info' is based on what is available at http://www.pbs.org/wgbh/nova/elegant/program_d.html

1 comment:

duvijan said...

Hi ash

I dont think it takes time for gravity to reach earth as with Light, gravity is ever present if it takes time to reach as with light, where would earth go. The core of sun pulls the core of the earth , this makes the sun and earth keep itself in equilibrium and similarily the core of earth pulls any object in its field. Electromagnetism and gravity are all forces raising from the core of itself , the assumption of gravity being weaker to Electromagnetic force is getting badly proven otherwise by current experiments.

Atom or universe or human being, core is core and at the core level ,the forces emanting manifest , the manifesting forces are called by different names. Inside an atom it is called Nuclear force , one level up outside the nuclear level inside the atomic level it is called as the Electromagnetism , ...until in the earth it is called as Gravity and if sun pulls the object it is called Levitation force.

Essentially force is the same , a human being has the same core. Well thats my model

Btw , how are you ?

-Vijay