Astrophysicists detect the strongest magnetic field in the universe | Hacker News Reader

Astrophysicists detect the strongest magnetic field in the universe

nanowerk.com

97 pointsblnqr37 comments

Magnetars are even more mindblowing than blackholes, in my opinion.

Here is an excerpt from the Wikipedia article on Magnetars, to blow your mind as well:

"X-ray photons readily split in two or merge. The vacuum itself is polarized, becoming strongly birefringent, like a calcite crystal. Atoms are deformed into long cylinders thinner than the quantum-relativistic de Broglie wavelength of an electron." In a field of about 10^5 Tesla atomic orbitals deform into rod shapes. At 10^10 Tesla, a hydrogen atom becomes a spindle 200 times narrower than its normal diameter., from https://en.wikipedia.org/wiki/Magnetar

Edit:

"Die Massendichte, die einem derartigen Magnetfeld über seine Energiedichte in Kombination mit der Äquivalenz von Masse und Energie gemäß E = m c^2 zugeordnet werden kann, liegt im Bereich einiger Dutzend Kilogramm pro Kubikmillimeter (kg/mm3)", from german Wikipedia, https://de.wikipedia.org/wiki/Magnetar#Entstehung

says that the mass density (via energy-mass equivalence) of such strong magnetic fields might be dozens of kilograms per cubic millimeter (kg/mm^3).

Mind. Blown.

How do those rod-shaped atoms, like hydrogen, interact with other hydrogens or other atoms? Can chemical reactions still even happen in the traditional sense?

Layman here.

Most classes of stars are already hot enough that molecules are torn apart. The atoms are in a gas or plasma state. Pairs of atoms will pass through transient states that could be classed as “molecules” but they’re very short-lived. Electrons—a key part of chemical reactions—flow freely like in metal.

Hydrogen atoms are just a single proton with some number of neutrons. I’m not sure if the proton itself is stretched (Is a gluon a particle like a proton is a particle??), or if the EM field around the proton is so influenced that electrons move around it like it’s a rod/cylinder.

Depends, chemistry looks very differently simply because in such environments it is better to think of an electron gas that moves in a magnetic field, and is slightly perturbed by the presence of nuclei, rather than thinking of electrons being bound in atoms and being slightly perturbed by a magnetic field.

So you certainly have to recalculate all your reaction rates compared to laboratory conditions, and my guess would be, that in general the chemistry should look a lot more than reactions in plasmas, rather than normal (nicely stable) chemistry.

The temperature is expected to remain above plasma temperatures even if a neutron star could cool for a billion years, so presumably normal chemistry couldn’t occur.

https://astronomy.stackexchange.com/questions/14387/what-hap...

The coldest neutron star detected “T < 42,000 Kelvin” : https://arxiv.org/abs/1901.07998

Disclaimer: I am not an astrophysicist.

“a significance level of > 20σ”

Insane! Clearly that doesn’t include the uncertainty in our understanding of physics or neutron stars.

Edit: I tried to work out the % that 20σ is, but it is so mind bogglingly small that there should be a law against using such an insane number in any serious context.

Each tail is bounded above by e^(x^2/2) / (x sqrt(2 pi)). Take logs and you get (x^2 / 2) - log(x) - log(2 pi)/2. Calculate that out and you get to about 1.44 * 10^85. You can double that for 2 tails. But it is still an impressively small number.

This is almost certainly not the strongest in the uninverse based on the sample size of our observations right?

This is the strongest we have observed. Still really fascinating.

My thoughts exactly. The title should be updated to reflect this (I was expecting some sort of theoretical limit to a magnetic field).

This has been a pet peeve of mine forever. I’ve just given up on it and mentally inject ‘known’ as necessary to avoid the cortisol.

In cosmology, "in the known universe" is always implicit. If the universe turns out to be flat and infinite, then whatever unlikely thing you can think of happens an infinite number of times in any infinitely small time period you care to mention.

Somewhere, in the field of infinity, a whale materialized above a Three Stooges convention and landed on a newly sentient petunia, an infinite number of times since you started reading this sentence.

Perhaps not in the known universe, sure, but somewhere. So "known" is always the implicit qualifier, but it'd be a pain in the neck to diligently write "known universe" every single time when the people familiar enough with the material to note the distinction also understand that's what you meant anyway.

For one, I appreciate this perspective, I was not aware of that.

On the other hand this feels unconvincing to me. The language of science and physics is already obtuse and overly wordy, that's what seperates it from the noise of everyone else talking, because it trades precision for brevity and so it feels reliable . So there are infinite places to draw that line in the sand. Why do we stop right there? Why don't we just say what we mean instead of piling up a bunch of words into a statement which is objectively false without all the context.

Because jargon is extremely helpful for communicating ideas quickly between experts, and it's a pain to have to switch to entirely non-jargon when communicating with anyone else.

Well, it’s because the more precise words don’t really provide more information. And honestly, we do this exact thing constantly in everyday life without thinking of it as confusing.

For example, “Usain Bolt is the fastest man alive”. Sure, that we know of. There might be some kid in Chile that’s .05s faster, but we’ll never know because his life circumstances don’t bring him to our attention. “The Bugatti Chiron is the fastest car anywhere”... except for that speed demon tearing up the tracks in orbit around Alpha Centauri. “Stephen Hawking is the smartest guy”, if it weren’t for that absolute genius herding goats in Siberia who didn’t get to go to school and has the local reputation as the weird kid arranging the livestock in novel patterns. “Tuna is the most delicious fish” because no one’s thought to make sashimi of that weird looking thing we dragged up from the Mariana Trench.

In all of those cases, there’s an unspoken “...that we know of”. Even if you believe that each of those cases is the fastest, smartest, or otherwise best, you have to concede that there may be another faster, smarter, or better elsewhere that we haven’t discovered yet.

So why pick on cosmologists? It’s literally impossible to declare anything to be “the most $X in the universe”, first because the universe has an infinite amount of stuff we’ll never be able to see, and second because we haven’t even remotely finished cataloging a zillionth of the stuff we can actually look at. Picking on them for not inserting a redundant “known” in every sentence, when it doesn’t add information to their statement and would just be adding filler, isn’t fair.

If you define man as human and we have open events to let people determine who's fastest, it's totaly reasonable to assume he is actuality the fastest man alive. On the other hand this isn't packaged as some sort of scientific claim and has a lower burden of proof.

I don't think anyone beyond an anecdotal context is explicitly claiming hawking was the smartest and either way, it's not measurable and so is inherently subjective.

Delicious, subjective opinion.

All of these are reasonable statements, it's clear up front that they are subjective statements of opinion or their scopes keep them within validity.

Saying a magnetic field is the strongest in the universe based on a measurement in defined units is drastically different type of claim than the ones you mentioned. In this case it's an invalid claim so we should probably stop saying it.

"Anything can happen in infinity" only holds if anything can indeed happen, but "doesn't" due to vanishingly small probabilities. Infinite trials still have bounded results. I'm not sure there's a theoretical mechanism that can randomly materialize whales, no matter the unlikelihood!

There is, it's called quantum fluctuation. It is VERY unlikely a whole whale could materialise this way in a volume of known universe, but not impossible.

That is what I heard as well, but I still don't grasp it. Infinities have different sizes too, right? I imagine something like this: the probability of subatomic particle of a functional whale appearing due to quantum fluctuation drops faster and faster with each additional particle, while the additional space of infinite universe increases only with d3. I am no mathematician or physicist though.

I think the intuition you need here is that while the size of the whale is bounded, the size of the infinite universe is not.(1) Thus the argument doesn't work, because the "faster and faster with each additional particle" assumption isn't met.

OTOH, your argument is a good one if we're talking about things like the entire infinite universe undergoing some transformation, provided that the probability of that thing happening somehow diminishes over time.

1) This is by far the best sentence I've ever written on Hacker News. So thank you! :)

That was a very good sentence.

> ~1 billion Tesla

Magnetars supposedly have up to 10¹¹ tesla. But I guess the evidence for that is more indirect.

I assumed it'd be on earth like the hottest temperature in the Universe.

> which is tens of millions of times stronger than what can be generated in Earth laboratories.

How hard is this to achieve? Billion $ or impossible?

Not sure, but Wiki says labs get higher?

https://en.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_...

Probably impossible without damaging the earth. The article talks about the magnetic force crushing particles electron fields to be flat or spindle; I would imagine generating a field like that anywhere on Earth would have a chance of flattening the magnetic core of our planet into a disk.

On the funny side, the flat earthers would finally be right.

OK, ELI5: Why should a neutron star have a strong magnetic field?

The same reason earth or the sun have a magnetic field. But the collapse of the star's core compresses the dynamo into a much smaller volume and speeds up the rotation due to conservation of angular momentum, thus making it more powerful.

https://en.wikipedia.org/wiki/Solar_dynamo

But that requires an electrically conducting fluid. Neutrons aren't electrically conducting, are they?

At pressures neutron stars deal with, the laws of know physics are more like vague suggestions.

Meaning that, for example, the neutrons could dissolve into just a sea of quarks, and then it's a charged fluid? OK, I could see that.

Neutron stars don't entirely consist of neutron soup. It's more of a mix which gets gradually more neutron rich towards the core.

https://en.wikipedia.org/wiki/Neutron_star#Structure

I think the theory is that there is enough proton degenerate matter to form a superfluid and hold a magnetic field, even if the majority of the star's matter is neutrons.

At their surface, and possibly internally, the neutronium likely breaks down, if only briefly, giving protons and electrons.

Voila, spinning charges.

Current models indicate that matter at the surface of a neutron star is composed of ordinary atomic nuclei crushed into a solid lattice with a sea of electrons flowing through the gaps between them.

https://en.wikipedia.org/wiki/Neutron_star#Structure

Neutrons do have magnetic moment after all. [1] says it's about 1000 times weaker than electron, so...no idea how much it contributes to the neutron star's field as compared to degenerate electron matter crust (which is very conductive kind of fluid).

[1] https://en.wikipedia.org/wiki/Neutron_magnetic_moment

Sort of related—Tom Scott did a survey to determine “The Best Thing”: https://youtu.be/ALy6e7GbDRQ

The second runner up is the Earth’s magnetic field.

He makes fun of his audience for ranking it that high, but planetary magnetic fields are no joke.

hell of a MRI they got over there. The jealously is real.

interesting

Let's not forget that this neutron star is measured at 5.8 kiloparsec distance from earth which is 18,917.1 light years.

Even if observable electromagnetic radiation was traveling at the speed of light, which most is not, we are looking at ancient history, because once this EM reaches earth we are studying phenomena that occurred >189 centuries ago.

We don't have a way to know if this star is even still there.

Everything studied in astronomy at significant light years distance is ancient phenomena, we are just seeing it/sensing it/evaluating it now.

The concept of “still there” in time is not very meaningful for cosmology. All of our observations are in ~space-time~ not just space or time.

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