Evolution Definition and 735 Threads

I have read some amount of literature on evolution and natural selection over the years and, while I certainly learn a lot, it never seems to quite help me grok the breadth of change over deep time. So I have some rather naive thoughts that I'll phrase in the form of incredulity. They are...

Imagine potential well which in t=0 switches to a different potential well (instantly), like in the picture below. So in negative times the wavefunction density should tend to be localized in the first well, in positive times to be localized in the second well...

How how can we calculate the future evolution of a particle after the infinite square well potential is (somehow) turned off, releasing it into a free state? Assuming that it was in the ground state before.

Hi, I just completed my second year of my physics undergraduate degree. And recently did a course on Quantum Mechanics. I have a few questions regarding the basic theory and postulates, probably, because due to lack of full clarity. So, Consider a wave function ψ(x,o), which is well behaved and...

Homework Statement [/B] For a general operator ## \hat{O}##, let ##\hat{O}_{mn}(t)## be defined as: $$ \hat{O_{mn}}(t) = \int u^{*}_{m}(x,t) \hat{O} u_{n}(x,t) $$ and $$ \hat{O_{mn}} = \int u^{*}_{m}(x) \hat{O} u_{n}(x) $$ ##u_{m}## and ##u_{n}## are energy eigenstates with corresponding...

In "The Theoretical Minimum" of Susskind (p.98) it says that if we take any two basisvectors |i \rangle and |j \rangle of any orthonormal basis, and we take any linear time-development operator U, that the inner product between U(t)|i \rangle and U(t)|j \rangle should be 1 if |i \rangle=|j...

There are certain explanations on how integers might have evolved, like for example "the wings of a bird to symbolize the number two, clover--leaves three, the legs of an animal four, the fingers on his own hand five."1 Seeing all these, and making experience short--abstract, can be said to have...

I had seen a documentary about an algorithm that uses notions of evolution to deduce the equation of motion of a system by sampling a variable connected with the system. For example, they used the double pendulum case where they sampled the position of the free end of the pendulum and arrived...

Will virus evolve into something else few decades from now?

pls can u say something on coevolution convergent and divergent evolution and adaptive radiation

I'm looking for a demonstration of the equation governing the evolution of the scalar field: ## \Box \phi = \frac{1}{\sqrt{g}} \frac{ \partial}{\partial x^{\mu}} \sqrt(g)g^{(\mu)(\nu)} \frac{\partial}{\partial x^{\nu}} \phi=0## I used the lagrangian for a scalar field: ## L = \nabla_{\mu}\phi...

I went to a talk on nutrition recently which led me to do some research. Of particular interest to me is just what early humans ate, but I've also found a lot of uncertainty around what led to the evolution of the human brain. There seem to be a variety of arguments, from the claim that meat...

According Zimmermann in 1953 "evolution is the transformation of the form and mode of existence" so I want want understand what is mode of existence ?

There is a sentence in the note of " modern self -assembly theory of evolution " as follows "The accepted model of protobiogenesis suggests that information or proto-information flowed from amino acids in the geochemical matrix to protein in the first organism." Please help me to comprehend...

Hi, I am a bit confused about unitary time evolution, I understand that a closed quantum system can be explained by unitary time evolution which ensures that the probability of all possible outcomes is always 1. But for an open quantum system we can't in general explain it with a unitary time...

Hi guys, I saw mr. Nugatory's post on one of the older threads which got me a bit conceptually confused so I wanted to ask you a question regarding it. This is the original quote: "For most macroscopic systems most of the time, the wave function evolves in a way that makes quantum effects like...

Me and my friend were talking about human activities. She said that humans are creating pollution, killing so many animals creating an imbalance in food chain, global warming etc. In short we are making it worse for ourselves and other species. My reply was whatever humans do is a part of...

Homework Statement I ended up solving the problem as I was typing it up, I am posting what I did anyway as it took so long to type and might be useful to someone else. I am trying to figure out the position representation of a coherent state and it's time evolution. I should be getting a...

Hi everyone, For adibatic quantum computation one prepares the groundstate of a particular Hamiltonian and than adiabatically evolves the system to a problem Hamiltonian Hp which groundstate encodes the desired solution to a satisfiability problem. If the evolution takes place slowly the system...

Hi, my problem: following the adiabatic theorem we get an equation for the coefficients: \dot{a}_{m}=-a_{m} \langle{\psi_{m}} | \dot{\psi}_{m}\rangle - \sum_{n \neq m} \frac{\langle \psi_{m} | \dot{H}| \psi_{m}\rangle}{E_{n}-E_{m}} exp(\int_ 0^t E_{n}(t')-E_{m}(t') \, dt') we start in an...

Hi I have a pretty specific question. It is in regards to tissues in multicellular organisms. Is there any information on how different cell grouping arose in multicellular organisms? I have some ideas from what I've so far read and learned: - Would this have happened because two different...

Hello everyone, So I'm a CS major college student. I've always been interested in biology, especially evolution and genetics; but recently I've been really interested in neurobiology. I read a lot from all kind of stuff and I thought I could read some books on these subjects. What I'm looking...

Is it possible to classify all organisms which have eyes into one group and consider that they all have an evolutionary origin? I mean the eyes are used for the same function of seeing in all organisms.So it should be possible to classify them into a group on the basis of the function since eye...

What is the difference between saying "we evolved from chimpanzees" and "we and chimpanzees have a common ancestor"? The latter seems to be widely used.But don't they seem have a similar meaning? Thanks is advance,friends!

Many people have claimed that evolution started life. I'd say it did not. Life started evolution. Before there is evolution, there must be life. Am I right?

Spontaneous negative entropy reactions can occur when the internal energy decrease is greater than the negative dS*T. dG=dU-dST is spontaneous if dG is negative. The moon is receiving at least 1E8 J/s from the loss of rotational energy from the Earth's water and air. A lot more rotational...

[This thread split from https://www.physicsforums.com/threads/is-collapse-indispensable.854384/] I don't know a reference but I can indicate a proof. Ergodicity of unitary evolution of the wave function says that for given ##\psi_0## of norm 1, ##\psi(t)=e^{-itH}\psi_0## comes for some ##t##...

I read that Darwinian mutations are considered as small and directional mutations. Why is that? Regardless of the type of mutation, a mutation (or a variation) is directionless- they are random. From what I understand, the direction is given to these variations through environmental and...

Artificial Intelligence Technology can be used to develop intelligent Operation systems/ Management Systems for vehicles, buildings, factories, to control various systems.. etc. We can make robots out of it... and make intelligent equipment that improves the comfort ability of our day to day...

This paper; http://arxiv.org/abs/1601.05473, The Early Growth of the First Black Holes discusses the evolution of supermassive massive black holes [SMBH] as inferred from observations of high z quasars: which has provoked questions about the putatitve age of the universe and the time it allows...

Is it possible to work out analytically how the mass density profile ρ(r) of a ball of gas (spherically symmetric) evolve with time given the initial profile ρ0(r)? The assumption here is that the particles collapse only under the influence of gravity. I thought of this question in the process...

Currently my humanoids have powers in their genetics but they all appear similar for a given gender, age, and height. My humanoids are 4 times as tall as a human and live on an earth-like planet that is 4 times bigger than earth(the size of neptune), and has 4 times as thick of an atmosphere...

How is (5.240b) derived? I get {U^{-1}}^\dagger(t, t_0)\,U^{-1}(t, t_0)=I instead. My steps: \begin{align}<\psi(t_0)\,|\,\psi(t_0)>&=\,<U(t_0, t)\,\psi(t)\,|\,U(t_0, t)\,\psi(t)>\\ &=\,<U^{-1}(t, t_0)\,\psi(t)\,|\,U^{-1}(t, t_0)\,\psi(t)>\\ &=\,<\psi(t)\,|\,{U^{-1}}^\dagger(t, t_0)\,U^{-1}(t...

I was reading through the answer key of question 3 in an AP Biology free response (found here: https://secure-media.collegeboard.org/digitalServices/pdf/ap/ap15_biology_sg.pdf ), and it had this question: "Identify whether morphological data or amino acid sequence data are more likely to...

I have question about unitary evolution. As I understand it is assumed that unitary evolution concerns only quantum system and there are no changes in environment. First, I would like to ask if my understanding is correct? Second, from where comes this assumption? Does it comes with Schrodinger...

From a physical perspective, is the reason why one requires that the norm of a state vector (of an isolated quantum system) is conserved under time evolution to do with the fact that the state vector contains all information about the state of the system at each given time (i.e. the...

I am wondering if there is any consensus on the structure terminology of the brain. 1 - I've heard that the brain has the reptilian, mammalian(limbic) and neocortex parts that overall perform specific functions and evolved in that order. - On that note, would reptiles have had any really...

At 265 SM, and age 1.7 Million years, at 163,000 Light Years Away in the R136 cluster, is R136a. But, it shouldn't be alive now. It should have exploded given the model of Solar Mass Evolution at 200,000-375,000 Years old of age. It's in it's Wolf-Rayet phrase, but it still shouldn't be alive...

How does the magnetic field in a Z-pinch develop with time? Does it get stronger and stronger as the pinch contracts? How strong? Where can I read about it on an intermediate or perhaps advanced level? I'm looking for both books and articles. S.A.

Would you consider the foot of the modern horse to be analogous or homologous to the hand of a human? I'm confused because I'm not quite sure. I don't really see how they look similar or if they are even used for a similar purpose.

So evolution is based on the premise that successive mutations lead to phenotypic changes ultimately resulting in varied species. This despite the fact that many mutations in nature are actually deleterious to that species. The question I have then, is that if mammalian evolution produced...

Hey all, I got some question referring to the interaction picture. For example: I have the Hamiltonian ##H=sum_k w_k b_k^\dagger b_k + V(t)=H1+V(t)## When I would now have a time evolution operator: ##T exp(-i * int(H+V))##. (where T is the time ordering operator) How can I transform it...

Since the time of Darwin, biologists have looked at the history of life as a tree showing how the common ancestor of all life gave rise to all extant species. However, as we have learned more about biology, we've found that organisms do not inherit genetic information from only their direct...

We humans and chimpanzees had a common ancestor from which we seem to diverge. So that indicates that the common ancestor we had at some point gave birth to an offspring which would have slightly different features or mutations. So at some point in history of the common ancestor of humans and...

Mod note: The link in the original post contained a link to a crackpot, anti-evolution website (against our rules) that discusses a rejected paper (also against our rules). This link has been removed. Here's a link to Retraction Watch that covers the same (retracted) paper...

What's a good comprehensive book for a high school student on biology that has never studied the subject before? (Campbell seems to be college/university-level so I can't touch that)

Why is there no bones of the stages of the evolution of monkeys? :oldconfused: As we have the bones of the stages of human evolution :oldconfused:

Hello Guys I'm not an expert in biology and do not know anything about I have some questions about evolution Is evolution fact and scientifically proven? And is there of biologists who say that evolution is wrong? Thank You

Homework Statement Homework EquationsThe Attempt at a Solution Any help would be appreciated