count_of_monte_carlo @ count_of_monte_carlo @lemmy.world

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That’s correct, but I wasn’t implying the opposite; I hope my comment doesn’t read that way.

A fraction of the vaccinated population will not have 100% immunity. Even among healthy, non-immunocompromised people vaccines generally don’t have a 100% efficacy. For example, annual flu vaccines vary in efficacy, but are often around 50%.

As I said in my comment, herd immunity is a form of indirect protection. Keeping a disease from being able to spread prevents people from being exposed at all, regardless of their immunity status. If enough people are unvaccinated and there is no herd immunity, then that increases the risk for the whole population - even those who were vaccinated since generally that doesn’t guarantee immunity.

There are certainly arguments to be made about bodily autonomy and weighing individual rights against those of society. However, the idea that “the decision to not be vaccinated is an individual choice that doesn’t harm others” is incorrect, and therefore not a great argument against vaccine mandates.

if they don't want to get vaccinated then it still won't affect vaccinated folks.

This is actually not true, since enough people being unvaccinated can prevent herd immunity from protecting everyone.

Herd immunity is an indirect protection from an infectious disease that occurs when enough of a population has immunity (either from vaccination or prior infection). When enough people are immune, infections are unable to spread and outbreaks naturally end. This protects people within the population who don’t have immunity (unable to be vaccinated for medical reasons, vaccinated but didn’t get complete immunity, too young for the vaccine, immunocompromised, etc). It also protects those with some immunity who might still have a less severe infection.

The vaccination rate required for herd immunity depends on how infectious a particular disease is. Measles is particularly infectious, and a 95% vaccination rate is considered necessary for herd immunity. Many parts of the US have rates lower than that, which is why measles outbreaks are becoming common after the disease had basically been eradicated for decades.

That’s a good question - I hadn’t considered the size of the interaction region. It’s actually really big!

These high energy neutrinos produce particles like muons that can penetrate pretty far through the detector. IceCube is a 1km cube of ice (with light detectors throughout) and if you look at images of events, many of the detectors will light up along the muon track length. So that’s hundreds of meters long. I think that would appear as a large and faint blue haze.

The Cherenkov light is pretty directional though (in the forward direction) so it won’t necessarily be a uniformly bright glow. It’ll depend somewhat on your viewing angle relative to the incoming neutrino.

image source

I imagine it would be visible under the right conditions. It’s been demonstrated that the human eye can detect single photons. The Cherenkov photons follow an energy distribution, but for simplicity we can assume they are blue light (450 nm), which is 2.7 eV per photon. IceCube is designed to detect neutrinos with energies greater than 1 TeV. Assuming full conversion of neutrino energy to Cherenkov photons, that’s 370 billion photons per detection event. Pretty good odds on seeing that.

You are not being singled out. I’ve given the author of the other comment a warning with the opportunity to fix the rule violation with an edit, same as you. In both cases, the comments will be removed if they aren’t addressed in a reasonable timeframe.

Antimatter interacts with regular matter in more ways than just annihilation. Annihilation just happens to be a process that’s uniquely available to antiparticles and has a high probability of occurring. This is because antiparticles have both opposite electric charges to standard particles and opposite color charge, so annihilation between particle/anti particle pairs conserves these quantities.

It’s unlikely that there’s an anti-matter equivalent of dark matter. If there was, we’d expect to see annihilation radiation, such as the 511 keV photons emitted when positron+electron pairs annihilate.

Yep. In fact there’s a process called inverse Compton scattering that essentially works this way. In ordinary Compton scattering, a photon scatters off a stationary electron and typically leaves with less energy (since the electron gets a kinetic kick). In inverse Compton scattering, a photon collides with a moving electron which can cause the photon to gain energy.

One application of this is to produce gamma-ray beams. You take a beam of light (often from a laser) and collide it head on with a beam of relativistic electrons traveling in the opposite direction. In the electron rest frame, the photon has gamma-ray energy, while in the lab frame it might only be visible light. The back-scattered photon can then be boosted to the gamma regime in the lab frame, and now you’ve got a gamma-ray beam.

A black hole is believed to contain a singularity with all of the mass as a single point. So this is well past the point of baryonic matter and in a region where our physics models break down.

If you just take the total mass of a black hole and divide it by the volume of the Schwarzschild radius (aka event horizon) you get a density MUCH greater than a neutron star. This isn’t a useful measure of the black hole density though, since all of the mass is at a single point of presumably infinite density.

Neutron stars are the most compact form of matter that we know about; they’re even denser than the nucleus of an atom.

Neutrons, protons and electrons are fermions, meaning they must obey the Pauli exclusion principle. No two neutrons (or protons or electrons) can be in the same quantum mechanical state. If you take ordinary star matter (plasma made of dissociated protons and electrons) and squeeze it, eventually the electrons will nearly overlap in their states. You’d have two electrons with nearly the same energy, spin and location. They cannot overlap though, so this creates a repulsive force that prevents the matter from further compression; this is called the electron degeneracy pressure.

If the compressive force overcomes this pressure, then the electrons can capture on the protons to form neutrons. Neutrons and protons also have degeneracy pressures, but they can be packed much more densely than electrons. This is because their wavelength is shorter. The wavelength of a massive particle is inversely proportional to its mass, and protons and electrons are about 2000 times the mass of electrons. So compressed ordinary matter will inevitably become pure neutrons, simply because this is the most compact form.

A pure electron or pure proton star wouldn’t be as compact because both are charged particles so there would be Coulomb repulsion (this isn’t an issue in ordinary matter since the number of electrons and protons is roughly equal). You’d also need to somehow separate the electrons from the protons, and this isn’t a process that would naturally occur in a collapsing star.

They would die immediately.

Breaking atomic and molecular bonds is what ionizing radiation such as gamma rays or neutrons does to a human body, so this scenario would be sort of like an extreme, unrealistically high dose of radiation.

Immediately after all bonds are broken, atoms would react and start to form new bonds. In some cases these bonds would reform correctly- for example, water being remade as H2O. In many cases alternative bonds would form which could make substances incompatible with life- say H2O2, aka hydrogen peroxide. Basic cellular and nerve function wouldn’t work, hence the instant death.

Lepton number is an observationally conserved quantity. As far as I know there’s no fundamental reason for it to be conserved (and indeed there are searches for physics beyond the standard model that would violate it) but it’s been found to generally be conserved in reactions so far. Lepton particles have a lepton number of +1, lepton antiparticles have -1.

There’s a similar conserved quantity known as the baryon number, with a similar definition. Protons and neutrons (baryons) have values of +1, anti-protons and anti-neutrons are -1.

An example: consider the beta- decay of a neutron, baryon number +1 and lepton number 0. It emits a proton (baryon number +1), an electron (lepton +1), and an electron anti-neutrino (lepton -1). Total lepton number of the decay products is 1-1=0, so the value is conserved.

Locking because the discussion isn’t consistent with community rules.

While /c/askscience doesn’t have a rule against soliciting medical advice, I’d strongly recommend against trusting the comments from random internet strangers. Especially those without authoritative sources to back them up.

Unfortunately the only way to get a reliable answer to your question is to speak to a medical professional.

I’ll echo the other replies that the gravitational waves from black hole mergers have been detected by LIGO. In fact, the 2017 Nobel Prize in physics was awarded to members of this collaboration specifically for this feat.

We haven’t (yet) seen a pair of black holes collide using light directly, but the gravitational waves have been perfectly consistent with general relativity calculations. Here’s a video from LIGO that shows what one of these simulations looks like, for a simulation that reproduces a detected gravitational wave.

As an aside, right around the time the LIGO team was awarded the Nobel prize, they detected the collision of a pair of neutron stars. They alerted the astronomy community to the direction they saw the signal from, and within a day there were telescope observations of light from the kilonova that resulted from the collision. Ultimately various sensors recorded optical light, infrared, ultraviolet, gamma rays, and radio waves being emitted from the explosion. The hope is that someday we’ll get lucky enough to see similar photon signatures from a black hole merger!

For physics specifically, a bachelor’s degree probably won’t be enough to get a job in physics.

You might be able to get a job as a technician in a lab, but they typically will look for people with a master’s degree for those roles. With just a bachelor’s , you’d need to get your foot in the door by already having some relevant experience, which is a possibility if you get some research experience in college and pivot that into an internship or something. But it would definitely require effort and luck.

I’m not sure that’s a good comparison. The kill mechanism from a neutron bomb is the deposition of ionizing radiation in the body, but the microwave radiation is non-ionizing.

You’ve gotten some good answers explaining that heat changes the density, and therefore the index of refraction of air.

Fun fact: Schlieren Imaging allows one to photograph shockwaves by relying on the same effect. As a shockwave travels through air, it creates a region of high density, which can be imaged with this technique.