Jul 20, 2007

What is Reality?

Interesting Wikipedia entry. Some excerpts:

1. "Some schools of buddhism hold that reality is something void of description, the formless which gives birth to all forms which are seen as mental illusions or maya. Buddhists hold that we can only point to things and discuss things which are not reality itself and that nothing can be said of reality which is true in any absolute sense ...... ."

2. "In psychiatry, reality, or rather the idea of being in touch with reality, is integral to the notion of schizophrenia, which has often been defined in part by reference to being "out of touch" with reality. The schizophrenic is said to have hallucinations and delusions which concern people and events that are not "real." However, there is controversy over what is considered "out of touch with reality," particularly due to the noticeable comparison of the process of forcibly institutionalising individuals for expressing their beliefs in society to reality enforcement."

3. "Certain ideas from physics, philosophy, sociology, literary criticism, and other fields shape various theories of reality. One such belief is that there simply and literally is no reality beyond the perceptions or beliefs we each have about reality. Such attitudes are summarized in the popular statement, "Perception is reality" or "Life is how you perceive reality" or "reality is what you can get away with" ...., and they indicate anti-realism, that is, the view that there is no objective reality, whether acknowledged explicitly or not."

4. "On a much broader and more subjective level, the private experiences, curiosity, inquiry, and selectivity involved in the personal interpretation of an event shapes reality as seen by one and only one individual and hence is called phenomenological .... From a phenomenological perspective, reality is that which is phenomenally real and unreality is nonexistent. Individual perception can be based upon an individual's personality, focus and style of attribution, causing him or her to see only what he or she wants to see or believes to be true."

5. "Berkeleyan idealism is the view, propounded by the Irish empiricist George Berkeley, that the objects of perception are actually ideas in the mind. On this view, one might be tempted to say that reality is a "mental construct"; this is not quite accurate, however, since on Berkeley's view perceptual ideas are created and coordinated by God. By the 20th century, views similar to Berkeley's were called phenomenalism. Phenomenalism differs from Berkeleyan idealism primarily in that Berkeley believed that minds, or souls, are not merely ideas nor made up of ideas, whereas varieties of phenomenalism, such as that advocated by Russell, tended to go farther to say that the mind itself is merely a collection of perceptions, memories, etc., and that there is no mind or soul over and above such mental events."

6. "Quantum mechanics (QM) has kept physicists and philosophers in debate on the nature of reality since its invention .... Primarily, one cannot measure the location and velocity of sub-atomic elements such as an electron precisely because the more one looks for the former the less accuracy one can achieve for the latter. This imprecision introduces an uncertainty into the overall state of the system and the necessity of a choice on the part of the one making the measurement, namely which aspect will he find accurately at the cost of the other. This decision on the part of the measurer has created no small problem for objectivists who insist that at its core reality is objectively present whether anyone notices or not. Several experiments such as the double slit and Bell's have confirmed that the simple act of observing does impact the system's state in a noticeable way; since the detector itself has to be changed to detect anything at all, there is necessarily a change in the observed particle because of quantum entanglement. But also the state of correlating particles which have not been measured appears to be affected.
Even the notion of cause and effect is brought into question in the quantum world where irreducible randomness cannot currently be avoided as a basic assumption. In theory large numbers of random quantum elements seen as a group from a very great distance can seem like cause and effect which is why our level of experience appears to function almost completely deterministically.

It has led some people to assume that there is no reality existing, independent of our own consciousness as observer."
I like the last part, heheh.

On a separate note, I've been investigating the unusual friendship between
David Bohm (the world-famous quantum physicist who contributed to the invention of the world's atomic bomb) and the Indian spiritual guru J Krishnamurti, who was believed by many to be an incarnation of the Maitreya Buddha.

A seemingly unlikely pair, but Bohm and Krishnamurti maintained their friendship over 25 years. Bohm and Krishnamurti exchanged
many ideas about the nature of reality. Specifically, the nature of space and time, and ... consciousness. Yeah, as one related package.

I'm still digesting, so I shall not comment too much. Still it is really not that unusual as you might think, for spiritual leaders to end up investigating quantum physics, and for quantum physicists to end up investigating religion. The Dalai Lama and Professor Fred Alan Wolf are two living examples.

8 comments:

Anonymous Coward said...

you're sense of reality is just a coherent illusion built by your brain. reality is as subjective as free will... http://bayblab.blogspot.com/2007/07/alien-hand-syndrome.html

great blog btw,
would you like to exchange links?

Anonymous said...

"Even the notion of cause and effect is brought into question in the quantum world where irreducible randomness cannot currently be avoided as a basic assumption".

I'm a graduate student doing research in the area of quantum information and I can assure you people from my field will tell you that line is bullshit.

Utama said...

Reality bites! ;)

just another physics student said...

Wang wrote:
Even the notion of cause and effect is brought into question in the quantum world where irreducible randomness cannot currently be avoided as a basic assumption.


I second anonymous reader's opinion (21 Jul, 2.43am).

However, to clarify the issue of indeterminacy and causality is more important than telling Wang he's spouting rubbish (cos so many people have tried to tell him, but he's still at it.)

1. Classical notion of determinacy.
Classically, the future path of a particle can be determined if the present position and momentum is known. This is the determinacy in classical physics.

2. Indeterminacy of the quantum world.
The position and momentum of a particle cannot be exactly known simultaneously. This means that, loosely speaking, not everything about how it is moving can be known, in principle. That is not due to imperfections in any measuring apparatus but it is built into nature. (Called Heisenberg's uncertainty principle).

3. Hence, if in the quantum world, the present state (position, momentum) of a particle cannot only be known to a limited degree of certainty, the future (path of the particle) can only be predicted to a limited degree.

4. This doesn't imply that causality is in question.

5. So Wang's statement above, in bold, where indeterminacy and possible violation of causality are mentioned in the same breath, may a misleading impression that indeterminacy leads to violation of cause-and-effect.

In my opinion, Wang should stop reproducing misleading statements about subjects for which he does not have deep understanding of. Else what all these mumbo jumbo merely does is to propagate misconceptions and pseudo-science.

Mr Wang Says So said...

As you say, I am reproducing excerpts (in this case, from Wikipedia).

If you think that any point is inaccurate, why don't you go to Wikipedia and have it corrected?
Then tell me about after that. This is after all what Wikipedia is all about (contributions, cross-checking etc by readers, I mean).

Since you mentioned "causality" as one of the areas where my excerpt has gone wrong, I might as well reproduce an excerpt from Wikipedia on "Causality (physics)" and you are most welcome to add your comments, if you please:

"Causality describes the relationship between causes and effects, and is fundamental to all natural science, especially physics. It is also studied from the perspectives of philosophy, computer science, and statistics.

In classical physics, it was assumed that all events are caused by earlier ones according to the known laws of nature, culminating in Pierre-Simon Laplace's claim that if the current state of the world were known with precision, it could be computed for any time in the future or the past.

According to classical physics, the cause simply had to precede its effect. In modern physics, the notion of causality had to be clarified.

The insights of the theory of special relativity confirmed the assumption of causality, but they made the meaning of the word "precede" observer-dependent. Consequently, the relativistic principle of causality says that the cause must precede its effect according to all inertial observers. This is equivalent to the statement that the cause and its effect are separated by a timelike interval, and the effect belongs to the future light cone of its cause. Equivalently, special relativity has shown that it is not only impossible to influence the past; it is also impossible to influence distant objects by signals that travel faster than the speed of light.

In the theory of general relativity, the concept of causality is generalized in the most straightforward way: the effect must belong to the future light cone of its cause, even if the spacetime is curved. New subtleties must be taken into account when we investigate causality in quantum mechanics and relativistic quantum field theory in particular. In quantum field theory, causality is closely related to the principle of locality. A careful analysis of the phenomena is needed, and the outcome slightly depends on the chosen interpretation of quantum mechanics: this is especially the case of the experiments involving quantum entanglement that require Bell's Theorem for their implications to be fully understood."

From there, we might as well as move on to the concept of RETROCAUSALITY - the idea that events in the future affect the events in the past:

"John Archibald Wheeler and Richard Feynman proposed a theory using retrocausality and a temporal form of destructive interference to explain the absence of a type of converging concentric wave suggested by certain solutions to Maxwell's equations. However, there has been no experimental observation of these "advanced waves", and it has been suggested that they may in fact simply be a different mathematical means to describe normal waves.

Feynman also employed retrocausality to propose a model of the positron by reinterpreting the negative-energy solutions of the Dirac equation. In this model, electrons moving backward in time1 would appear to possess a positive electric charge. Wheeler invoked this concept to explain the identical properties shared by all electrons, suggesting that "they are all the same electron" with a complex, self-intersecting worldline. Yoichiro Nambu later applied it to all production and annihilation of particle-antiparticle pairs, stating that "the eventual creation and annihilation of pairs that may occur now and then is no creation or annihilation, but only a change of direction of moving particles, from past to future, or from future to past." Although further understanding of antimatter has rendered this model largely obsolete,[20] it is still employed for conceptual purposes, such as in Feynman diagrams.

Current topics

Open topics in physics, especially involving the reconciliation of gravity with quantum physics, suggest that retrocausality may be possible under certain circumstances.

Closed timelike curves, in which the world line of an object returns to its origin, arise from some exact solutions to the Einstein field equation. Although closed timelike curves do not appear to exist under normal conditions, extreme environments of spacetime, such as a traversable wormhole or the region near certain cosmic strings, may allow their formation, implying a theoretical possibility of retrocausality. The exotic matter or topological defects required for the creation of those environments have not been observed. Furthermore, Stephen Hawking has suggested a mechanism which he described as the chronology protection conjecture that would destroy any such closed timelike curve before it could be used. These objections to the existence of closed timelike curves are not universally accepted, however.

Retrocausality has also been proposed as a mechanism to explain what Albert Einstein called "spooky action at a distance" occurring as a result of quantum entanglement. Although the prevailing scientific viewpoint is that the effects generated by quantum entanglement do not require any direct communication between the involved particles, Costa de Beauregard proposed an alternative theory. At an American Association for the Advancement of Science symposium, University of Washington physicist John Cramer presented the design for an experiment to test for backward causation in quantum entanglement, subsequently receiving some attention from the popular media. Although Cramer's experiment has never been performed as of 2006, retrocausality has also been proposed as an explanation[28] for the delayed choice quantum eraser.

The hypothetical superluminal particle called the tachyon, proposed in the context of the Bosonic string theory and certain other fields of high-energy physics, moves backward in time."

Anonymous said...

mr wang, you link for david bohm doesn't seem to be the right one.

Mr Wang Says So said...

Just received one of those unnecessarily snide & sarcastic comments from, well, you know, one of THOSE kinds of readers.

His comment won't be published because of the lack of courtesy. However, his comment also does contain a few valid substantive points as well as questions, so I invite him to resubmit his comment, minus the rudeness, and then it will be published.

Mr Wang Says So said...

Thank you, I have fixed the Dabid Bohm link on my main post.

Also the Wikipedia link on causality and physics (mentioned in my earlier post) should be this one.