Agreed!

6:18 I think

Wow, thank you!

@@frasercain I feel I binged like 10 years straight in the last 2 weeks or so. :D I'm totally blown away by the quality of communication. I am also inspired to look for opportunities in the industry as a web/cloud developer, as well as a photographer with astro aspirations.

That's amazing. There should be a lot of collaboration opportunities. So much of astronomy is programming and databases these days.

I'm hoping the image artifacts I'm seeing are the result of Webb's hexagonal mirrors, otherwise I know a good doctor for you to call.

If nothing is moving it would mean there are no massive bodies. If, however, you have a collection of massive bodies then that causes motion due to gravity.

@@tonywells6990 In relativity, why does gravity cause things to move? My understanding is that it just alters their movement to follow curved lines of spacetime. The reason this works is that everything is in motion. RJ's question was what happens if you could somehow remove that motion from the universe.

@@Beldizar If you stopped everything moving, for example all the planets and moons in our solar system, then the moons would fall towards the planets, and the planets towards the Sun. Gravity still exists. Over an entire galaxy it would cause everything to fall inwards and eventually you would have new orbits between stars, collapsing molecular clouds and a lot of new star formation. After about a hundred million years (typical crossing time of a galaxy) you would end up with the galaxy reforming itself, most likely into an elliptical galaxy from all the random movements of stars and chaotic new orbits.

@@tonywells6990 You aren't understanding the question. You are thinking of gravity as a force, and if it is a force, and everything stops moving, it starts moving again and falls towards everything else. The intent of RJ's question, I believe, is considering gravity, not as a force, but as curvature of spacetime which guides motion, rather than a force which causes motion. If warped space time only guides motion, and is not a force which creations motion, then if everything is stopped, then maybe gravity wouldn't be able to cause anything to fall. I don't know where I come down on the answer on this, but it is important to understand the question, and not just brush it off as "gravity is a force, everything still falls."

@@busimagen You know, that might be the answer. I think RJ's question had more legs than Fraser gave it in his answer. I'm not trying to answer RJ's question here, just clarify it.

Sounds good. But definitely ask your questions if you've got them

Thanks for watching!

"Isn't it magical that a black hole can pass through a region of space-time and the space-time just returns to its normal behavior once the black hole has gone away." Err - no, this is not magical?!? The same happens when a star or a planet moves: As long it's there, spacetime is curved; when it moves away, spacetime in the same region is flat again. "As they moved through space, they left behind some change in the value of the graviatational field. Could this explain dark matter?" Interesting idea, but I don't see how that would reproduce the observed distribution of dark matter in a galaxy.

​@bjornfeuerbacher5514 Right. What I am saying is that maybe black holes are somewhat different from planets or stars. I am speculating that when a planet or a star moves away, the gravitational field and all the other fields go back to behaving as they did before the planet or star passed through, but maybe the behavior of the fields is a little bit affected when a black hole passes because something was done to spacetime behind the horizon. Anyways, I am operating in the realm of science fiction. Thanks!

Zzzaap.

No, that would be considered a waste of telescope time. The telescope has a limited lifespan and if a proposal for an observation doesn’t teach us anything new or doesn’t disprove something, it won’t get any telescope time. Even if it was just a short exposure every day, it would use up a considerable amount of propellant Plus, there are a bunch of other telescopes that could take a timelapse of something that bright.

Not sure anything moves quickly enough there to see movement. The Crab nebula on the other hand has quick enough movement to see over the years.

The movement could already be made by the images that have been taken over the years IF it moves fast enough to see in this extremely short time span

Betelgeuse is probably surprisingly stable because it possible swallowed a white dwarf. Hence there's a massive inward pull. It's definitely an outlyer

@@Roguescienceguy What has "it swallowed a white dwarf" to do with "there is a massive inward pull"?

@@bjornfeuerbacher5514 well, when you look at Betelgeuse it is like it is constantly nova'ing(if that is even a word😅) but with the extra gravity from the white dwarf inside it doesn't quite happen

@@Roguescienceguy "it is like it is constantly nova'ing" Err - no? A nova means that on the surface of a white dwarf, a thermonuclear reaction happens and hydrogen is "burnt" which was accreted from a companion star. That is nothing like what happens at Betelgeuse. Did you perhaps mean a supernova instead of a nova? If yes, then that's wrong, too. A supernova means that a star explodes. But Betelgeuse is not constantly exploding. "but with the extra gravity from the white dwarf inside it doesn't quite happen" ??? Sorry, I can't follow your logic at all. Extra gravity does not stop a star from going nova - it's more the other way round: when a white dwarf has more gravity, it can accrete more matter from a companion star and hence _more_ easily can go nova. The same is true for supernova: A star with more mass will have a supernova explosion _earlier_ than a star with less mass, not later. Additionally, even if Betelgeuse swallowed a white dwarf, that did not increase its mass by much. Betelgeuse has a total mass of at least 16.5 solar masses; a white dwarf has at most 1.4 solar masses. So the white dwarf that was swallowed makes up less than 10% of the total mass of Betelgeuse, i. e. it can't have a big effect on its behaviour.

@@bjornfeuerbacher5514 you are right on a lot of things, but there is a paper that does suggest it. I am merely giving one reason for its odd behaviour. Aren't you mixing up nova and type 1a supernova? Type 1a is the one where a white dwarf collects matter from its binary companion. Anyway, the suggestion is that a white dwarf is still orbiting within Betelgeuse and drags matter along somehow creating a swirl that basically prevents Betelgeuse from blowing of his outer mantle. It's a bit far-fetched, but stranger things have been observed

Don't worry, there's mountains of content coming. Just no live streams

You can't break the laws of thermodynamics. Eventually you have to let the heat out.

We'll let the IAU sort that out. First, it needs to be found.

I wouldn't give it more than 150,000 years at the longest, and unlikely more than 100,000. No kidding. Any day between now and then! The problem is, nobody knows what happens at a red supergiant core. It may be burning helium, or already neon. It's impossible to tell looking at the surface. On the last day of its life, it will be fusing silicon, and still look bloated and red, as it always had. It may be belching carbon, as it recently did, but the core is pretty much an isolated region, a fusion reactor which lives its own life, and exchanges matter with the rest of the star only in a thin surface layer. All we see is due to heat exchange between core and higher layers of hot gas, and red giants are balls of puffy, boiling, roiling plasma (a gas with electrons torn off nuclei). Streams of free charges are electric currents, so this plasma is interspersed with magnetic fields, which in turn direct the plasma streams. Modelling a start is a horrifically complex task: in addition to already complex hydrodynamics (a study how hot fluids, e.g., gas, move), accounting for electromagnetic forces on the fluids turns the problem into a magnetohydrodynamic one. It's not solvable mathematically, only amenable to supercomputer numeric modelling. Simply speaking, you chop the star into cubes, as if space were discrete, and chop time into discrete timesteps. Then you compute how these cubic volumes tug on each other to compute pressure, flow, currents, magnetic fields etc., to get the numbers for each cube on the next timestep. Then rinse and repeat. Stuffing a whole Betelgeuse-sized star into even a huge supercomputer is not a simple task: if you chop it into cubes 1000km in size and time into 1 day steps, your computation will be very imprecise, rubbish, really. If you go with cubes of 1cm in size (how many do you'll get if you slice a supergiant into cheeseboard-sized cubes?) and slice time into 1 second steps, you'll get an excellent model, but it will take longer than your lifetime to run it to evolve the star. And worse, we don't know what to put into the model, we run a model for a month, compare the result with observation, get nonsense, tweak parameters, run it for another month, get less nonsense if we're lucky-it's an informed trial and error guessing and years of work of many people and supercomputers till the model starts to reproduce real star evolution. And, of course, we can't peek even into the Sun below its photosphere, visible "surface"-this is what the Parker Solar Probe is for, namely to measure other, non-light stuff, like magnetic fields and particle fluxes. But we cannot launch a probe to Betelgeuse... All we see is a few pixels, and that's the _only_ star except the Sun we have more than one pixel of. As Fraser said, spectra give much more info, but even that by far not all there is-it's only what we can glean from the Earth. This is why we suck at predicting the final evolution of a supergiant. Luckily, there are also Antares and η Carinae which are also going to go supernova within this time frame. η Car may go off much sooner. The main star in this multiple system is a huge, ~100MSol wildly pulsating LBV which had two recent supereruptions in the 19c. We don't know if supereruptions predict an imminent supernova, LBVs are rare stars, but there was an LBV supernova that blew up only 6 years after a similar supereruption event. The Carinae nebula, a huge stellar nursery (one of the first JWST images, if you recall), has quite a few supernova candidates. Betelgeuse, Antares and Eta are not the only stars which may give us a nearby supernova to study. As you already understand, their "when" may also happen today. There's about a dozen stars like that, Betelgeuse just stole the thunder thanks to the media feedback.

@@cykkm Uhh, thank you for a detailed response but you totally missed the point within the context of the question that was asked in the video. The question was - if Betelgeuse goes supernova at the time when our Sun is between our planet and Betelgeuse, how bad is it for our observation? Fraser said it's pretty bad because most of our instruments are boud to Earth (including JWST) and will have oversaturation from our Sun (or be outside of observation cone for JWST) to properly observe all the astro-science goodness that's happening in the first hours of the supernova event. He added it's not the end of the world (unless you're orbiting Betelgeuse) because we have a couple of backup options on or around Mars that could take a few pics, however, we would miss out on a lot of good science due to the position of the Sun. So, my (rephrased) question now is, what percentage of the year (time in general) is the Sun's position interfering with our best effort to observe the event? Extra question: how much of an advance notice do we get from neutrino detection and can we pre-program some contingency subroutines into our assets around other planets to point their eyes to Betelgeuse during those periods of occlusion (either automatically every year, or on command once we get a neutrino burst indication that something's going on)?

Think of it this way. If you want to observe a star 10 lightyears away and send the spacecraft 5 lightyears in that direction. Sure, that might help a little. But even with future technology that would take decades. And our galaxy is 100.000 lightyears across, not to mention all the other galaxies millions of lightyears away. Unless faster than light travel is possible (which it almost certainly is not) we might as well build our telescopes closer to home. And don't be afraid to ask silly questions. The best way to learn is to keep asking questions.

It's always a balance between how difficult it is to send a telescope far away and communicate with it. Especially when you're talking about light-years. We couldn't send a 1 kg telescope light-years away. For now, we're stuck at home using bigger and bigger telescopes to make the distant places look closer.

@@frasercain I'm honoured with your reply, Fraser. *Genuflects deeply*

I knew, but I'm still impressed all the time by the depth of Fraser's knowledge. In his interviews with scientists there seems to always be this "phew!" moment where the scientists realize they use professional explanations of their work instead of the dumbed down version.

Sure. The focus is a bout 550 AU or so away, Fraser has interviewed Slava Turyshev who is working on sending a telescope there to take advantage of the solar gravitational lens effect.

Only the largest stars will go supernova. You'll want to avoid them.

We're overdue, actually.

I was just thinking of that. I'll see what I can do.

@@frasercain Great! The video from when they came out didn't give any details, it was just "thank you to our families" etc.

Okay, I emailed their press office

@@frasercain Hopefully that gets the ball rolling. Ariane 6 went well, except for having the 2nd stage staying in orbit for possibly a decade or two.

There's a limit to supernova size to avoid collapse into a black hole. I doubt other galaxies will have more massive novas, but they might have more of them. Supernova create huge amounts of very unstable elements. It's possible that these are available long enough after the explosion to be incorporated into a planet, but decay quickly enough to be essentially gone from Earth. Look at the Wikipedia article "List of radioactive nuclides by half-life" for elements below about 10^16 seconds.

@@ericsmith6394 Thx M8

It takes a few million years for the entire process. But they've been seen at each stage of formation.

I've talked about it many times on the channel. Neutrinos aren't hampered by matter so they escape immediately while photons get held up by the infalling matter.

I'm reading one of his books right now. It's pretty tough and slow to get through, but it definitely fits the genre I'm into.

Sure, like for an interview?

@@frasercain not really an interview per se, as its government related she cant speak specifics but would be a great way for her to find out new information for briefings etc. Was just a thought

You just did it

@@frasercain hehe thanks. There is a 2 month break so i can ask later but if you can note my question for later, my real questions is: I have lately checked that most of the rocket first stages (not SpaceX) splash in water and sink beneath the ocean. Is it not a long term problem to accumulate space junk beneath the ocean bed? Thanks Fraser. Love your shows ❤️

The oceans are huge, and there are thousands of boats that have been sunk across the planet. In fact, many boats serve as places where reefs can form. We definitely want to move towards rocket launches that don't get discarded into the ocean.

A quick Google search reveals that the day is now 47ms longer than it was 3200 years ago. at tthat rate of slowing it will take about 15 million years for the rotaion period to increase to 24 hours.

@@rogerphelps9939 Thanks, I couldn't find that answer anywhere.

Don't worry, mountains of content still coming...

@@frasercain you were not wrong sir.