Formation Definition and 508 Threads

I've spent the past few days trying to find an answer to a question I have about the formation of massive black holes in the early Universe. It is possible that my search parameters were poorly formulated. As I understand the issue, according to our current theories, massive black holes 'should...

What is the consensus on how long it would take for a galaxy to form similar to the ones which I am reading about here with Z=20? Galaxy formation time is probably of much interest right now. Perhaps formation was much quicker shortly after the BB with higher gas densities...

The solution manual says that before water enters the hollow So here an air bubble of radius R will escape from the sphere. The excess of pressure inside the bubble is 2T/R. The excess of pressure prevents the penetration of water into the sphere. Water begins to penetrate when the excess of...

If you read articles like The James Webb Space Telescope prompts a rethink of how galaxies form you see that recent images of early galaxies have thrown some doubt on theories of how galaxies have formed and when they started forming. But if you read about the JWST in the popular media -- and...

This is actually a two-part question: 1) According to the Copenhagen Interpretation, atoms have energy bands but there's no explanation of how these bands are derived, or why they only form for protons/antiprotons. Any thoughts? 2) The Copenhagen Interpretation mentions that when an atom's...

Dear all, I'm going to give a course about black holes at an astrophysics association. The public will consist mainly of lay persons, perhaps wit a little bit of physics background. My background in General Relativity is good, but my background in astrophysics at bit less. My question is if you...

Hello, I'm in grade 12, writing a term paper on brown dwarfs and am currently looking at their formation. I have now come across the formation of brown dwarfs in so-called "filaments" (link to the page below), but can't find out anything about them, except for the fact that they are filamentary...

Thanks to the JWST, we have this stunning picture. The APOD description says What are the processes that eject material at this stage?

I found an old article (https://journals.aps.org/pr/abstract/10.1103/PhysRev.137.B1379) which talks about conservation of energy in an expanding space. Apparently, the author found that energy is conserved at local scales (like the motion of planets in our solar system) as one would expect, but...

Referencing this posted on the Webb thread: https://www.quantamagazine.org/two-weeks-in-the-webb-space-telescope-is-reshaping-astronomy-20220725/ So will they able to do spectroscopy on GLASS-z13, the galaxy dating 300M after the big bang? Do they expect to see any heavier elements in a galaxy...

I was studying wind formation from the continent to the sea during day (direct circulation) and the explanation I found in almost all the textbooks was that: 1. In the continent during day the ground becomes hotter 2. The particles in the air increases their temperatures due to induction 3. When...

Hello , I am studying lipids and a point got me confused . it is said that beside the fatty acid we have glycerol and sphingosine that forms the backbone of the lipid . is the lipid formed by those 3 components at the same time (fatty acid +glycerol +sphingosine ) or it is formed by the fatty...

I was watching a program on the formation of the Great Lakes, and it is quite interesting and fascinating. The huge salt deposits under the Lakes Michigan, Huron and Erie and fossilized sea sponges provide evidence of a salt water sea in the past. Limestone formed from successive corral reefs...

This is just a rough estimate of what a simple bock universe might be to an observer in the red worldline on the left side, and what it is to an observer in one of the blue worldlines in the graph on the right side. In the graph on the left side, two blue objects moved past the red object very...

I read in Wikipedia that fog is formed when the water vapor in air is condensed to form liquid water that are suspended around condensation nuclei. Fog or clouds don't move from some place but appear in places through condensation. Now there is something about dew point which has to do with the...

Dear all, For a new book I'm writing I'm investigating some common misconceptions in physics. And of course, that means confronting myself with my own confusion. One thing I've never got clear in my head, and which I find hard to answer using google and my textbooks on GR, is the following: how...

I'm very much an amateur with a keen interest in space/the universe and it occurred to me the other day that our solar system could have been formed in exactly the same way that it is hypothesised that the Moon/Earth system formed through the (proposed) collision of Theia and the proto-Earth...

Could matter have formed structures in the universe, like galaxies, without the presence of dark matter?

Solution as stated in the problem description.

Hi all. I am trying to do MATLAB simulations for generation of SINE Dipole using two hydrophones spaced distance 'd' apart for signal coming from direction 'DOA'. The MATLAB code is given below. The confusion is that there is constant phase difference of 90 degree b/w SINE Dipole generated using...

I will refer to this paper for some relevant bits of theory. They write that the component of the force between the solid and liquid parallel to the solid-liquid interface, which appears near the contact line (in the dotted region), is ##\gamma_{SV} + \gamma_{LV} - \gamma_{SL}##, which by...

Hello all! I wrote a reaction mechanism for a sequence that forms an amide. Do you agree with my answer? Thanks for your help!

Hello All, I wanted some insight on my answer to this problem. Lets say we have the reaction PCl3(g) + Cl2(g) ↔PCl5(g) ΔH0=-111KJ So for this reaction we know it is exothermic (because my textbook told me). But I want to make sure I understand why it is. If I were to look at this reaction and...

I watched a video lately describing how life could have arisen on Earth near the hydrothermal vents, with the exact way it formed being unknown. This made me wonder could there be a very simple configuration of DNA (or RNA?) that could give rise to life? I'm thinking the earliest life forms may...

Here is the paper. I have ran it by one of the guys first https://advances.sciencemag.org/content/6/7/eaay7604.full In terms of abiogenesis does this have any impact? Water also.

I'm having difficulties uploading my work to this system at the moment, but I have currently attempted 1,3-cycloaddition between the furoxan and phenylacetylene. However, unless a sigmatropic rearrangement occurs (which, as far as I can conclude, leads to instability with charges), this places...

Hi all, I would like to ask why is there ice formation on the exterior of the pipes between compressor to reactor when there is no flow passing through or what kind of phenomenon is this? My colleagues have suggested PV=nRT and adiabatic process as the possible reasons but I still feel that...

Here is my work** Magnesium cations (Mg2+) Oxide anions (O 2-) A magnesium ion has a 2+ charge and the oxygen atom has a 2- charge. The formula for the ionic compound is MgO.

I can't understand how dark matter can form structures from the initial near uniform distribution as shown in simulation like those of the Eagle project http://icc.dur.ac.uk/Eagle/index.php. I understand how the initial density fluctuation are amplified and dark (and ordinary) matter start to...

So as the title suggests, I'm looking for some introductory books on Star Formation. I have a rudementary idea of the concept from a module I took last year which I found really interesting. I'm looking to apply for a research scholarship next academic year in which I would undertake a research...

My professor taught me that a internally statically determinate truss is formed by having one basic truss - the triangular truss consisting of three joints and three members: and then repeatedly adding two members and a joint: So, it makes sense why this is a statically determinate truss...

I am curious about the standard enthalpies of formation of carbon nanotubes, diamond, carbon buckyballs, graphene, etc. I read from physics forums that the standard enthalpies of formation of these allotropes of carbon are small. However, since diamond is fabricated naturally under extreme...

How much impact does the presence of the cosmological constant have on the formation of structures in the universe? On a larger scale, is there less structure formation because of the presence of the cosmological constant?

So I'm learning in a class that coal is made when land plants (in swamps) die and then get buried in sediments, and with the Earth's pressure/temperature the plants become coal. Then I learned that when ocean plants (like algae and plankton) die, they also get buried in sediments in the sea...

Hello. If we consider PBH formation from collapse of large density perturbation in the early Universe, a mass PBH depends on density contrast as And δ must be larger then . Also we have β — an abundance of black holes, it's the ratio of the PBH energy density to the total energy density, this...

why do we use the entalphy of formation of water at standard conditions to calculate the entalphy of a reaction even if water is not gas at 1bar and 298K

It seems that the super-massive black holes at the centres of galaxies formed very early in the history of the galaxies (e.g ULAS J1342+0928, which had about 800 million solar masses 13.1 billion years ago). Presumably, in the very early days, matter in the universe was much less clumped than...

The enthalpy of formation equation: ΔHƒ°reaction=∑Δhƒ°(products)-ΣΔHƒ°(reactants) When using the enthalpy of formation equation you get: -2010-((-394x3)+(-286x4))= 316Kjmol-1 However, this answer is wrong. On the mark scheme, the answer is -316Kjmol-1. So I used the enthalpy of combustion...

This is probably more of a p-chem question but I figure you guys are smart enough to answer this. FREEZING LEVEL CALCULATION: Per FAA "A standard temperature lapse rate is when the temperature decreases at the rate of approximately 3.5 °F or 2 °C per thousand feet up to 36,000 feet" Easy...

Last week I posted in General Physics some questions about what happens in a collapsing gas cloud, and I was advised that total angular momentum is conserved. I thought of asking for extra clarification here, as that seems really amazing -- I apologize for asking the same thing twice. I use a...

Homework Statement My question. When studying conics, the parabola circle, and ellipse can be easily see by passing a plane through a double cone. The hyperbola is generated when the plane is passed through the double cone where it passes through the top and the bottom cone. My question is...

Are there theories to explain the formation of supermassive black holes?

Yesterday morning, before work, I cooked eggs in canola oil in a cast-iron pan. Afterward, I rinsed out the pan and heated it to dry it. By mistake, I left the stove on. When I returned home, in addition to my house being smokey and smelling like IHOP, my cast-iron pan was lined with a...

Hi, I want to ask , is there any example in chemistry when during covalent bond formation the repulsive forces dominate and no bond is formed. Thanks

Homework Statement True or false: When two atoms are equally electronegative, they will interact to form polar covalent bonds. Homework Equations Atoms with similar or equal electronegativities share electrons between them and are connected by covalent bonds. Atoms with large differences in...

Homework Statement A mass m slides down a frictionless plane that is inclined at angle θ. Show, by considering the force of constraint in the Lagrangian formulation, that the normal force from the plane on the mass is the familiar mg cos(θ). Hint: Consider the Normal force to be the result of...

Thought experiment: single use of "magic" Setup: Let's assume we have a giant ball of water in space. Magic: Let's assume the water does not compress its center under its own gravity. (Constant density of 1 g/cm^3) Basic stuff: The mass of this ball of water, (since it does not compress)...

Hi, I would like to raise a question about Role of magnetic field while formation of small to medium scale stars emerging from nebula ?

I know my last question on radicals' interaction with luminol didn't get much attention, perhaps it was too specific. Please could I ask a last question, I understand that when radicals are formed via bond breaking this is called the bond-dissociation energy, but is there an energy associated...

Hello. First post here so hi all. My question(s) is regarding the formation of solar masses by accretion of gases and dust. From what I understand, stars are formed by large clouds of gasses and dust particles pulling together and with enough gravity, (magnetic fields), and time. A fusion...