Robert McNees

@mcnees.bsky.social

16736 Followers 802 Following

Physicist and Professor at a university in Chicago. I study black holes, quantum gravity, and cosmology. Rocky Top, Tar Heel. Reposts are spooky action at a distance. My views, not my employer's. https://jacobi.luc.edu https://mcnees.github.io

A Lake Michigan beach at dusk, with a purple sky lightening to a dusty peach and rose in the west. A jetty stretches out into the lake, a small tower with a glowing red light at its end.
A dusky blue evening sky with pink and orange wisps of clouds stretched horizontally across the sky, turning into a peachy orange glow at the horizon. Foreground trees are black silhouettes against the sky.
The epic handshake meme. One arm says “bicep,” the other says “groin,” and the clasped hands say “Do not enter the heart from here”
A photo of the Apollo 11 Lunar Module returning to orbit to rejoin the Command Module. The moon is gray and covers the bottom half of the photo; there is some variation between darker and lighter shades across the surface. The sky above the moon is black, except for the blue, green, and white quarter-Earth rising above the horizon.
A scruffy blonde golden doodle looks very clean and is curled up on a white towel.
A fluffy golden doodle puppy jumps into the air spread eagle with mouth wide open to try to catch a tennis ball
Aragorn and Theoden have curly mushroom hair and cross earrings. “Chat, the beacon notification just hit. Gondor's asking for a carry.” “Say less.”
The distant white triangle of a sailboat is just visible on the horizon of a green-blue Lake Michigan, beneath a bright blue sky.
A brown bunny sits beneath a cluster of black eyed Susans, with a flower and stem hanging out of its mouth.
A pair of baby bunnies nibble on grass and clover poking up from beneath paving stones. They have gray-brown fur and are very small and round (the bunnies, not the paving stones).
Clearly the initial quantum could not conceal in itself the whole course of evolution; but, according to the principle of indeterminacy, that is not necessary. Our world is now understood to be a world where something really happens; the whole story of the world need not have been written down in the first quantum like a song on the disc of a phonograph. The whole matter of the world must have been present at the beginning, but the story it has to tell may be written step by step. G. Lemaître.
Now, in atomic processes, the notions of space and time are no more than statistical notions; they fade out when applied to individual phenomena involving but a small number of quanta. If the world has begun with a single quantum, the notions of space and time would altogether fail to have any meaning at the beginning; they would only begin to have a sensible meaning when the original quantum had been divided into a sufficient number of quanta. If this suggestion is correct, the beginning of the world happened a little before the beginning of space and time. I think that such a beginning of the world is far enough from the present order of Nature to be not at all repugnant.
The Beginning of the World from the Point of View of Quantum Theory. SIR ARTHUR EDDINGTON states that, philosophic. ally, the notion of a beginning of the present order of Nature is repugnant to him. I would rather be inclined to think that the present state of quantum theory suggests a beginning of the world very different from the present order of Nature. Thermodynamical principles from the point of view of quantum theory may be stated as follows: (1) Energy of constant total amount is distributed in discrete quanta. (2) The number of distinct quanta is ever increasing. If we go back in the course of time we must find fewer and fewer quanta, until we find all the energy of the universe packed in a few or even in a unique quantum.
Black and white photo of diocesan priest Georges Lemaître. He is wearing a dark jacket and shirt with his white priest’s collar. He has glasses on, with his hair combed back, and is looking at the camera with a neutral expression.
A text message reads Maybe: Ally If you're a non-smoker, you could receive great savings on your policy. Interested in more details?
a juvenile possum with bushy gray-brown fut, a white face, black ears, and a pink nose and toes, hangs out on top of a chain link fence. It is being very still.
A fuzzy brown rabbit sits on a patio underneath hostas and black-eyed Susans, grooming himself after eating clover.
The same juvenile possum atop the chain link fence on one side of my yard.
A young possum sits atop a chain link fence. It has gray-brown fur, a white face, black ears, and very pink nose and toes.
The same white "stack plot" but on a light blue background. The lines, which record data from a radio telescope, form what looks like a mountain range.
The cover of the Joy Division album "Unknown Pleasures." It features a white "stack plot" on a black background. The lines, which record data from a radio telescope, form what looks like a mountain range.
Gertrude Scharff, at the age of 11 or 12. Her hair is short. She is smiling and looking just to the left of and above the camera.
The C-14 source was produced in Oak Ridge and allocated by the Atomic Energy Commission. This work was supported by the Office of Naval Research under Contract No. Nб-ori-71.
The beginning of the letter reads: Identification of Beta-Rays with Atomic Electrons M. GOLDHABER AND GERTRUDE SCHARFF-GOLDHABER Department of Physics, University of Illinois, Urbana, Illinois May 8, 1948 THE old question whether beta rays are identical wieh atomic electrons was recently reviewed by Crane.' When this problem was much discussed about ten years ago, experiments by Zahn and Spees? set doubts at rest by showing that the value of e/m for beta-rays does not differ from the value found for atomic electrons by more than 1.5 percent. While this and other indirect evidence support the assumption that beta-rays and atomic electrons are identical, the question remains "... whether or not experiments can exclude the possibility that, for example, the spin of the beta-particle is different from one-half unit, with only a slight effect upon the mass. This kind of question should be answered as precisely as possible for the record. ..."
The beginning of the letter reads: Spontaneous Emission of Neutrons from Uranium G. SCHARFF-GOLDHABER AND G. S. KLAIBER Department of Physics, University of Illinois, Urbana, Illinois May 18, 1942 FLEROV and Petrzhak have established the existence of spontaneous fission in uranium by recording the heavy fission fragments with a uranium-coated ionization chamber. The partial decay constant of the "average uranium atom" calculated from their data lies between 2X10-25 and 2X10-24 sec. for this process. It seemed possible that the mechanism of spontaneous fission might be different from that of induced fission, in particular that no neutrons might be split off in the former process. Libby had previously made an unsuccessful attempt to find spontaneous fission neutrons with the help of a boron counter...
Black and white photo of Gertrude Scharff Goldhaber. She wears a sleeveless white blouse with a white collar, along with a necklace that is hard to see clearly. Her hair is short and she is smiling at the camera.
A t-shirt that says “DAD”
A google page says: People also ask Is chaos theory LGBTQ?
A scruffy blonde golden doodle on a beach at sunset with Lake Michigan in the background. Looking eastward, the lake is a silvery blue and the sky is pink, peach, yellow, and blue.
Striped red and white zinnias emerge from a planter. Large green leaves surround the stems.
Mother Hen's young song Egghead Jr is reading a book titled "Splitting the Fourth Dimension"
Two leprechauns talking to each other in a Loony Tunes short. They are both wearing green jackets and hats, have rummy noses, and are smoking pipes.
A tiny brown bunny sitting in a deep patch of clover by a garden bed.
The top part of the website reads: Conventions, Definitions, Identities, and Formulas Last modified: July 10, 2026. A collection of results useful enough for me to keep them all in one place. Please let me know if you find typos or mistakes! Several people have contacted me to say they used some of these results in published papers. That's great! If you use this reference for something that ends up in a publication, please consider including a citation with my name, the page title, and the url. Here's how to do it in REVTeX (thanks, Tim Wiser), and here's the BibTeX code I used in a recent paper. Recent changes can be found at the bottom of the page. Table of Contents 1. Curvature Tensors 2. Lie Derivatives 3. Differential Forms 4. Euler Densities 5. Spacelike and Timelike Hypersurfaces 6. Sign Conventions for the Action 7. Hamiltonian Formulation for Evolution Along a Spatial Direction 8. Conformal Transformations 9. Small Variations of the Metric 10. The ADM Decomposition 11. Converting to ADM Variables
A headline reads “The mystery surrounding Mitch McConnell’s absence”
Black and white photo of Edith Quimby. She is seen from the shoulder up, and is looking just to the right of the photographer. Her hair is wavy and combed back, parted on her right.
Black and white photograph of a young OIiver Sacks on his motorcycle. He is wearing blue jeans and a black leather jacker. His hair is cut very short, and he is looking to the right of the photographer.
A scruffy blonde golden doodle peers through the corner of a glass door, looking forlorn and wondering why he was abandoned.
A black and white scan of the front page of the Roswell Daily Record newspaper. The headline reads "RAAF Captures Flying Saucer on Ranch in Roswell Region." The sub-hed says "No Details of Flying Disk are Revealed." Photos on the front page describe a flood in Grand Tower, Illinois, and the family of the former king of Romania traveling to Cuba and Mexico.
A black and white photo of Emmy Noether, Marie-Louise Dubreil-Jacotin, and Paul Dubreil. They are sitting at a table that is covered in a checkered tablecloth. Noether is closest to the camera -- she is smiling over her right shoulder at the photographer and her right hand is resting on the table. She is wearing a long coat, and classes with wire frames. Mary-Louise Dubreil-Jacotin is next to her. Rather than looking at the photographer, she is looking at Noether and smiling. Dubreil-Jacotin is wearing a light jacket, blouse, and a black hat that covers her ears. Her husband Paul is at the end of the table, and also appears to be looking at Noether. He has a light overcoat and is wearing a dark suit with a white collared shirt.
A black and white photo of Marie-Louise Dubreil-Jacotin. She is shown from the side, and from the shoulders up, with her head turned to her left to face the camera. She has short dark hair curled up at the bottom, and appears to be wearing a gown than sits low on her shoulders. She is smiling, not looking directly at the camera but slightly below and to the left. A necklace is just visible, but the photo is low resolution so it is hard to make out details.
A scruffy blonde golden doodle lounging on a midcentury modern armchair.
A scruffy blonde golden doodle sploots on a window seat, looking flat as a pancake.
A cardinal perched on the edge of our patio table. The black markings on its face make it look like it is glaring and angry.
A sign that shows a hand dropping several small cubes next to a bear. It’s supposed to be food but it looks like dice. A red bar and circle indicates that it is not allowed.
A bee sits atop a bright fuchsia flower, gathering pollen.
Purple and orange clouds in the east catch the sunset in the west out over the lake.
Dark gray clouds pile up over the lake. A sandy beach is in the foreground.
For surgeon general C. Everett Koop says “She’s a witch!” Lisa Simpson responds “Please, Dr. Koop. Let me demonstrate.”
Black and white photo of Dr. Samuel P. Massie. He is wearing a long white lab coat over a gray suit, with a white collared shirt and a tie about the same color as the suit. Dr. Massie is looking to the right of the photographer and smiling at someone out of the frame. He has short silvering hair. There is a bench with bottles of chemicals in the background behind him.
A mosaic featuring an array of skins (themes) for the ancient mp3 player WinAmp.
The obituary in Nature begins: HARRIET BROOKS (MRS. FRANK PITCHER) HARRIET BROOKS (MRS. FRANK PITCHER) who died in Montreal on April 17, was well-known in the years 1901-5 for her original contributions to the then youthful science of radioactivity. A distinguished graduate of McGill University, she was one of the first research workers with Prof. (now Lord) Rutherford in Montreal. She observed that the decay of the active deposit of radium and actinium depended in a marked way on the time of exposure to the respective emanations and determined the curve of decay for very short exposures. This work, which was done before the transformation theory of radioactive substances was put forward, assisted in unravelling the complex transformations which occur in these deposits. With Rutherford she determined the rate of diffusion of the radium emanation into air and other gases. These experiments were at the time of much significance, for they showed that the radium emanation diffused like a gas of heavy at least 100.
The passage reads: "I think it is a duty I owe to my profession and to my sex to show that a woman has a right to the practice of her profession and cannot be condemned to abandon it merely because she marries. I cannot conceive how women's colleges, inviting and encouraging women to enter professions can be justly founded or maintained denying such a principle."
The passage reads: The institution believes that the son and daughter of the man in poor circumstances is as much entitled to college training as are the children of the well-to-do. This program appealed so strongly to Miss Gill that she elected to spend her last years in making whatever contribution she could to its development. She was one of group of more than 175 workers who are directing the studies and other activities of an army of nearly 3,000 students, most of whom come from the Southern mountains and •do manual labor in order to pay part of their school expenses.
The page reads: A Volatile Product from Radium. In the course of some recent experiments on the excited radio-activity from the radium emanation, some evidence has been obtained which points to the conclusion that the emanation X of radium at one stage of the changes which it undergoes after being deposited on a solid body is slightly volatile even at ordinary temperatures. The effect which gives rise to this conclusion was first noticed in some observations on the rate of decay of the part of the excited activity deposited on a plate of copper immersed for a short time in dilute hydrochloric acid, in which the activity from a platinum wire exposed for a time to the radium emanation had been dissolved. When the copper plate with its active deposit had been placed inside a testing vessel and removed after a few minutes, it was noticed that a temporary activity, in some cases equal in amount to one or two per cent. of the activity of the plate, was excited on the walls of the vessel. This activity increased to about three times its original value in the course of thirty minutes after the... NO. 1812, VOL. 70]
Black and white photo of Harriet Brooks. She has on a black dress with a high column collar, and she is looking to the right of the photographer.
Close-up of a book with a plain white cover featuring black text. The title "Quicksilver" is stylized in a 18th century script. The cover reads: THE BAROQUE CYCLE IS ABOUT TO BEGIN... 必 neal stephenson Quicksilver VOLUME ONE OF THE BAROQUE CYCLE ON SALE SEPTEMBER 23, 2003 This is galley number 8 of 435. The resale of these numbered galleys is prohibited. UNCORRECTED PROOF NOT FOR SALE
The image mimics the layout of a magic user spell from the 1st edition Advanced Dungeons & Dragons Player's Handbook. It reads: Sum Over All Small Things (Calculus/Necromantic) Level: 5 Components: V, S, M Range: Touch Casting Time: Variable Duration: Permanent Saving Throw: Special Area of Effect: Chalkboard / Piece of paper Explanation/Description: By means of this spell, the caster performs a sum over an infinite number of infinitesimally small things to produce a finite result. The caster must make a saving throw each round. A successful save means the sum has been performed. A failed save causes the caster to suffer from the effects of the fourth level magic user spell confusion (q.v.), and delays the next saving throw for another two rounds. The material component of this spell is a tattered copy of “Tables of Integrals, Series, and Products” by the sages Gradshteyn and Ryzhik.