Hello everyone! I wanted to thank this website. It brought my sanity back! I'm not english so I'm sorry if I cannot speak correctly in every way but I'll try my best. Religion and more in general, woo woo have always worried and scared me; i've always had only one "faith": trust in my reason, in the beauty of the world, and the respect of life. But about a year ago i got into the woowoo thing for some months, the quantum woo woo and stuff because i thought it could be the antidote to nihilism or pessimism (not in me, but in general). I was sooo wrong. Trust in mankind, in reason, in freedom and in beauty are the best way of thinking for me, and you guys are responsiblie for having brought these values back to me. Searching for evidence, self-reliance (not without rational foundation), knowing the worth of little things and appreciating the immensity of Nature are to me now the candles in the dark of fear and superstition, the paths traced by man for man, through science and humanism. So thanks again. I have a little question for the scientific experts here. I'm a law student (so science isn't really my field) but I'm just starting to appreciate the wonders of real science, but.. Can someone explain to me in a simple and clear (rational) way what quantum mechanics REALLY is, what is the "observer effect", and the uncertainty principle? Does these studies imply or make valuable mystical or religious views of life or the involvement of human conscioussness in reality? From what I read they do not, but I find such topics, difficult to understand. So I'm asking all you skeptics and rationalists (who are involved in science and thinkin in a good way). Thanks again everyone! — Unsigned, by: Gianga23 / talk / contribs
- What you read is correct. Quantum mechanics is a set of theories that purport to explain how interactions occur on incredibly small scales (and it does a damn good job). However, as a scientific theory, it makes no implications about any views on life, mystics, religion, consciousness, etc., as those implications would not be testable or falsifiable (thus, no real physical theory could include them).
- The observer effect is sort of a hand-waving way to explain the effects of observation/measurement in quantum mechanics. Effectively, a quantum state can be in what's called a superposition (think Schrodinger's cat, which is both alive and dead until observed). Upon observing (measuring) the state, it collapses into a definite state (e.g. the cat becomes either alive or dead, not both any longer). This confuses quantum woo-meisters and sets up the consciousness debate because they think that this makes human observation special. It's important to note that any measurement, human or not, will disturb such a state. It's also worth noting that in some interpretations of quantum mechanics, quantum states are taken to represent the completeness of our knowledge about some physical state (instead of the physical state itself). Thus, a superposition state would simply imply that we don't know what the physical state is with complete certainty (e.g. we just don't know if the cat is alive or dead). Upon measuring, the state "collapses", and our knowledge becomes complete. In this picture, the observer effect becomes completely trivial and not at all mysterious.
- As for the uncertainty principles (since there are more than one), any two non-commuting operators (mathematical objects representing quantum measurements) will have some uncertainty in their measurement. The simple explanation for this is as follows. In classical mechanics, if we know the position and momentum of an object, we know everything about its trajectory. We can map out where it will go, and if we know what forces are acting on the object, we can also update our predictions to account for that as time goes on. Position and momentum are thus known as canonical variables. In quantum mechanics, position and momentum are now canonical operators, and they do not commute.
- The uncertainty principle stipulates that there is a lower bound on the certainty of our measurements in both operators. Thus, if we measure a quantum object's position with 100% certainty, its position state collapses into a point (thus it exists at a single point in space). However, the position and momentum states are related due to this canonical relation, so taking this position measurement also "collapses" the object's momentum state into a plane wave. In other words, its momentum gets smeared over all possible values. The same is true in reverse. If we measure the object's momentum with 100% certainty, its momentum state collapses into a point, and its position state smears over all space (thus, we know the object's momentum, but there's an equal probability that it could be anywhere in the space we're looking at).
- I hope that helps, and if you have any other questions, feel free to ask. - GrantC (talk) 16:03, 31 December 2013 (UTC)
Thank you so much for the explanation and sorry for the huge delay in answering,
I think I've understood the uncertainty principles pretty well, but as for the observer effect, I don't get the meaning of "quantum state", "observing" and "collapses".. And you wrote "some interpretations of quantum mechanics".. Is there one more accurate or scientific than the other?
The picture I get is more or less this (for a layman like myself): human consciousness doesn't play any role in modifying or even more creating any reality out there, when you have to measure a tiny object to which quantum physics applies, there are some equations that can make you calculate the probabilty of the position of the object...observing simply means "ah look now we know where the thing is", collapsing means "the thing is here".
So my question is simple and yet maybe trivial... Event though scientific theories as you've said (I don't wholly agree with you on this) make no implication of views on life and so on (I think the behavioural and physical study do make some deductions from how the world seems to us, at least, seen through the scientific method lens), can we actually say that serious and verifiable science falsies (I'm getting a little further here maybe) or makes very very improbable these three theses (or at least doens't confirm them)? "Atoms are conscious" "The universe is conscious" "Human consciousness changes or create external things just by itself."
- I'll try to answer as best I can. The definition of a "quantum state" actually depends on your interpretation (as does the definition of "collapse"). As for which interpretation is "more correct", that's more difficult. These interpretations, in and of themselves, aren't testable. For example, in one interpretation, you can view the quantum state as a literal physical state. In other words, the quantum state contains all information about what an object is and what its properties are. There exists another interpretation in which quantum states are just states of knowledge. In other words, the quantum state represents how much we know about an object. If you want some other examples, two common interpretations are the Copenhagen interpretation and the many worlds hypothesis, so feel free to poke around Wikipedia for those. Under those definitions, it's really not possible to say which one is more accurate. The underlying science says nothing about that.
- You're correct that consciousness plays no role in this, and the picture you have is good enough. In most interpretations, an "observation" is just any measurement that causes a state to collapse (note that this isn't quite correct; there are measurements that don't collapse states - weak measurement - but that's a very complex subject). In terms of quantum mechanics, a beam of light or a stream of particles hitting a detector is an observation. The same is true for a magnetic field that collapses a spin state. There's no real need for any consciousness to be involved.
- So to answer your actual question, you really have to define what consciousness is. If you believe a quantum state is actually a physical state of an object, then collapse does contain a bit of "magic", in that it's a bit harder to understand what it means. If you believe a quantum state is just a state of knowledge, then collapse is no longer mysterious, and these observations are more like firming up our knowledge about some object's properties. Do either picture suggest that there's any consciousness behind this? No, I don't think so. It's much like the principle of least action. Just because you can use this principle to predict the exact path of a classical particle, that doesn't mean the particle is actively choosing that path.
- It's also worth considering that at the end of the day, your questions aren't falsifiable. However, it's worth noting that at the end of the day, all objects in the universe follow a set of rules (the laws of physics), and these rules aren't broken. If atoms are conscious, then they're all following the exact same rules by choice, which is impressive, given that there's no way they could all be in communication with each other. If the universe is conscious, well we can't exactly go study that, but science also doesn't do anything to support or confirm it. As to your last point, no, there's no evidence at all that human consciousness is special or can change/create things. - Grant (talk) 14:35, 9 May 2014 (UTC)
Okok, thanks again. One last question: what's the entanglement? And does it provide a proof for an allaged holistic interpretation of the universe? I've read that a change to one particle is istantenously made to another, but at the same time that energy and information cannot be transferred faster than the speed of light; and if you encode information in a system it destroys the entanglement...but really, what does it mean? Is relativity still true and we live in a universe made of discrete particles that can get in a contact locally, or what?Gianga23 (talk) 15:09, 25 May 2014 (UTC)
- Entanglement is a complicated problem, but no, there's no violation of relativity involved. The thing is that no information is transferred when this "spooky action at a distance" (as Einstein called it) happens. Any schemes that involve using entanglement to transfer information all require some amount of information to be sent classically (as you say, encoding information destroys the entanglement), so there's never any violation of the speed of light. As for locality, well... That's more complicated. Theoretically, there's no limit to the distance over which two particles can be entangled. In reality, however, entanglement tends to be a fragile thing, so the entire universe isn't really entangled or anything like that. Current theory suggests, however, that locality isn't necessarily a fundamental rule. More and more experimental tests are stripping away any loopholes that might exist (Zeilinger's being the latest), and it seems more and more likely that entanglement is a non-local phenomenon.