How Smooth is a Neutron Star? - Sixty Symbols
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- Опубликовано: 5 ноя 2020
- Featuring Professor Mike Merrifield from the University of Nottingham talking about neutron stars and pulsars.
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The (multi-authored) paper we discussed: arxiv.org/abs/2007.14251
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www.bradyharanblog.com
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3 pages of authors: "Smooth."
Coming from a field where papers usually have 2-3 authors, at most, that screenshot of the paper gave me a solid chuckle
If this is a significant enough finding, they're all gonna have to share the prize as well.
spiny bal is round
Everybody gets to type one letter.
Some fraction of those authors made no contribution to this particular area of research. Anybody who is working on improving any aspect of gravitational wave detection will be listed on every paper published by the LIGO-VIRGO collaboration. However, someone who is currently working on reducing noise sources or doing simulations of future interferometer configurations or developing novel search algorithms for detecting signals, etc. will generally have made no contribution to any results being published now because there's a time lag between the research being done to improve the detectors and the particular detections being made as a result of those improvements.
Who knew that neutron stars were the friction-less spherical cows this whole time.
in vacuum, don't forget the vacuum!
Dude nice
I see what you did there.
I prefer the term edgeless cube.
And you have to neglect air resistance.
"Smooth as a pulsar" should be a saying.
It is now!
It definitely should
Smooth as a babies nuertonne
As smooth as a pulsars bottom.
Smooth as a Neutron star. Pay attention. Lol.
"I'll put it on my bucket list."
"Best to put it last."
"You wouldn't enjoy it".
That's the best thing about this part of the list, no matter if you put it in the beginning, middle or end of your list, whatever the case, it will be the last for sure.
Yeah...he would have been spaghettified long before reaching the surface of a neutron star!
So where on the list are black hole and walking Mars in a T-shirt?
I like the fact , there are no bgm ,no intro music no nothing . Simple , Clean and Educative . (Yet not boring). Noiicee . Hard to pull of these kinda vids and u guys are nailing it.
Well yes, but the intro music of PBSSpaceTime is dope. Hard to pull that off as well.
It helps when the content is raw knowledge from people with tremendous expertise.
No need to package it really
@@renendell See LockPickingLawyer's videos for a similar vibe. The intro is "Hello, I'm the lock-picking lawyer, and today we're..." 2-3min videos are the norm for him.
they dont know wtf they are talking about though so it cant really be called educative. In the future their ideas will be laughed at and forgotten
@@voidremoved Bro/Sis..... Any ideas now will always be laughed at in the future . It is the mistakes what we do now would pave way for future ideas.
As long as they provide valid information to this point of time in our lives (the present) , its always educative 😇 atleast for me (My opinion) .
Cheers!Have a great weekend 😁
"...at least a Neutron Star can do stuff a Black hole is just black"
*sad Black hole noise*
Not so fast, a black hole is a private party but we’re not invited
michael perry more like a party you can never leave
@@michaelperry1210 We are invited, though. We just can't leave.
@@nielsunnerup7099 *Hotel california starts playing*
Yeah, other than breaking all physics they really do nothing much :)
Being able to measure a deviation of a hairs breadth, or the lack of a deviation in this case, at however many light years we are talking about. Now that's what I call resolution.
It still tells us nothing about anything.
@@yellow01umrella well that’s not true is it.
Yep, its out-of-this-world impressive!
Dolphin Man
Big discoveries in science are built upon tinier discoveries. Now while they try to learn more about neutronium or nuclear forces or quantum gravity they can dismiss any theory which doesn't predict this smoothness. That's the sort of science that might result in advanced materials like room temperature and room pressure superconductors or even greater technologies.
It's not a true measurement but a conclusion made by way of the speculation that if a neutron star had topography it would be detectable as gravity waves. Since the waves are not detected the inference is that the star is perfectly symmetrical, hence, smooth.
Science: "How smooth is a neutron star?"
3 pages of scientists: "yes."
These important issues they MUST make videos on. This is my favorite. My second favorite is, 'What would happen if you changed one of the universal constants?'
TheIdeanator your tax dollars at work!
@@andrewrivera4029 Much better than blowing up kids
@@cubfanmike Interesting things, probably. The universe might just not work out, or work just a bit different, like a meter (which is the length of 297 something million, maybe trillion atoms put side by side.) Being different from ours, and stars forming a bit more easily.
I dunno.
@@echoesman3439 The most scientific part of your comment was the 2 word short answer. Scientists should keep reminding themselves, it's about the search not the pontificating on RUclips
Brady nailing the "questions I was just about to ask" department again! Great video
That is horrifyingly cool . The inside of a neutron star can "slosh around" faster than the outside.
Imagine the physics going on in there
Maybe
How can the neutrons even manage to stay together at this pressure?
Ooh there are quark stars too
@@ethanbuttimer6438 they are only hypothetical for now ;)
Wouldnt the frictiin between the layers slow the neutron star down
Neutron star diameter: ~20km (2x10^4m)
Hair's width: ~100um (1x10^-4m)
Smoothness factor 1/5000000000
1kg Si sphere diameter: ~10cm (1x10^-1m)
Si atom diameter: ~0.2nm (2x10^-10m)
Smoothness factor 1/2000000000
So about the same!
That's crazy! Though keep in mind the smoothness described here is an upper bound, in reality neutron stars might be much smoother still.
What it you compare the errors? In the neutron star case, it's likely closer to the x-sigma std dev of the neutron radius, in the Si ball case, it's closer to the std dev of an Si atom, practically? Or the electron shell thickness?
@@sk8r536nb In the case of the neutron star, the error would come from the precision at which these measurements can determine an upper bound-not from the radius of the neutrons themselves.
@@Nomen_Latinum I think the Si atom diameter is the local smoothness. Since errors can accumulate, the out-of-roundness value (peak to valley on the radius) is much larger, about 50 nm. --> the neutron star wins. What do you think? See also my comment above for my calculations.
@@joachimneumann5295 In that case, you're completely right! Though keep in mind, this video is not saying a neutron star is perfectly spherical. In fact, I'd expect it to always be wider at the equator than it is at the poles (oblate spheroid). So in a sense, the out-of-roundness value of a neutron star is determined by its oblateness, not by its smoothness, making it hard to compare. The best way to compensate for this would probably be to correct for oblateness in either case, but I don't know enough about neutron stars OR silicon spheres to comment on that :)
Another related thing to keep in mind is that this paper -technically- only shows that neutron stars are radially symmetric; for all we know (and to be clear, I don't) they could have ripples or quakes going up and down between the poles in perfectly symmetrical fashion.
All that said though, it seems very likely that the neutron star is indeed the smoother object :)
Professor states an absolutely mind boggling fact
"Huh."
Yeah, had to listen to it twice to enable my brain comprehending it.
First time: What?
Second time: Whhhhuuuaaaaaat?!?!
Love this thread, I thought the same as you crucci and did the same as you Schall.
I think my brain had a short circuit when he said this, absolutely amazing.
I could listen to Prof Mike speak about a cardboard cereal box. The man is just epic. Same with Prof Copeland. Both are giants.
Love him too, he’s got a very approachable style given the subject matter.
Copeland could talk about a shite he’s has and I’d sit and listen in awe.
Yes they are all really cool professors. Who's the guy with glasses, a little more full face than this professor. I like him too.
What hw said at the ending was confusing..what ondorect effect is he talking about?? The wabes..but that's notnindriect..and the whole video he says neutron stars are perfectly smooth and their spin is perfectly symmetric but then at the end he throws in the fact that their soun is Not summetric due to magnetic fields they have..that's mind of contradictory..didnt amyoen else catch this?
Captain crunch isn't bad either
Love that you say you don't know the answer to some of the more creative questions instead of BSing! My favorite teachers did that
If you touch a neutron star, you become the neutron star lol.
Compared to a neutron star, we are basically empty space.
Even if you only had a teaspoon of neutron star, it would rip you to pieces, then plummet to the center of the earth.
@@TlalocTemporal no, it will explode because there will be not enough pressure to keep it's form
@@p3el_ -- Well assuming it didn't do that. It's a less useful metaphor if all it does is explode into nuclear radiation.
@@TlalocTemporal reality is often dissapointing
so it is the ultimate solvent
When I was younger people often mentioned the outer crust of a Neutron Star would be a thin smear of iron with little mountain ranges a millimetre high... guess that's out.
So how does this new constraint affect the notion of star-quakes in a cracking crust causing some Neutron Stars to experience timing glitches as their spin rates are altered? These are fascinating objects indeed.
Most things like these are based on commonly accepted theories, but rarely turn out to be facts after new big discoveries are made. Its safe to assume that neutron stars got so rough surface that you can sandpaper an old table in 2 nanoseconds from a billion miles away.
IDK how ive been following numberphile and computerphile for years, but only stumbled across sixty symbols a few months ago...
as a physics student this is now my favourite of your channels
dude - it's Numberphile.
@@hansmeiser32 i was a lil baked while writing the comment, fixed it
I find neutron stars more awesome (literal use) than black holes in a way because you can still sort of grasp them intuitively just on a mind blowing scale. Their density is so intense that a star quake on the surface where matter shifts less than you snapping your fingernails past each other releases such immense energy that it could absolutely devestate any plants orbiting the star...
Why would plants orbit a neutron star? We haven't come even close to demonstrating the existence of life anywhere other than earth....
@@danguee1 hahah... Because auto-incorrect 😢
Venus Fly-trap?
My favorite factoid about neutron stars is the strongest "earthquake" we ever recorded scored a 23 on the Richter scale, which is strong enough to destroy pretty much everything in a 10 light year radius. It came from a magnetar having a fit.
Black holes are boring even in a mathematically sense! There are only 3 things you can know about one: its mass, its charge, and its spin. Any two black holes that have the exact same values for those are functionally identical. Honestly, they're even less 'interesting' than a single baryonic particle (e.g., a proton or neutron), which have those same figures and at least have component quarks.
There's a fascinating, if somewhat dated novel (Dragon's Egg) about life, even intelligent life, evolving on the surface of a neutron star. Their matter doesn't run on molecular chemistry, but instead nuclear interactions. The Cheela, as they're called, mass about the same as a human, but with the local gravity of 67 billion g's, they're about the size of a sesame seed. Goes without saying, they're all terribly afraid of heights.
Watching prof Merrifield for years now, yet when he gets really into it, as a non-native, I still concentrate like on nothing else. Love these vids, keep them coming. :))
Some mistakes and points of interest:
0:55 Not all pulsars are neutron stars. Some pulsars can be white dwarfs.
0:59 We can see non-pulsating neutron stars as well. Many have been identified.
1:41 The fastest rotating pulsar we know of spins around 716 times per second. Not even close to a thousand.
1:45 Maybe I'm being pedantic here but "several times mass" implies more than 2x. The Tolmann-Oppenheimer-Volkoff limit is only for non-rotating neutron stars. That range is 2 to 3 solar masses. The most massive known neutron star with an accurately measured mass is 2.14 solar masses.
5:13 Its not nuclear forces that are pulling everything to a smooth symmetrical shape. Its gravity. Neutron degeneracy pressure and repulsive strong nuclear force resist gravity from imploding the star into a black hole (or a more exotic type of matter)
5:50 Yes it is rounder than what humans can make. The roundest man-made object is Heason Technology 5-axis manipulator. Its a silicon ball of exactly 1kg, 94mm diameter with less than 50 nanometer roundness delta. A neutron star of 20km diameter with a roundness delta of 50 micrometers (the width of a human hair) is two orders of magnitude smoother than that silicon ball if we assume the silicon ball roundness delta is 40 nanometers.
nice ! thanks for all that
You missed a fullstop.
There is a reason he is a DR and you're sat in your chair being a RUclips Astronomer
@@bvbinsane1vanity Someone sounds upset!
It may be rounder but question is the absolute smoothness
The amount of energy these things have is beyond comprehension.
Absolutely mind boggling.
I just comprehended it! Wuz easy dude....im not impressed at all.
@@karlandersson4350 ok Galactus🧠
"Is it cold? Is it hard?"
No... the real question is:
"What does it taste like?"
It tastes like Neutrons, duh.
So what if I pick up a neutron star metiorite ? ...I'd be cooked like plasma ,right ?
@@tomgucwa7319 I think the entire planet would be cooked
Yellow of course.
Probably like a pulsar.
"A hair's breadth" considering that mass density of a neutron star is extremely dense, doesn't surprise me that a "hair's breadth" amount would create that phenomenon.
He should've mentioned that a hair's breadth more in any region would contain as much mass as the moon.
@@davidschneide5422 It would be wrong though. The mass of a moon in neutron star matter would be about 100 metres across.
@@Parasmunt it really depends on the numbers you use I guess. I played a bit with them (not too math savy though) and used 1*10^9kg/m³ for the mass of the outer layer of the neutron star, there, our moon (7,346*10^22kg) would occupy exactly 1km³, which is way way more than 100 meters across.
for the hair thing, I calculated 7,5*10^-9kg, so 7,5 microgram, using a hair with a width of 100 mircometer and a length of 10cm. Went with V2*ρ1/V1=ρ2, not sure if right. V2 being the volume of the hair, ρ1 the density of the neutron star on surface level, V1 the volume of the neutron star.
Correct me if I'm wrong please, it might be, just getting back into this stuff.
@@Parasmunt but added to an entire neutron star already would make a very small addition to the overall diameter
@@NoSkillsNoFun For the hair, I don't think you need to divide the whole thing by the volume of the neutron star. We just want to know how much the volume of a hair weighs if it had the density of a neutron star which I think should just be V2*p1. I tried this and with a volume of the hair of 0.0000000007854m^3 (0.0001m diameter and 0.1m length) I got a weight of 785.4g using the outer layer density you gave and that does seems more correct. Ben from Applied Science made a video about a DIY microgram scale and in that video he said his eyelash weighed in at around 35-40 micrograms.
Edit: Also for the volume of the moon in neutron star density. Rearranging the equation for density gives volume = mass/density. Using this, the volume of the moon at neutron star density would be V= (7,346*10^22kg) / (1*10^9kg/m³) = 7.346*10^16m^3 or in kilometers 73,460,000 km^3. Thats pretty dang tiny when you consider the moon's volume is actually 21.9*10^9 km^3. It's only 0.33% the size! A sphere of that volume would be about 520km across.
The love and dedication from Mike for astronomy and Physics is inspiring, thanks for the videos :)
That concept is so hard to imagine. I’m jealous of the physicist that can grasp it mathematically. The amazing smoothness.
They did create the concepts and have to present them as facts, doesnt mean they are. Lots of todays astrophysics are partially based on widely accepted theories, the room for error is immense. We live in a dark age, we base our understanding of the creation of the universe on obvious lies like inflation theory, our understanding of QM is that it is random and “mysterious, nonsensical”, clear misconceptions but we lack the undiscovered sciences that are required to explain it. Scientists otoh seem to be happy with the giant holes in knowledge.
One thing we all have to agree on is there is something there sitting in that little piece of space. And our primitive understanding with what knowledge we have so far of matter is that it fits these theories that those physicists and mathematicians believe. We are literally communicating right know with devices that have been developed with that knowledge. Basically, if it walks like a duck and quacks like a duck it probably a duck.
Great start of the weekend, thanks guys!
I'm a big fan of the more extended questions format. Great video.
Professor Merrifield explaining that we would be able to detect if an object 20km across, weighing several times more than our sun, many light years distant, were deformed by a hair's width.
Brady: "Huh."
4:36
The "This 1200+ people helped us not detect the gravitational wawes. Here's what we think about it." paper.
Great questions from Brady and wonderfully explained by Professor Merrifield
Really really love this channel. Thank you so much for sharing your professional insights with us!
With the explanation in the intro, am I correct in understanding that a pulsar is a matter of perspective? In as much as *my* position in the universe relative to a neutron star determines whether it’s a pulsar or not?
1:06 if the magnetic field axis is *not* aligned with the rotation axis, it's a pulsar.
(Imagine if the magnetic field axis *_was_* aligned with the rotation axis, the neutron star wouldn't be sweeping its beams across the universe, they'd just point without sweeping.)
As for our perspective, a neutron star may be a pulsar, but if it's not sweeping across us, we wouldn't know it's a pulsar.
We have reason to believe that the vast majority of neutron stars don't have aligned magnetic fields and so almost every neutron star is a pulsar to at least some observer, the problem is until we become space-faring, we cannot confirm which if any neutron stars don't pulse and which are just not aligned with us. Until then, we might as well only call the ones we can absolutely confirm as pulsars "pulsars" and everything else just neutron stars.
if a neutron star pulses in the intergalactic medium, but no on is around to see it, is it a pulsar?
@@ObjectsInMotion
I agree, was the same with rotating black holes, today science presume all black holes rotate, tens of years ago they were more uncertain about it.
That's smooth!)
Ok, jokes aside, this is really a great episode and it's mind bogging how "gravitational waves astronomy" allows us to measure how smooth an object is hundreds of light years away with such precision.
Thanks for this video and for doing this remotely. 🙏
I really appreciate your presentations...excellent, entertaining, and spot on info from the professors I so respect and look up to in awe.
Something about an astrophysicist saying "I don't know" is really humbling.
Yes. When he said that I was kinda disappointed, however they need to say it more instead of acting like they have all the answers. I rather be disappointed than lead astray with silly theories.
@@XavierMathewsEntertainment Every time an expert says "I don't know" there's an opportunity for a writer or poet to imagine something new.
That's because they actually don't
This is why Science (capital S) endures and religious dogma does not. The former admits not knowing everything while searching for ultimate truths. The latter claims to know all ultimate truths while never seeking enlightenment.
I remember in a course I took covering an introduction to astrophysics we did a group project on Magnetars (neutron stars with magnetic fields that are completely bonkers), and I read a little bit about the space surrounding these things and the theorized matter inside the crust. It would be very interesting to see a take on these things, as the last I read was some theory that the pressure inside the crust is enough to cause a high-temperature Bose-Enstein condensate of sorts, which is wild.
And then all the girls in your area wanted to sleep with you. Thats awesome!
Mike is a great professor and explains things so elegantly. Thank you very much for these videos. Mike you're doing a great job, really enjoy how you see the universe
Enjoyed that chat. Thanks gentlemen.
Marvel: "Avengers: Infinity War is the greatest crossover event in history"
Scientists:
Scientists : Hold my research paper...
I always wanted to know about Gravitational-wave Constraints on the equatorial ellipticity of millisecond pulsars!
Me too! Was the first thing I thought of this morning
😂😂💯👍🏾
Spectacular subject. It’s great to hear ligo and vergo doing even more interesting observations.
enjoyed this discussion immensely
This was a cool read! I've got a couple of mentors which currently work with LIGO. One of them specifically work with continuous gravitational waves (like those from millisecond pulsars).
The fact that we have a chance to detect changes in spacetime caused by a lop-sided spinning ball with more than the mass of the sun is seriously mind blowing.
So many authors it will be legit to write FIRST in that research paper.
:o)
lol
I believe the LIGO-VIRGO collaboration lists publication authors alphabetically for all-collaboration papers like this, so name order is not hierarchical.
I live how many times Professor Mike M says 'we don't know' . Neutron stars are amazing!
Very clever questions! Wonderful video!
Fun fact: The earth is actually smoother than a billiard ball. In size adjusted terms of course.
And Kansas IS flatter than a pancake..
Not true, OP. Just another urban myth
@@sillysausage4549 Tolerance of a regulation billiard ball is +/- 0.005 inches which on scale of Earth would be +/- 28 km. Marianas Trench is -11 km and Mt Everest is +8.85 km. Depending on how you define the zero level, the equatorial bulge (42.6km) will either fit within the 56 km tolerance band (if you define the zero level in the middle of it) or take the Earth out of round. Either way, Earth as smooth or smoother as a billiard ball, but not necessarily as round.
@@brianoconnor4269 Earth is very smooth, just a very smooth potato.
I remember a colleague said a person gave him a ride to place and he included that guy's name in the paper too
The audio is excellent Proffesor Merrifield.
Thank you
Edit: would love a series on non black hole stellar remnants, magnetars, strange stars, quarkstars etc
Thanks, guys. Very fun and interesting. Great job. More, please.
I'm gonna reference those 3 pages of authors as blah et al.
al is like the best scientist ever because his name is referenced on almost every paper - zefrank
What about "quakes" on neuron stars? Does the roundness change briefly and then settle back to perfectly round?
The oblateness can change, especially as the star's spin slows. The star remains smooth ans symmetrical but becomes more spherical and less flattened.
I remembered some numbers from a couple of Veritasium videos that explained how the smoothest object we have made, when scaled up to the size of the earth, would have about 14 meters between the tallest mountain and the deepest valley. And only 5 millimetres on a neutron star.
So if we scaled up a neutron star to be the size of the earth: ~6,400km(earth radius) / ~10km(neutron star radius) = 640
So a neutron star is about 640 times smaller than the earth.
So we can multiply the tallest mountain height on a neutron star(5mm) to get the height of the tallest mountain if the neutron star was scaled up to the size of earth(640x): 0.005*640=3.2m
This means that a neutron star is about 4 times smoother than the roundest object we have ever made. (14 / 3.2 = 4.375m) and about 5000 times rounder than the earth itself.
That's quite impressive that we can get so close to matching the smoothness of such a massive stellar object.
*note: I am not a mathematician, so feel free to do your own calculations as I could be way out here.
Professor Merrifield brightness shine with this very smooth explanation.
STROKE THE STARS BRADY! FOLLOW YOUR DREAMS!
Neutron Stars Declared Unstrokable by Eminent Professor!
Really interesting stuff. Thanks 👍
Thanks for the upload.
I bet we could use this smoothness as some sort of standard for measurement.
Here we are selling the smoothest silk! Try our 0.0012 pulsars silk! Or our elite silk, 0.0025 pulsars!
Oh dang getting interference from the actual Insturments’ electricity that’s wild
Happens quite often, 60Hz noise or signal is almost always linked to the power grid somehow. As an undergrad, I was working on a project where I was monitoring some detector using an oscilloscope. The signal I was getting had a 60Hz noise component which started at around 9am, stopped at 5pm, and took an hour break for lunch. I don't know what the source was, but obviously some human operated equipment in a nearby room :-)
Yeah, if you ever look at the raw output of an antenna+amplifier in most frequency ranges you'll find that our world is full of electrical noise. 50-60 Hz is the worst because that's radiated by power lines, but you can get 120 Hz directly from lights, and some fluorescent lights also have switching frequencies around 30 kHz (discovered that for myself recently when we thought a new instrument we were building was broken, but I figured out the noise went away when we turned off the lights). High frequency electronics can also be sensitive to local capacitance, i.e. you can affect them just by waving your hands around near them or wiggling some wires around.
Most astrophysics observations have to take this into account along with many other types of noise.
"I'll put it on my bucket list."
"Best to put it last."
another great video! I love all the graphics
Great questions. Great answers. Enjoyed that thanks!👍
5:48 ZEISS Group made ASML's flat mirrors for EUV lithography. Quote: *"Scale one of these mirrors to the size of Germany, and the biggest bump that you'd find on their surface is just 1 millimeter high"*
So like, really rough compared to a Neutron star. (Actually, it's impressive that it is within a couple of orders of magnitude of a Neutron star; Very cool).
I would love to know how the angular momentum is conserved when something slows down due to emitting gravitational waves. Anybody know?
You're right! The gravitational waves themselves carry angular momentum away from the system!
@@KyleGersbach Newtonian physics just can't catch a break.
Hmmm
Its not conserved in open systems.
Theres no conservation of energy/momentum in GR. Theres a local version of it though...
Here i am back to watching another sixty symbols vid but this time i am a University of Nottingham Students myself!!!
Really enjoy all of these videos!
Cheers.
The scientist has mastered the art of talking really quickly whilst somehow not being completely exhausting to listen to, at least for an old bloke like me. Even as l write this l can still remember a lot of details about what he said. Nice.
That rotation looks weird though
Edit: now I remember the axis about which it rotates and the light beam is not coinciding,
Wouldn't the Frame Dragging from such pulsars still emit Gravitation Waves?
That's a much smaller effect and why we're not currently looking for rotating black holes this way.
such a great concept for a video!
So back in your Tardis professor... greetings and thanks for your explanation
the heartbeat of the universe
So do gravitational waves have angular momentum?
Yes they do!
This was a rad video!
WOW, I love you guys, great show. Kevin from sunny Mexico.
We do need a LIGO in outer space!!
The amount of clean readings will be huge! And a good companion to JWST!!
We're working on that right now!
It's called the Laser Interferometer Space Antenna (LISA). It's current schedule puts it in space in 2034
@@KyleGersbach Yooo. That is awesome. I'm gonna put a bottle of champagne in my fridge right now!
Absolutely. Space LIGO would be amazing.
Oh man waiting for it .. 2 at diff axis, 100s of km apart. We can probably detect anything and also find whole new things happening in the universe. Hope the scientific community prioritize this
@@KyleGersbach wow, 2034. I thought we were much closer after the successful LISA Pathfinder mission.
Do you have more details on what exactly makes it take 15 years to build these spacecraft? JWST has taken forever because the incredibly complicated unfolding mechanism. By comparison LISA seems to be a relatively simple experiment. The tolerances to make the interferometry work must be absolutely tiny...
Let me guess: Very.
Almost
very smooth is an understatement
If objects are rough because their molecular structure supports hills, then you have to imagine what an object would be like when the forces applied to it omnidirectionally are so strong that it breaks down not just the molecular structure, but the atomic structure as well.
These animations are beautiful.
Tres cool, thank you
How smooth is a black hole?
Infinitely smooth.
no equatorial buldging when rotating so fast?
That does happen but it's still symmetrical
I don't think so. The gravitational pull is so strong that it's probably gonna be a perfect sphere. But I'm not sure.
If it is rotating 1000 times a second then the equator is moving at 20% the speed of light.
Utterly fascinating, what an interesting man that Professor is and i marvel at how well he explains this science. Would have liked them to discuss Starquakes.
A couple of questions:
1) Wouldn't the insane magnetic fields around these things be expected to interact with the matter in the neutron star if there was any kind of charge at all?
2) If there isn't any charge at all, why is it producing a magnetic field?
3) shouldn't we see things slamming into neutron stars with some frequency? Even if they tend to clear out their immediate environment at birth, every once in a while they should run across some kind of debris that would slam into the surface at a significant fraction of the speed of light. Granted, it probably wouldn't come close to the mass of a neutron star, but that much momentum ought to show as something, shouldn't it? A temporary ripple of asymmetry?
Those guys can measure a spinning ball the size of a city, lightyears away by the precision of a human hair, yet I manage to buy way to much floor because I am to dump to measure the room.
But they haven't measured the size of the sphere to that precision! They've figured out that, however big it actually is, it's within a hair's breadth of being a perfect sphere.
We bought too few tiles to finish a shower stall. And when we went back for more it was discontinued and unavailable. Having too much is better. :-)
How about energy loss by frame dragging of space due to the immense gravity and the neutron star's rotation?
Does that radiate energy? I've never thought of it. I just think of frame dragging as gravity doing its thing, but that could be completely wrong.
@@volbla I think it uses up some energy from the neutron star's rotation, but I see no reason for radiation by frame dragging space near the star. I can't prove if and how much energy this would use up, unfortunately.
To my knowledge there is no gravitational wave emission associated with frame dragging.
Professor Mike Merrifield mentions in the video that gravitational waves are associated with change of the gravitationalf field that is noticable at any distance to the source. Example of a violent event without emission of gravitational wave: perfectly symmetric implosion. While that is a very violent event, it does not change - at distance to the source - the magnitude or direction of the source's gravitational field. Hence no emission of any gravitational wave. Frame dragging does have chirality, but at any distance to the source the magnitude and direction of the gravitational effect is free from acceleration.
The LIGO interferemeter detects a change when there is a transient expansion/shrinking of one or both of the arms of the interferometer. The frame dragging of a spinning gravitational mass isn't transient, it's constant.
I'm thinking of it like this: A massive body just sitting still in space has a gravitational field, because that's what mass does. Having a gravitational field doesn't cost any energy.
Similarly, a spinning body also has frame dragging, and that's simply what the gravitational field of a spinning body looks like. The only way that would cost energy is if spacetime inherently had something akin to friction.
Does spacetime have something like friction? I have no idea. Never heard of it ¯\(ツ)/¯
@@cleon_teunissen Since physics isn't quite my playing ground, I try reasonable "kitchen school" argumentation. I'm not looking at generation of gravitational waves in my initial question. A (unlikely to exist) non-rotating massive body does its gravitational thing to space: I assume this doesn't consume energy from the massive body, can't explain why.
Frame dragging having chirality is an interesting point. I don't think frame dragging propagates any gravitational waves, but again can't explain if and why not. Generating gravitational waves must consume energy, simply because this is what is observed, well rather modelled, by the gravitational observatories.
Still I can't wrap my head around that frame dragging by rotating massive bodies should come "for free"
This a video that tickles the brain exceptionally well.
Thank you.
The Earth is smoother (but not as round) than a billiard ball.
The earth definitely not Smooth, we have 30,000ft mountain's and deep sea trenches miles deep.
@@voodoojedizin4353 pay attention: I wrote smoothER. Which means that it's not perfectly smooth.
But it IS very smooth. Extremely smooth, in fact.
How can the Earth be considered smooth when it has 2 mile deep oceans and 6 mile high mountains, you ask? *SCALE,* that's how.
The Earth's (average) radius is *3960 Freedom Units.* A six mile high mountain is only 1.5% of 1% of the radius of the Earth.
That's very smooth.
@@voodoojedizin4353 I think what is being suggested (not sure it is true) is that compared to the radius/circumference the deviations of altitude on Earth are proportional smaller than what occurs on a billiard ball. If so, the statement would be true. Likely the relevant information to make a conclusion would be online.
@@voodoojedizin4353 watch vsauce
@@M.-.D that's exactly right.
neutrons are electrically neutral so where does the magnetic field come from?
A Neutron has no electric charge, but it has a magnetic moment.
At about 7:00 there's a cross section of the neutron star, there are charge particles in the interior, motion of this material can produce a global magnetic field.
Same as asking "If a current carrying wire is neutral, where does its magnetic field come from?"
insightful!
I think it's true to say that in order for a rotating body or system to radiate gravitational waves its gravitational field must have at least a quadrupole moment. So an axisymmetric body won't radiate, as stated here.
I would assume most of the authors have no idea this paper exists.
What creates the magnetic field, if they’re made of Neutrons?
*All Pulsars are Neutron Stars, but not all Neutron Stars are Pulsars. What’s creating the difference?*
Edit: Energetic Electrons in the atmosphere???
Someone answer this plz
As far as my google-fu tells me, they aren't completely made of neutrons. They have some amount of protons and electrons and these are what causes the magnetic fields
Neutrons are made of charged quarks, so a neutron has a magnetic moment, even though its overall electric charge is zero.
Neutron stars have several layers beyond just being blob of neutrons, comprised of; iron nuclei, electron gas, and a mixture of superfluid neutrons and electrons - I'm not sure of the exact composition as it's not my field, but the short answer is that it's a very complicated mix of condensed matter.
Neutrons have a magnetic dipole moment from the charged quarks they are made of
Exactly that feel is an important component like how the surface looks like etc feels like
That hair's breadth fact blew my mind
5:40 _"Smoother than a billiard ball."_
Planet Earth is smoother than a billiard ball.
@Hose2wAcKiEr , Earth's radius is 6,400km, with mountains & trenches being ±9km.
That's smoother than a billiard ball.
That’s a misconception based on a misinterpretation of billiard ball regulations. Vsauce explains it in the video “How much of the earth can you see at once.”
The billiard ball is actually smoother
papers with that many names would be why the Nobel prize has the rules it does.
Some fraction of those authors made no contribution to this particular area of research. Anybody who is working on improving any aspect of gravitational wave detection will be listed on every paper published by the LIGO-VIRGO collaboration. However, someone who is currently working on reducing noise sources or doing simulations of future interferometer configurations or developing novel search algorithms for detecting signals, etc. will generally have made no contribution to any results being published now because there's a time lag between the research being done to improve the detectors and the particular detections being made as a result of those improvements. Many who actually contributed to producing the latest results will also have left the collaboration to work elsewhere.
In my opinion, whenever a Nobel prize candidate is chosen, they should in turn be required to nominate others who they think directly contributed to the research that they are being awarded the prize for. Limiting the number of recipients to just three is unfair.
Can they not award the Nobel Prize to the LIGO-VIRGO team as a single entity rather than individuals? They've done it for the Peace Prize I believe.
I have been fascinated by neutron stars, magnetars and pulsars for years, absolutely amazing objects 👍
Liked and shared. Thanks for posting.
Wow, it never occurred to me that a perfectly symmetrical object would NOT emit gravitational waves.
It would be like a "no-friction" (very loosely used word!) interaction with spacetme. Ofcourse it would not emit. Fascinating.
He is saying It could be radiating gws but we may not be able to detect it. It does radiate lots of electromagnetic stuff though.
It's almost the same reason why a charged particle moving at a constant velocity doesn't emit radiation, only when it accelerates is light emitted.