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Anything really big is going to present serious problems - but on the other hand they are easiest to detect. Mostly the biggest ones have been identified - and cleared of suspicion. Getting precise course prediction from as far out as possible will be important - identifying one aimed in the vicinity of Earth will include near misses too until it gets closer and you better not change it's course only to discover later that you've aimed it more closely rather than deflecting it away. I don't know to what extent changing albedo can be useful - spreading black soot over part of a comet could trigger more outgassing, or white coating to reduce it. For the stony and metallic objects, no. Any "light sail" effect is probably going to be extremely small. I think any gravity effect from a spacecraft will be extremely small too; if we can move enough mass to the vicinity to change it's course it seems to me we will be better usign that capability directly to move the mass of the object. Not convinced the net idea is any help - keeping impulses, however made, below the threshold for breaking loose "rubble pile" types apart seems better. Unless they are small enough that breaking them apart is a viable option - larger ones being less likely to be rubble piles in the first place.

I am curious as to why you think the ethics of nukes or other WMD would not be pertinent to politics and "devolve" a thread. I would be shocked by your assertion that city-annihilating nukes are okay for defending your loved ones, but I know you like being provocative, so I'm not. Seriously, do you really think a weapon that could destroy all or most of human life on the planet and turn vast areas into radioactive wastelands is a reasonable sort of defense for your preferred group? (Geordie has underscored the practical problem) How long do you think we would all last if everyone embraced this view?

\.begin{array}{rcl} a&b&c\\a&b&c\\a&b&c\end{array} \begin{array}{rcl} a&b&c\\a&b&c\\a&b&c\end{array} interesting the \begin{array} self activates f(z) = \left\{ \.begin{array}{rcl} a&b&c\\a&b&c\\a&b&c\end{array} \right . \[f(z) = \left\{ \begin{array}{rcl} a&b&c\\a&b&c\\a&b&c\end{array} \right .\]

Show how to get a conformal map from the region outside a semicircle, C∖SR={(x1,x2):|x1|2+|x2|2=R2,x2≤0} to the region outside a disk D of radius R2–√ centered at the origin, C∖D , ending up with h(u)=iR+u+i⋅R2−u2−−−−−−−√2 , with u=x1+ix2 . I know that the idea is to use a Moebius transform to send the semicircle to two perpendicular lines through the origin (something like az+Rz−R ) keeping track where infinity goes, then compress the three quarters we get the outside sent too to a half plane (again keeping track of infinity), then send that to the unit circle with infinity to 0 and then invert with z→c/z to get the outside circle of right radius and send infinity back to itself, but I didn't manage to get the correct result. Could you help me?

\[\vec{v}_e+p\longrightarrow n+e^+\] \[\array{ n_e \searrow&&\nearrow n \\&\leadsto &\\p \nearrow && \searrow e^2}\]

Because ,with nuclear weapons you cannot kill your opponent without also killing yourself and anyone you care about first(or in the hours to follow) The lucky ones will be those who are killed off most quickly. Morality meets expediency

This thread has devolved into an argument about 'morality', and 'mine is better than yours'. I don't need to justify my morality to anyone on a science forum; people dying are people dying, and and my morality says if you can save those you care about, you do what you need, up to and including nuclear weapons. Nuclear weapons are simply a better more efficient weapon for killing. So were knives and swords to people with sticks; did anyone complain about the morality of using them ? So were bows and arrows to people using knives; who complained about the morality of their use ? The same for guns, tanks and bomber planes.; why is it all of a sudden about 'morality' ? And why is it more moral to kill someone( or many ) with guns, or bombs, but not nuclear weapons, @MSC

Black Holes have entropy, and therefore, temperature, This temperature is inversely proportional to its size. A solar mass Black Hole has a temperature 60 Billionths of a degree K. All other Black Holes are even colder. That means almost all Black Holes larger than a solar mass are net absorbers of mass/energy ( the CMB is at 2.7O K ) I would think that this Black Hole involved in the collision is a relatively 'new' Black Hole that hasn't been very 'active' ( injesting mass/energy ). Maybe Mordred can shed some light on this; I believe it's in his 'back yard'. As Black Holes evaporate they get smaller and hotter, and radiate copious amounts of energetic radiation ( possibly encoding information ? ) before they lose their Event Horizon and explode back into normal space-time. This can only happen far in the future when the universe has cooled enough for stellar Black Holes to be net emitters of radiation, or, if primordial microscopic Black Holes ( formed in the high energy densities shortly after the Big Bang ) are reaching the end of their lives, None have ever been detected. My thinking has aklways been that no paticle can be constrained to a point, because that would imply ( By the Heisenberg Uncertainty Principle ) that its momentum ( and speed ) could be infinite, and it could escape the Black Hole. So I, and most people don't believe a central singularity is possible; it simply means our theory ( GR ) is not applicable at these energies and scales. I suppose this depends on your definition of 'theory' and 'hypothesis', but the theory does make some testable predictions.

your welcome glad to help

Uhu.. even a layman in physics may sufficiently grasp somewhat of the Higgs mechanism with fair and relevant instructions. Thanks.

Correct now your getting it +1 on seeing that connection

I'm further taking deal of. The Fermi constant plays a crucial role in describing weak interactions. (W and Z boson actions.) Where electroweak force and the Higgs mechanism are intimately connected within the framework of the Standard Model. As shown in the formula of the VeV's effecive_action, presented here earlier. Therefore the Fermi-constant incorporates into this formula.

It's a workable descriptive not completely accurate but sufficient for a layman understanding. Getting into the renormalization aspects would be a bit too advanced it's sufficient to accept that it's a renormalized value.

Concerning the VeV ("constant"), can one define this 246 GeV amount as some type of needed minimum "transition" energy when particles are about to acquire its intrinsic mass? (Probably not that simple, but in an elementary manner?)

Well at least Chatgp got that part correct as that's precisely what it's used for. The VeV is used in a similar manner just an fyi

Hmm.. yeah, right. Somewhat above my novel understanding. The Fermi-constant should be used in calculations involving decay rates, cross-sections, and other properties related to weak interactions. (Is what ChatGPT informs.) It was proven right in the finding of Higgs boson. I.e. the Fermi-constant was also more or less proven at the success of the LHC in 2012? (Besides the Higgs theory.) Much more to learn about such subjects. /chron44

If black holes slowly loss mass over time; is there a point where they stop being black holes and devolve into something more like a neutron star? https://news.ubc.ca/2024/04/05/new-gravitational-wave-signal-neutron-stars-and-black-holes/#:~:text=The 'mass gap'%2C spanning,theory than an empty gap. If so; would that explain the potential existence of objects falling within the mass gap between small black holes and neutrons stars? Objects that may have been detected in gravitational wave data? Incredibly old ex-black holes? Dying Holes. If there is a singularity at the center of a black hole, a point of near infinite density, would that same point also be a point of near infinite pressure? All that mass trying to explode outward while the gravitational force of itself keeps everything packed in. Extra question; is the idea a theory or a hypothesis? Explain that one like I'm 5.

Here is the association of VeV to Fermi-constant Fermi's interaction - Wikipedia

Extremely interesting, thanks for posting this. It seems this may shed some light on very early evolutionary processes by which other organelles may have arisen, by being first endosymbionts and then getting integrated into the cell. I know next to nothing about this but I presume a key feature of the change would be the progressive migration of at least parts of the genetic coding needed for replication, from the endosymbiont to the nucleus of the host cell. I think I have read this is thought to have happened with mitochondria, which still retain some of their own DNA, separate from the cell nucleus. I see this work says that the template for some of the proteins the former endosymbiont needs is now in the cell nucleus, but a label is attached to them which gets them picked up by the "nitroplast". Perhaps investigation of this will help us understand how eukaryotes acquired other organelles in the long distant past.

A marine algae and a nitrogen fixing bacteria have officially teamed up and the bacteria has become a new organelle inside a marine algae. The teaming up of nitrogen fixing bacteria and plants Is not a new (Azolla carolinensis) is one but the bacteria is just in a communal relationship with the plant but this bacteria has actually become an organelle inside the algae cells much like mitochondria or chloroplasts in other cells, this new organelle has been dubbed Nitroplast. https://newscenter.lbl.gov/2024/04/17/scientists-discover-first-nitrogen-fixing-organelle/ I am remembering reading of another animal that has evolved something similar that allowed it live in anoxic water in the black sea. If I remember correctly it was a ctenophore, anyone remember this?

A possible antineutrino cross section calculation massless case \[\vec{v}_e+p\longrightarrow n+e^+\] Fermi constant=\(1.1663787(6)*10^{-4} GeV^{-2}\) \[\frac{d\sigma}{d\Omega}=\frac{S|M|^2\acute{p}^2}{M_2|\vec{p_1}|2|\vec{p_1}|(E_1+m_2c^2)-|\vec{p_1}|\prime{E_1}cos\theta}\] Fermi theory \[|M|^2=E\acute{E}|M_0^2|=E\acute{E}(M_Pc^2)^2G^2_F\] \[\frac{d\sigma}{d\Omega}=(\frac{h}{8\pi}^2)\frac{M_pc^4(\acute{E})^2G^3_F}{[(E+M_p^2)-Ecos\theta]}\] \[\frac{d\sigma}{d\Omega}=(\frac{h}{8\pi}^2)\frac{M_pc^4(\acute{E})^2G^3_F}{M_pc^2}(1+\mathcal{O}(\frac{E}{M_oc^2})\] \[\sigma=(\frac{\hbar cG_F\acute{E}^2}{8\pi})^2\simeq 10^{-45} cm^2\] \

you won't find that equation in a textbook, textbooks only show the basic equations in math speak in this case you would usually see the first order equation this delves into the second order. just as most textbooks won't show the equation \[H_z=H_o\sqrt{\Omega_m(1+z)^3+\Omega_{rad}(1+z)^4+\Omega_{\Lambda}}\] this shows the expansion rate H varies over time (it will also help to better understand the first equation as well as the Hogg paper I posted. now as you mentioned DM and DE one line of research is Higgs being responsible. Sterile neutrinos (right hand are heavier than left hand neutrinos ) antimatter and matter neutrinos. so the calculated abundance could fall into range \[\Omega_pdmh^2=\frac{G^{3/2}T_0^3h^2}{H_0\sigma v}=\frac{3*10-{27} cm^3s^{-1}}{\sigma v}\] research is still on going. Just as the equation of state for the Higgs field may explain inflation as well as the cosmological constant. That should sufficiently show that what really goes on in the professional circles isn't something one can simply google at best that just gives hints

Understand this and you clear the confusion. F = ma Weight = Mass x gravitational acceleration lb force = lb mass x g/32.2 ie if we equate weight numerically with mass, we're implicitly adopting some unit of acceleration that has the numerical value of 1 at the earth's surface. As @exchemist has pointed out, this creates a great deal of needless complications in US technical literature. Many equations end up littered with this dimensional constant of 32.2 simply to maintain this unity factor between weight and mass. Either that or adopt that most wonderfully named of all units, the slug foot. See https://en.wikipedia.org/wiki/Gc_(engineering) Only approximately. The higher levels of the earth's atmosphere are subject to a lower gravitational acceleration due to their increased distance from the centre of mass so they weigh less per unit mass. This illustrates quite nicely how careless application of the unity assumption can simply lead to incorrect results.

! Moderator Note Rule 2.11 Solicitations requiring non-disclosure or confidentiality agreements, or insisting that discussions must take place privately, are not permitted. We are here to discuss science, in the open (and "I have an idea, can someone do the math for me" typically woefully underestimates the amount of effort this involves).

no coordinate choice affects the mass distribution. I could describe the universe in numerous different coordinate choices example Euclidean, spherical cylindrical etc without causing any difference. It is precisely why we use invariance. The mathematics is set up that way so that we do not have any coordinate choice dependency. you know full well GR fully describes time dilation the FLRW metric is a GR solution. We don't arbitrarily choose DM and DE as the full explanation those two terms are simply placeholders until we can determine the cause of each. We still can measure their effects through indirect evidence. I rarely give downvotes so its someone else. As far as sampling range is concerned, redshift is only one of many pieces of evidence of an expanding universe. In point of detail its not even close to the strongest evidence. Its the one most ppl are familiar with but the real evidence comes from our thermodynamic laws in regards to temperature and how it influences the SM model of particles via processes such as BB nucleosynthesis in regards to the CMB. One danger of trying to understand cosmology by rote instead of learning the math is that too often you get incorrect information. I will give an example if I looked up hydrogen and its temperature it could form with stability a google search will state 3000 kelvin. However if one knows how to use the Saha equations that would reveal that value equates to 75 % of the potential hydrogen. Hydrogen can start to form as low as 6000 kelvin=25% 4000 kelvin for 50 %. That is just one example. however knowing this one can study the metallicity of our universe evolution via hydrogen, lithium, deuterium etc. So I just described another piece of evidence for expansion. In other words were not restricted to redshift to determine if our universe is expanding . In point of detail we do not rely on redshift in cosmology it is too full of other influences such as gravitational redshift, transverse redshift, Integrated Sache-Wolfe effect, Doppler redshift. etc etc. We examine all pieces of possible evidence to confirm the accuracy of cosmological redshift. Nor do we use the generic formula everyone sees on google. https://en.wikipedia.org/wiki/Redshift this formula only works for nearby objects it loses accuracy as near as one MPC. The full formula includes the influence of the evolution history of matter, radiation and Lambda. details can be found here "Distance measures in cosmology" David W. Hogg https://arxiv.org/abs/astro-ph/9905116 side note the paper also applies to luminosity distance we also have a different formula for Luminosity distance than what one would google. \[H_O dl=(1+z)|\Omega_k|^{-1/2}sinn[\Omega_k^{1/2} \int^z_o\frac{d\acute{z}}{\sqrt{(1+\acute{z})^2\Omega_R+(1+\acute{z}\Omega_m-\acute{z})(2+\acute{z})\Omega_\Lambda}}]\] What this equation shows is that matter, radiation and Lambda density not only influences expansion rates it also influences redshift and luminosity as well as any curvature term k