bhobba said:
Its inherent in the effective field theory approach to renomalisation.
To fully understand it you need to understand renormalisation a bit:
http://arxiv.org/pdf/hep-th/0212049.pdf
QFT in general, not just quantum gravity, but in general, has a dirty little secret. Infinities crop up all over the place eg the energy of the vacuum turns out to be infinite. Obviously its wrong. A careful analysis shows the cause is our theories, from dimensional analysis, often are missing a parameter. The most reasonable one is a cutoff at some energy. Low and behold when you put in the cutoff everything is finite. But what cutoff?
How did they determine what cut off to put in? And when then do they replace the infinite energies of the vacuum with, what energies of the vacuum?
Could it be the energies are infinite because 'time' is infinite? In that, matter/energy cannot be created or destroyed, only transformed, so energy can interact with itself infinitely?
Or is the vacuum values really the gravity values? That is to say the vacuum is the gravity field? And the reason it comes up as infinite energy, is because a mass in the vacuum or gravity field, can impart energy onto the gravity field and have energy imparted on it by the gravity field in a non exactable, there for, non finite way? Or in the gravity way, they don't know how many quanta per area of the gravity field, so they don't know the mass of the gravity particle, or its average density? Or the fact that the density of the gravity field, or vacuum, can be compressed and displaced, which gives it in the very least a non finite value, but a range of potential values?
The interesting thing about renormalisable theories is it turns out that parameters like charge, mass etc depend on the cutoff - these are called the bare quantities. But from measurements at low energy we know their value and can calculate what it would be at various cutoffs - this is called the renormalisation group flow. We don't know the cutoff, but regardless of what it is we can assign a value and hence compute anything we like.
Hm, so are you suggesting all the mass values may be wrong? Or we have narrowed them down to such a potentially certain range that if they were wrong they would be wrong by such a small amount? Or its just that the values for mass and such are self consistent, like the values relate to themselves as a self referential system, like a yard stick, the value system of mass is a created yardstick, that the particles qualities can be measured up against, but you are suggesting we may not know exactly how the yard stick relates to a fundamental way to reality?
The thing about gravity though is its not renormalisable - it turns out the number of parameters that need to be fixed is in a sense infinite so you can't do it. Drats. But it also turns out if you take the cutoff seriously its actually possible to construct a theory that is for all practical purposes the same as quantum gravity below the cutoff - and that theory allows things to be computed. This is the effective field theory approach to theories that are not renormalisable.
You seem to be stuck on this probability thing in QM.
I was only stuck on it, because I am just coming into an objective comprehension of the state of modern physics. I have been steadfast and skeptical and learning, and had heard mixed expressions, and with due diligence and the most careful thought performances which I know myself to have, I have found the most appropriate stance to take. I had heard a lot about the QM 'brand' of dazzling and spooky and bizarre and 'no one understands it' features, and have heard that people believe that QM is an exact reflection or perfect encapsulation of reality, and so from hearing that I was forced to consider their, and what appears to be your view. Though now after the past 2 years or so of armchairly learning physics in some free time, I am forced to take the side of Einstein and the materialist rationalist realists and say that QM is not a perfect map of reality as any ultimate Truth of Truth would be, but mans best yet tool of organization to perform different activities with the smallest known constituents of reality.
I have posted my view, and the view of a number of researchers into the foundations of QM, many times.
I appreciate that, truly.
Its simply the most reasonable extension of probability theory that allows continuous transformations between pure states. That's what is required if say a system can change to something in one second, then it should in the process of that change to something in half a second.
I have no problem with models and theories and equations. I only have a problem with someone claiming that a model, theory or equation is Truth with the most capital T, when arguments can be made for a more, ironically, probable interpretation of those statements. (Truth in this circumstance, and all really, referring to the difficult/impossible notion to challenge that 'Reality = Reality', and that that is what Truth is, and if your model and theory and equation is not an equal part of Reality = Reality, then the model or theory or equation is not Truth, not the essence of reality.
Certainly anyway we discover these things will be symbolic. I can say, a worm bit a red apple that was laying in a field. And you can imagine those things in your head clearly. These words are symbols, the images in your head are symbols, but to a pretty high degree they correlate to something, greatly arguably to exist and be real components of reality. An apple exists, we may not know everything there is to know about an apple, but 'something is there', that 'something' whatever it is, equals itself. Reality is tautological.
The problem I have with QM and the probabilities in it, is they are trying to make reality their equations. They are saying, 'we can only use probabilities to do experiments and make predictions, that means the universe can only use probabilities to exist, therefore our equation, with its probabilities, is equal to the universe, the equations have probabilities, so the universe most be made of probabilities'.
Now one of the most beautiful and startling things about the universe, is the human mind, because there is a case that does appear to defy determinism truly. Its severely complex, and I suppose part of the reason is because it creates a fake reality within it! That is composed of its own symbolic language and logic, which it can compute together, so to other observers, the unique nature of this symbolic mind language, is unpredictable. But however, not that I believe in human determinism, I believe in it to an extent of course (you must eat to live, you must have been born by your parents to live, its determined that your parents must be born before you) but I also believe in free will. I don't believe that the fundamental constituents of the universe have free will and for them to have probability they must. And in this case, just because we can not decipher the determinacy of fundamental constituents, doesn't mean they are not determined by reasons. QM and the probability interpretation, suggests that everything happens for no reason, in a physical sense of course, that is to say, I drop an ice cube and it breaks on the floor, the ice cube fell for a physical reason, the ice cube broke for a physical reason, the ice cube froze in the first place for a physical reason. Probability interpretation is saying, like an ancient man who didnt know how ice froze, like an ancient man that didnt know why physically ice fell, like an ancient man that didnt know how or why ice broke when it fell to the floor, that because he doesn't know these things, there must be know reason. Because you don't know a particles location and momentum at the same time, it must not have them. Because your equations can not know exact things about particles you must utilize probabilities, therefore the universe must utilize probabilities.
nature is just - well nature - it is what it is.
Now that I can agree with!
