Quote:Being able to determine the future does NOT imply that the past can be determined. There would be infinite possible pasts that correspond to any given future. It is possible to make probabilistic guesses about the past, and this is of course what a lot of scientists are trying to figure out (geologists, astronomers, etc). The only difference is that in your thought experiment we possess all knowable information and in real life we must make measurements to gain information.
Actually that's not quite true. If you can know everything about the universe right now and can predict what will happen, if determinism is right that is, then you can theoretically work backwards and determine the past.
For example, if an isolated system merely contains two marbles:
- If an event occurs where Marble A, starting out at Position(initial) A, collides with Marble B, in Position(initial) B, with a certain momentum at an Angle Theta, and Marble A ends up in Position(final) A and Marble B ends up in Position(final) B,
- Assuming that you can know and do know every property within this system and assuming no outside systems interact with this system,
- Then it is possible for you to know what will happen
-- Also, theoretically you can also know, if you know everything within that system when you are at Time(final), where Marble(A) and Marble(B) starts out, what their Momentum(initial)s are, the Angle Theta, Time(initial), etc. Thus you would be able to predict the past. It is actually common for a Physics question to ask something similar to this where you are ask to determine the initial momentum or position of a certain object.
My initial problem in my post, is also that of a beginning. If there is an absolute beginning, then it must follow that a cause of this beginning is the effect itself. This seems to contradict the premise of determinism.
Quote:If you believe in determinism, then there is only one possible future, and nothing at all can influence it in the slightest bit because every decision you make, and all the associated chemical reactions in your brain, could be predicted.
Yes, but there is a problem in the hypothesis of knowing a future in that a person knowing a certain "future" may decide to do something otherwise. In that case the "future" he or she sees, will be altered and will not be the actual future, which would question how much we can really know of the future.
Quote:Answered already above.
It seemed like a similar question, but it is different than the last question. My question for this was that if the "knower" is within a system, and since, based on our information of how we know empirically, then the "knower" would have to interact physically with other parts of the system in order to "know" and thus something within the system has already changed.
Quote:Yes, all of modern physics is based on the underlying principle that the universe is not deterministic.
However, I consider it important to understand that the Uncertainty Principle, like ALL scientific theories, is simply an idea that somebody thought of which has been shown to make accurate predictions of the physical world.
In this case, the uncertainty principle represents the fact that scientists have observed literally random or uncertain behavior.
However, just because it appears random does not necessarily make it so, and there are still scientists who (like Einstein) believe that behind the uncertainty principle lie more simple, deterministic laws that merely cause things to appear random at a higher level.
There are some interesting effects such as entanglement which show that although two individual particles may both appear to be acting randomly when considered separately, the two of them are dependent on each other. I consider this to be evidence for some lower level determinism but that's a radical, personal opinion.
It is most likely that we will never know, truly, how the universe works at it's most basic level because it is like a black box paradigm. There are infinite possible ways to build a clock, and there are only so many tests you can do on a clock without opening it up to see how it works. We can only "open up" particles so far before the very instruments that we are using to make measurements start to dramatically change what we are measuring. This is actually how the uncertainty principle was conceived in the first place.
I agree that quantum physics is incomplete. However, the uncertainty principle is showing the limit of experimentation. It shows that if you are experimenting a certain velocity of an electron at a certain time, you will not be able to measure its momentum at that time either because the momentum has been changed when you measure it, and/or because you cannot rewind time and preserve the data of the velocity with you. There are also many paradoxes to time travel in this case.
Also, think of how we record our data. We are using photons, or other particles. Also think of what it means to record data, it means that something has to interact with something.
Quote:The foundation of determinism as I understand it, is everything is a middle link in a chain-link fence of causes that continues ever forward. The ability to predict it or lack thereof is neither here nor there.
No, one of the premises or suggestion of determinism is that you can theoretically predict the future.
Quote:Not if the 'cause' originated outside what we understand to be the universe.
That's an interesting statement, but it is based on an assumption. Also if the "knower" can know this force outside the universe, then you have the same problem.
Quote:Yes, which is a good argument for not being able to predict the future.
Yes, agree completely with your statement here.
