Hoi-Lai Yu (7/8/102) said: Hi, Guys you can submit your thoughts and notes by just typing. Cheers, Hoi-Lai

CShan (7/9/102) said: Web bookmark from Darwin.... http://citeseer.nj.nec.com/260969.html http://citeseer.nj.nec.com/sasaki99evolving.html it is a paper on Life and Evolution in Computers ... something similar to what we have been trying to do with linux, http://citeseer.nj.nec.com/mitchell98complexsystems.html http://citeseer.nj.nec.com/105590.html we may find this interesting too.... debate about whether dynamics or structure is more important in cognition.

Anonymous user using at (7/16/102) said: Hi, I get a "Wiki" program, it is free forum like program. Actually, it is more than a forum, because you can modify any existing page. I have installed it in my UW web space. I will send you guys email for the user name and password.

Hoi-Lai Yu (7/19/102) said: Strominger\cite{Strominger} had observed an intriguing feature of the dS/CFT correspondence when identifying the time evolution in the bulk of the universe with scale transformations in the boundary. In flat Robertson-Walker coordinates the \ds\ metric is \begin{equation} ds^2=-dt^2+e^{2Ht}d\vec{x^2}, \end{equation} where $H$ is the Hubble constant. This geometry is isometric under the modified time translations \begin{equation} t \rightarrow t+\lambda,~~~~~ \vec{x} \rightarrow e^{-\lambda H} \vec{x}, \label{RGE} \end{equation} whose generator we will refer to as ${\cal H}$. From the first term in Eq.(\ref{RGE}) we see that ${\cal H}$ generates time evolution in the bulk gravity theory, while from the second term we see that it generates scale transformations in the boundary theory. Furthermore late times in the bulk correspond to the UV (ultraviolet) of the boundary field theory, while early times correspond to the IR (infrared). On another hand, our universe is well-approximated by a geometry of the Robertson-Walker form \begin{equation} ds^2=-dt^2+R^2(t)d \vec{x^2}, \end{equation} where at early times \begin{equation} t\to -\infty,~~~~~{\dot R \over R}\to H_i, \end{equation} while at late times \begin{equation} t\to \infty,~~~~~{\dot R \over R}\to H_f . \end{equation} $H_i$ here is the inflationary era Hubble constant, typically taken to be of order $10^{24}$ cm$^{-1}$. $H_f$ is the final value of the Hubble constant which recent observations indicate may be of order $10^{-28}$ cm$^{-1}$. At intermediate times $R(t)$ corresponds to standard big bang cosmology. For such a function $R(t)$, the universe has no isometry of the form Eq.(\ref{RGE}), and there would be no reason to expect a dual representation of the bulk gravity theory as a boundary conformal field theory. The absence of a bulk isometry had leaded Strominger to conjecture that this is to correspond to a boundary field theory which is not conformally invariant. Bulk time evolution is dual to RG (renormalization group) flow in the boundary field theory. Since the isometry Eq.(\ref{RGE}) is recovered for $t\to \pm \infty$, the RG flow begins at a UV (ultraviolet) conformally invariant fixed point and ends at an IR (infrared) conformally invariant fixed point. Strominger noted that since late (early) times corresponds to the UV (IR) RG flow corresponds to evolution back in time from the future to the past. To summarize, it is conjectured that our universe is an RG flow between two conformal fixed points. Time evolution is inverse RG flow. The importance of Strominger's observation become acute when we postulate that our observed physical laws arise due to the maximization of the computational capacity of the universe. However, once we have maximized the computational capacity of our universe by some appropriate procedures or algorithms, shall leave no room for the universe to make any further updating steps(or evolutions) because our universe has been maximized already. However, if our universe is actually is expanding and RG flowing towards the future UV fix point to continually bringing in new degree of freedoms, this will provide rooms for our universe to evolute further. Another beauty of this very feature of having the origin of our universe sits in the infinite future UV fixed point is to give a sound foundation to the Ed. Fredkin's scenario, where, the whole universe can be treated as a big computer. The problem with this scenario is to answer the "what's next" question, after the universe will have evolved long enough to get the answer (that means the universe have finished computing all the possible states generated the fixed among of degree of freedom in it) and halt. On another hand, it is well observed that in almost all cellular automata simulations, one must go through all the intermediate states to find out what the end will be like: there is no way to know the future except to watch it unfold. That means our computing universe has to go through every single step before it can obtain an answer. In this way, one can therefore avoid this basic difficulties by having our universe actually RG flowing into the future UV fixed point by continually integrating in new degree of of freedom. The computing universe will never got a chance to halt and get an answer because of the constant increasement of degree of freedom (or information) during to the expansion of our universe according to the RG flow.

CS (7/20/102) said: Hi, Hao-Li: the link http://www.phys.sinica.edu.tw/~hoilai/comments.log ends with "log" so my browser can not render them correctly. BTW, if you like to shift to the "Wiki" program I am using in my site. I can send you a copy so you don't have to work a forum system from scratch. CS

Hoi-Lai (7/20/102) said: Dear CS: Thank you. I shall try to use Wiki. However, I am afraid that may cause too much time in learning the thing. Anyway, I shall try. I shall also change the .log file on Monday also. Cheers

hsiao-jing (8/15/102) said: The universe is a fantastic world and there is no limit in it !

Anonymous user using at (9/4/102) said: test

achmad sjaichu (6/26/103) said: information of accses : computation of physics