BulgarianPride said:
newton did not discover gravity. Nobody discovered gravity. To this day nobody knows how gravity functions. We can model it, but we don't know what causes it. Scientist are looking for a particle called graviton, untill its found, God made mass to have gravity.
Gravity is one of the biggest mystery in science.
Errrr.....you're
sort of correct. To say that gravity and it's causes are a complete mystery is false. The thing that we struggle with, is a universal law for gravity. We understand how it works at the micro level and we understand how it works at the macro level, but these two systems are missing a common bond between them.
Within the last couple of months, there has been a HUGE deal made out of a paper studying a model called the
the Horava effect that some people are claiming will see the end of the debate, mainly because it alters Einstein's theory on spacetime as it splits space and time into two separate entities (kinda).
It's quite hard to explain without going into all of the maths and physics involved, but I'll have a try.
One of the big things that Einstein's
special theory of relativity states, is that time is experienced differently for things moving at different speeds. For example, there is a well known example of this called the twin paradox. Two brothers called Peter and Paul are twins who were born at the same moment on January 1st 1970. Peter is an astronaut whilst Paul is a mechanic. On January 1st, 2000 (their 30th birthday), Peter launches off into space in a spaceship on a mission to orbit the solar system whilst Paul goes to work normally in his garage. Now, this is the confusing bit, as Peter and his spaceship speed up to near the speed of light, they experience time slower than Paul does. As he has now done an orbit of the solar system and has now crashed down onto Earth, Peter will be looking at his clock and one year would have passed since he set off making him 31. However, when he meets Paul, he finds that as the Earth was travelling ,much slower than the spaceship, time has being experienced more and Paul is actually 51. From Paul's slow speed perspective, Peter has being gone for 21 years, whilst for the fast moving Peter, he has only being gone for 1 year.
This is what relativity is. The idea that as you speed up, the effects of time slow down for you and vice versa, thus any two things who are moving at the same speed will experience time in the same way. We call this "frames of reference". We are all currently moving at around the same speed on Earth, so we are all in the Earth's "frame of reference". Peter went out in his spaceship and travelled at a far, far greater speed thus Peter, his clock and everything else on that spaceship is in their own "frame of reference".
The reason why this realisation is such a huge step forward, is because we used to believe (thanks to Newton) that time was a universal thing just ticking away in the background. In Newton's world, 1 second passed here would mean that 1 second passed on Mars. A tick is a tick.
Einstein's theory of relativity successfully shown that time is actually another dimension which can also be changed just like the others. We live in a world of three dimensions; length, width, and height. We can change these things by exerting forces on an object, such as shaping Playdoh by pressing on it. Einstein shows that we could also change the fourth dimension of time by accelerating, and that it wasn't some static beast in the background but an ever living part of the universe around us. Remember this bit as it's important for later:
Einstein put space and time together as similar types of dimensions, which we usually refer to as spacetime. The scientific explanation for this, is that space and time are woven together, so acceleration makes things heavier, and makes them warp spacetime more. Just like putting a basketball in the middle of a trampoline (where the trampoline fabric is space, and a basketball is, say, a planet).
[bigimg]http://ideonexus.com/wp-content/uploads/2009/02/spacetimecurvature.png[/bigimg]
In the image above, the 'grid' is spacetime; space and time woven together.
Anyway, this leads to something called Lorentz symmetry. Lorentz symmetry is a law that states that any two objects (for example a clock and a person who are both in a spaceship) in the same frame of reference will observe the laws of physics in the same manner. To be more accurate, two objects in the same frame of reference in a non-accelerating or uniform motion, will observe the laws in the same way. It doesn't matter how quick you are going, as long as the other thing observing it is at the same speed as you, you will see them in the same way.
One of our problems, is that in our frame of reference (the Earth) we observe the laws of gravity in a different way in the planets and stars as we do in the sub-atomic world of protons and neutrons. If Lorenz Symmetry is correct (and there's huge evidence that it is) then this shouldn't happen. For example, one of the best known laws in physics and the simplest is that of the universal constant of
c.
c is the name given to the speed of light inside a vacuum (or space), and nothing can possibly travel faster than this. Every particle in the universe has what we call a limiting or maximum speed, and none of those may be higher than that speed of light. This is because light is a form of electromagnetic radiation, and the speed of at which this travels is 'set in stone' (inside a vacuum).
A good example could be of a proton. Let's say that a proton's maximum speed is higher than that of the speed of light (or electromagnetic radiation (EMR)). The proton would actually lose energy to the point whereby it would be impossible to go faster than EMR,
as observed by two objects in the same frame of reference.
Now, the sub-atomic or quantum world didn't match our expectations with the way that gravity works within it. Due to this, physicists have been twatting out ideas left, right and centre. Many believe it is because there is an external force at work that we haven't measured that we need to account for. This is where various pop physics theories come into play, such as Dark Matter, Dark Energy, String Theory, M-Theory, etc that have all offered (sometimes two bit) explanations of this and try to unify the actions of gravity normally and quantum gravity.
The problem, quite honestly, is that if you try to measure the force between two objects as a quantum graviton (in the same frame of reference), all of the calcuations quickly reach infinity, which is obviously wrong.
Horava has come up with a new idea which is currently gaining steam in the community. This idea states that space and time are NOT equal parts of one another in high energy environments such as the Big Bang, but 'weave together' once things settle down. I suppose it's like a bunch of needles in a haystack. At low energies (such as the normal magnetism created by the Earth), these objects are impossibly woven together yet in high energy environments (such as a room with a very strong magnetic ceiling) these things are completely separate. If you introduce a tiny bit of magnetism, you might see the needles move a bit.
Once you use Horava's model to calculate things, all of those nasty infinities go away and you are left with a perfectly normal graviton at the quantum level. This also means that Dark Matter and the like as redundant and no longer needed. This also explains why the Universe is speeding up, rather than slowing down. All of these little foibles in physics are about to go away, if this can be proven as correct.
Unfortunately, as Horava gravity is brand new, the model isn't perfect yet. Whilst it has been modelled against things that were attributed to Dark Energy, and has potentially solved the problem of the expanding Universe, and has potentially solved the problem of gravity acting different in the quantum world, it has been shown to not work in some cases. For example, all of the calculations which call the Sun a perfect sphere, Horava gravity produces perfect results, but if we call the Sun a non-perfect sphere (which it isn't) then the calculations are wildly different from what we observe.
As I have said, it's a brand new model that needs to be refined, but it is by far the most promising one for a hell of a long time.
So in conclusion, yes, gravity is a bit of a mystery at times, but to say we don't know how it works is wrong, and saying that the bits that we don't understand is God is incredibly frustrating and helps absolutely no-one.
If everybody thought like you, scientific progress would sotp tomorrow. I hope you remember that tonight as you sit in your house powered by electric, watching your TV beamed from a geo-synchronous satellite, while eating your tea cooked in the microwave.
