Talk:Causal sets

Geodesics

Shouldn't the definition of geodesic, currently "The length of the chain, n, is maximal over all chains from x\, to y\,." be "minimal" instead?

It depends on the signature you adopt for Minkowski Space - if [1, -1, -1, -1] then maximal corresponds to not swanning about in space. The causal property prevents you swanning about in time.

75.67.249.169 (talk) 23:40, 23 October 2012 (UTC)

We're not talking about the length in Minkowski space, n is simply the number of links in the chain. What does the metric have to do with it? — Preceding unsigned comment added by 130.216.209.138 (talk) 03:01, 28 June 2013 (UTC)

No. Maximal is correct. The shortest chains will generically have length 3, and will traverse a spatial distance comparable to the temporal separation between x and y. DavidRideout (talk) 23:15, 14 August 2018 (UTC)

Relevant?

Russell and Whitehead's theory of space-time, called "eventism," reduces to the theory of causal sets when it is constrained to finite sets of events. Causal sets form relative frequencies, which leads directly to the definition of mass-energy in accord with Planck's E=hf. Each "causal link" is then a quantum. Fundamental particles, including the electron, neutrino, proton and neutron, have been modeled by Carey R. Carlson as simple causal sets.

This paragraph was moved from the main causal set article because it is unclear (e.g. "Each causal link is then a quantum"??), unsourced (e.g Where's a reference for Russell and Whitehead's eventism theory? Carey R. Carlson's work?) and contains incorrect statements (e.g. the proton and neutron are not fundamental particles - see quarks). StevenJohnston (talk) 13:46, 22 February 2008 (UTC)

To clarify, there are no fundamental particles at all when physics is reduced to causal sets. There are only the elements (relata) and the pairing relations (causal links.) This reduced ontology is sufficient to construct the nuclei and the electron clouds of the atoms as causal sets, as well as the neutrino modes of propagation. I self-published my initial findings as "A Theory of Everything for Physics" in 2005, without having heard about "causal sets." I have an article coming out soon in a collection edited by David Skrbina, which will subject my work to its first peer review. David's book is "Mind That Abides: Panpsychism in the New Millenium." My article is "Finite Eventism." Search the phrase "finite eventism" for links to David's book and my posted writings, including "The Structure of Quarks." 71.37.249.99 (talk) 16:51, 3 November 2008 (UTC)

I've posted the theory and its diagrams on a site called "viXra." Here is a link to the paper, and a copy of its abstract: http://vixra.org/abs/1006.0070 "Causal Set Theory and the Origin of Mass-ratio" Quantum theory is reconstructed using standalone causal sets. The frequency ratios inherent in causal sets are used to define energy-ratios, implicating the causal link as the quantum of action. Space-time and its particle-like sequences are then constructed from causal links. A 4-D time-lattice pattern is defined and used to model neutrinos and electron clouds, which together constitute our 4-D manifold. A 6-D time-lattice is used to model the nucleons. The integration of the nucleus with its electron cloud allows calculation of the mass-ratio of the proton (or the neutron) with respect to the electron. Arrow diagrams, along with several ball-and-stick models, are used to streamline the presentation. -- Carey 71.210.164.16 (talk) 18:57, 6 July 2010 (UTC)

Partial orders are REFLEXIVE (not irreflexive)

On http://www.phy.olemiss.edu/~luca/Topics/c/causal_sets.html you find the following definition:

Causal set: A (locally) finite partially ordered set, in which the order is causally interpreted.

See also the nlab entry http://ncatlab.org/nlab/show/causet. HansBlatter (talk) 11:39, 21 October 2009 (UTC)

They can be either reflexive or irreflexive, it does not matter. Each convention is more convenient in different contexts. Though if you discard irreflexivity you must impose acyclicity. 129.97.120.253 (talk) 14:54, 8 November 2010 (UTC)

Length of Chains

There is a problem with the definition of length of chains. x0<x1 is length 1, if it is correct that the length is the number of relations in the chain, but according to the given enumeration (x0 ...x(n-1)) and the statement that the length is the value of n, we get a length of 2.!

75.67.249.169 (talk) 12:30, 23 October 2012 (UTC)

No, the definition is consistent, in your example (that is, x0<x1) n is 1.Paolo Lipparini (talk) 10:15, 10 September 2014 (UTC)

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Verifiability of Kastner Article?

I don't want to say anything definitive, because it's possible I haven't fully understood the Kastner article, but I can't help but question not only the relevance, but also the validity of what is being proposed. Not only has the article gone all but unnoticed by anybody working on causal sets (and the physics community at large, for that matter), but the paper appears to make very little contribution to the field. It is explicitly not peer reviewed.

The arguments are only sparsely reinforced by mathematical formalism and some phrases that are used seem to be quite frankly fictitious. The premise of the article is a hotly debated topic elsewhere with all but exactly two persons standing behind it, only one of whom holds physics credentials. The contents of the paper offer nothing that may be used by researchers to advance the study of causal set dynamics, making the claims borderline unfalsifiable. On several occasions, the author redefines or blatantly ignores axioms that are essential to the theory in the absence of an alternative justification and never indicates that they are doing so.

Had it not been for the preceding issues, then the author's questionable credentials would be an inappropriate subject matter, but unfortunately they are.

Developing a quantum dynamics for causal set theory has been an issue for decades, and there are many physicists hard at work trying to develop them. It is frankly disrespectful towards these researchers to make the bombastic claim that such a flippant article "can provide the quantum dynamics for the causal set." It is unthinkable that this section would include Kastner's article while making no mention of the work of Benincasa, Dowker, Surya, and Glaser in this direction.

I am adding tags for the time being, and unless the theory can be attested to by someone other than Kastner, it should be removed from this article. At the very least, it constitutes a no original research issue.

AndersLeo (talk) 17:46, 4 June 2018 (UTC)

Einstein Manifold

How about Einstein manifold and Causal sets? Is there any preference/prevalence over the manifold of Einstein-Cartan theory? Or is Einstein-Cartan theory also compatible with Causal sets? --Ernsts (talk) 22:43, 6 June 2022 (UTC)

Argumentative basis missing from the article

In the first paragraph, it is stated that the core idea is that “spacetime is fundamentally discrete”.
But the logical basis for that cannot be found anywhere in the article. No observations, and no line of reasoning from them to the statement. It is just treated like an axiom/paradigm/dogma.
So no connection to reality and no indication of usefulness of any kind. In other words: About as scientific as religion.
Yet it is somehow grouped with scientific theories. Instead of fiction/fantasy.
I question why this is even an article. Given its uselessness, even for entertainment reasons.
Can we add an argumentative basis or remove the article? Wikipedia is no place for any arbitrary crazy person’s hallucination.
— 2A0A:A546:59D2:1:8BA6:3F64:32C2:F853 (talk) 13:38, 11 November 2024 (UTC)

Wolfram

No mention of the similarities to Wolfram's new "Class Model To Represent Fundamental Physics" even considering there seems to be some collboration between Jonathan Gorard and this group who has published some new papers recently? According to Hossenfelder and others, these are very similar 2600:1700:5BD0:4400:9D41:6822:E840:1BB4 (talk) 14:38, 26 November 2024 (UTC)