General Relativity VS Quantum Theory

[Stargazer]

The general relativity and quantum theory are both great theories. They describe the universe on different scales very accurately it seems. The problem is to form a theory that describes "everything" which would make it necessary to unite the two - although it doesn't seem possible. One, or both, will have to change.

[Tormod]

Originally Posted by TINNY

so how can euclidian geometry be simultaneously right and wrong? It has to be either one of the two. Refering to Bo, it is a matter of application and suitability.

Like Bo said: it has to do with dimensions. Euclid wrote his books in a 3D world with no knowledge of curved space. So for him, any triangle must have corners which make 180 degrees. This is still true, but only on a flat enough area (a piece of paper, say).

If you take a globe of the Earth and try to draw a perfect triangle on it you will see that it sums up to more than 180 degrees, becase of the curvature of the Earth.

So Euclid was not wrong. It's the same with Newton - he believed in action at a distance (instant action of gravity, say, between the Sun and the Earth) but Einstein proved this not to be the case. Yet we still use Newton's laws because generally they work, except when you need the laws of relativity.

It's about choosing the right tools for the job, basically.

[Tormod]

Originally Posted by alexander

Not to be rude or disrespectful or anything, and not to get off topic, we have a section to discuss this, so i'll be glad to discuss it there (if you'll start though pm me or something so i notice it, but i'll attend), just thought i'd say this: and so is the Bible, but that doesnt mean that the concept of religion is not entirely wrong... (and please dont mix it with beleif like most people)

We are talking about two different things: a science textbook which has stood the test of time, and a religious textbook which has evolved over time. Not everything Euclid said was right but it is okay to prove it wrong (although admittedly physics teachers of not-so-far-away-days were not exactly happy to accept this). With the bible things are a bit different...and like you say, this is not a discussion for this thread. Let's take it some other time.

[Stargazer]

A scientific theory or mathematical model can be "right" within its own limitations. In that way, Newton was "right," as Einstein was "right" too, only much more so.

[TINNY]

so when it involves QT and GR, how do we solve it? need a unification - GUT or somewhat?

[Bo]

yes, in cases like the big bang, or black holes, one needs buth quatum and gravitation effects. so we need a unification of the 2 theories

Bo

[TINNY]

has that been achieved?

[Stargazer]

No, and that's because it's not possible. One or both need to change first.

[TINNY]

why? are they mutually exclusive? or is there a fundamental law underlying the two?

[Stargazer]

As far as I understand, there have been some success in uniting the forces of the quantum mechanics, at least the electromagnetic and the weak force. However according to general relativity, gravity is not described as a force. I'm not sure if this is the only thing that makes it so different, but I suppose there is place for the graviton in the standard model, but it's never been detected. Also, the wave aspect has not been detected either. I am sure I'm wrong somewhere, but this is how I understand it.