Andrew Dunkley: 15 seconds.

Guidance is internal.

10, 9.

Ignition sequence start.

Professor Fred Watson: Space nuts I.

Andrew Dunkley: 4, 3, 2, 1.

Space nuts.

Astronauts reported meals Good.

Hello once again and thank you for joining us on this edition of the Space Nuts podcast.

And my name's Andrew Dudley, your host.

And with Me for episode 193 is Astronomer in Charge from Professor Fred Watson.

Hello, Fred.

Professor Fred Watson: Hello, Andrew.

I did used to be the Astronomer in charge.

That was my.

Andrew Dunkley: I thought I said Astronomer at Large.

Professor Fred Watson: Well, it's quite all right.

Andrew Dunkley: No, it's Freudian slip.

Professor Fred Watson: It's very.

And of course, um, uh, that's why I became the Astronomer at Large.

Because you only had to change four letters on the office door to make it unknown to you.

Yes, yes.

Andrew Dunkley: Um, the organ.

And that sort of harps on something we talked about a while ago where your organization has changed names about two or three times, but didn't change the lettering.

So didn't change the logo.

Professor Fred Watson: Exactly.

Same logo since 1991.

Andrew Dunkley: I think that's amazing.

Uh, very good.

Now, um, Fred, have you got enough toilet paper at your place?

Is my big question.

Professor Fred Watson: Well, it's very kind of you to ask.

Um, we haven't yet started tearing pages out the Astrophysical Journal to use in the bathroom.

Andrew Dunkley: Did you hear about the Northern Territory News?

Uh, the newspaper in Darwin?

They published an edition last week with several blank pages for people.

This whole thing is just insanity at the highest level.

There's so many people panicking over nothing.

It's.

Professor Fred Watson: You might want to explain the toilet paper issue, though.

Andrew Dunkley: I think most people are aware, but if you're not aware, I don't know where you've been.

But, uh, there's been a panic buy up of toilet paper in Australia and all the supermarket shelves are empty.

Every supermarket where I live has got no toilet paper because people have been panic buying because the prime minister said stock up because you might have to be isolated for a couple of weeks because of the coronavirus.

And everyone's freaking out about it.

Well, not everyone.

I mean, we don't care.

But a lot of people are freaking out about it.

But, uh, I'm going to bring some astronomy into this, Fred.

Professor Fred Watson: Oh, good.

I wondered where it was going.

Andrew Dunkley: I think this is the 2020 version of a caveman seeing an eclipse and thinking the world's going to end.

Oh, probably that's what this is.

Professor Fred Watson: Yeah.

Andrew Dunkley: So I think people need to take a long, hard look at themselves and give themselves an uppercut, to use an Australian term, and just get on with it.

This is ridiculous.

Totally ridiculous.

Professor Fred Watson: The good news is that um, those particular people will, you know, they'll never need to go and buy another toilet roll again.

Andrew Dunkley: Not for eternity.

They'll get like, they'll get buried with the stuff.

Professor Fred Watson: Yeah, that's right.

Andrew Dunkley: I'm suggesting that if they're going to, you know, panic, buy toilet paper, get some baked beans and some long life milk so that when you eat it it'll taste a bit better.

M Now let's get down to business.

Today on Space Nuts we're going to uh, look at something that scientists have discovered for the first time and that is that space time is dragging.

Not everywhere, but they've found that it is dragging in one particular place, which sounds unusual.

And what does dragging actually mean?

Uh, we're also going to look at a couple of clever, uh, students, um, uh, in terms of a name for the next Martian rover.

This follows on from Sojourner, which I think is a great name.

Spirit, Opportunity, Curiosity.

So what are they calling the next one?

We will tell you.

And a 17 year old intern at NASA Day 3 on the job has found a planet six times, uh, or nearly seven times larger than Earth.

I mean, how lucky is that?

Uh, those are some of the things we'll look at today on Space Nuts with Fred Watson.

Let's uh, start off Fred, with um, the fact that space time is dragging.

What is it dragging and why?

Professor Fred Watson: Uh, it's a phenomenon to do with the theory of general relativity, or rather the general theory of relativity, which of course was produced by Albert Einstein in 1915.

Uh, not long after that, I think about three years later.

Well, uh, let me just step back a minute.

That theory of course says that as soon as you put matter into space time and space time's really just space, but with a fancy name as, uh, soon as you put matter into it, because of course time's part of it as well.

Uh, as soon as you put matter into space time it is distorted and that distortion is what we feel as gravity.

Uh, and that in itself is pretty hard to get your head around.

Space time bends because matters there.

But it was about, uh, I think three years later that two Austrian scientists, uh, by the name of Josef Lenzer unt Hans Turing, um, they worked out that uh, you would get a phenomenon, um, if you have a massive object rotating, you get a phenomenon which is almost a swirling of the space time around the object.

It's called frame dragging.

Um, and so as the Earth does it, as the Earth turns, it's not only distorting the space that's holding us on with the Force of gravity, but to a much less, a much lesser degree, it's also dragging the surrounding space time with it.

Now I know you're looking baffled, Andrew.

Andrew Dunkley: It's just a lack of sleep because I'm worried about where I'm going to get a roll of toilet paper.

Professor Fred Watson: Well, just watch out.

Don't drag your space time with it when you find it.

Um, we usually Anglicize, uh, uh, Josef and Hans names to the lens theory precession or lens theorying effect.

Andrew Dunkley: Okay.

Professor Fred Watson: Um, that's um, how most people speak of it, even though they wouldn't have called themselves that.

Uh, so, uh, okay, it has been tested, this theory.

It was um, as I said, I think it was 1918 when it was uh, when it was produced.

Um, but uh, the first test of it was done in the early 2000s.

A spacecraft called Gravity Probe B was launched into orbit around the Earth by NASA in collaboration, I think with Stanford University, um, which carried on board very, very sensitive gyroscopes.

And by using those, uh, the uh, physicists running the experiment could detect the frame dragging of the Earth itself.

So it's all about subtle motions in the satellite and that tells you that yes, you have proved, because there's nothing else that would give rise to those subtle motions, you've proved that frame dragging is true, uh, but it's only been detected around the Earth.

So now cut to the chase, uh, because uh, for the first time, uh, it has now been detected in an astronomical object.

Uh, and this is a really nice story because it pulls together uh, the fundamental physics of frame dragging with some of the big adventures that here in Australia we are taking part in, uh, particularly in terms of radio astronomy.

The story goes back 20 years actually, Andrew, uh, to the Parkes Radio Observatory, uh, in New South Wales, the very same state that we are both in at the moment.

Andrew Dunkley: One hour drive from that telescope.

Professor Fred Watson: Yeah, yeah, that's right.

You are indeed.

Exactly.

It's just down the road for you.

Ah, very, very well known telescope, uh, the Big Dish it's usually called.

Andrew Dunkley: And very distracting when you're driving along the highway because you just want to look at it.

Professor Fred Watson: You can't stop looking at it.

I know I don't have that problem because usually when I go down there, that's where I'm going.

So I just watch it getting bigger as you get nearer to it.

Um, 20 years ago, uh, the Parkes radio telescope discovered uh, a white dwarf pulsar binary system.

Um, I'll tell you its name and then we can get that out of the way.

It is, actually.

I've got to magnify the screen so I can read it.

Now, Fred, you're showing your PSR, uh, J1141 minus 6545.

There you are.

Uh, put that in your diary.

That's good already.

As have I.

Uh, it is a white dwarf pulsar, uh, binary system.

What does that mean?

It means you've got a white dwarf star, which is, um, an object the size of the Earth, but with the mass of a star in it.

Uh, made of electrons all crushed together.

Uh, or the electrons are the only thing that hold that.

Hold the thing that start the thing from collapsing.

So, um, that is a massive object.

Uh, around it is this pulsar, which is another massive object, uh, a neutron star.

Uh, the two are in mutual orbits and the, uh.

So the telescope discovered that phenomenon, the binary system.

So the pulsar itself is beaming out radiation from its poles.

Pulsars, as you know, because you and I have spoken about this before, uh, effectively are extremely accurate clocks.

They basically blip out radio radiation as they rotate.

That's what the Parkes dish detected.

And, um, the precision with which they do that is better than atomic clocks.

They are so regular.

Um, Just as one smaller piece of information in this.

The pulsar itself orbits the white dwarf every 4.8 hours.

So it's, you know, it's a.

It's whizzing round.

That's right.

Um, now what has happened over the last 20 years is that astronomers have been able to use this timing phenomenon, the regular timing of the pulsar, to measure the pulsar's position in respect to the white dwarf.

Uh, because essentially time.

Accurate time means accurate distance in terms of, uh, measuring where the pulsar is.

And it's that measured over 20 years that has demonstrated that this frame dragging phenomenon is taking place out there, uh, at PSR, whatever it was.

Uh, J1141 minus 6545.

Um, so what the scientists.

And there's a group of scientists from, uh, many different institutions, including, uh, institutions in Germany, the Square Kilometer Array Organization.

That is, uh, the headquarters of this great new telescope that we're planning, the Square Kilometer Array in Western Australia and in South Africa.

Uh, the headquarters are in Manchester, uh, or near Manchester at the Jodrell Bank Radio Observatory.

One of the scientists involved with this work, uh, comes from that organization.

Uh, so that means, uh, he is relatively closely connected with Australia because Australia is one of the host nations.

Uh, and I should just mention that the Parkes dish, uh, plus another telescope called the Malonglo Observatory Synthesis Telescope again here in Australia, uh, which has been involved with this work.

They are both Pathfinder telescopes for the Square Kilometer Array.

So very important in this large scale project that is currently uh, under construction or, uh, soon will be under construction, um, that's getting in the plug for ska.

But the research itself, as I said, involves scientists from Germany, Australia, New Zealand and actually Denmark too.

Um, and what they've done is they've um, looked at the way these pulsar signals have changed over the 20 years and they find a change in the pulsar's orbit which amounts to 150 kilometers.

Uh, and we're now talking about something that's 10,000 light years away.

Andrews Being able to measure uh, a change in orbit of 150 kilometers, uh, at that distance is an astonishing accomplishment.

But it turns out that that change is exactly what you would expect from frame dragging by the white dwarf itself.

And that's the only thing that can account for it.

So it is the first time that we've demonstrated this swirling of space actually, uh, uh, beyond the Earth's vicinity.

And it's an important, um, you know, a really important result which is rightly being celebrated all over the science media, um, astronomers, detective, Distant space time dragging for the first time.

Andrew Dunkley: So I guess the point of this is the massive um, or the mass of this event rather than, you know, we talked about how Earth does it, but we're talking about something on a much larger scale.

Professor Fred Watson: That's right, yes.

Uh, well, the white dwarf itself, whilst it's probably not much bigger than the Earth, uh, its mass is much larger.

Yeah, uh, and yeah, you're talking about, um, you know, you are talking about something happening on a larger scale.

I confess that um, I am not an expert on the lens searing effect, uh, but it is very interesting stuff.

Uh, and when you read up about it, it's quite inspiring that, you know, all those years ago these guys worked out that space time is being dragged around by the Earth.

Andrew Dunkley: And if you like me and you don't want to read anything about it, there's a fabulous animation on the skatelescope.org website where you can see um, in about 1 minute and 20 seconds what they've learned over 20 years.

It shows you how uh, effect works.

It's very, very good.

Professor Fred Watson: Um, I might give a call out to the, the person who put that uh, animation together, Mark Myers, who's at Swinburne University, uh, because I was in touch with him yesterday.

I'm using one of his, um, graphics in a newsletter that I prepare and I asked him if that was all right.

He said he, uh, was delighted to let us use it.

And I absolutely agree with you, Andrew.

His animation, uh, which is on that website, the skatelescope.org website, is terrific.

Andrew Dunkley: Yes, indeed.

All right, you're listening to the Space Nuts podcast.

Andrew Dunkley here with Fred Watson.

Let's take a break from the show and hear a word or two from our sponsored Grammarly.

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So if you'd like to download Grammarly today, go to getgrammarly.com spacenuts again, that's getgrammarly.com spacEnuts to download Grammarly for free and let them know you came from us.

Uh, I'll include the link in the show notes as well.

And now back to Space Nuts.

Three, two, one.

Space Nuts.

Now, Fred, uh, just, uh, another shout out to our patrons who support our podcast with dollars and cents.

We, um, thank you again for doing that.

If you would like to become a patron or just look into the possibility, uh, you can go to Our Patreon website, patreon.com spacenuts all the information's there.

If you would like to contribute to the program, you can set your own limit.

Um, but it's not mandatory.

We're not asking you to do it as, as a condition of listening to the podcast.

If you want to go on listening to it, uh, as you are, that is fine too.

But uh, anybody who contributes does get the benefit of bonus content on the Patreon website.

Uh, they also get the commercial free edition of the podcast, uh, ahead of time.

So, um, something to consider anyway, um, now, uh, by the way, Fred, um, my uh, new book, um, Shameless Plug coming up, uh, is now available for pre order as an ebook.

So, um, have a look for that on the Amazon website.

So, um, that's, that's pretty exciting.

I very, very pleased with how it's all turned out.

Uh, someone actually messaged me the other day and said I've ordered it, better be good.

Professor Fred Watson: Uh, you've got to remind us of the title, Andrew.

Andrew Dunkley: It's called, uh, the Turanian Enigma.

The Tyranny Enigma.

I'm starting.

First time I wrote that down and read it out, my tongue tripped over it and I thought, no, this is, this is too hard.

But I'm getting used to it now.

Professor Fred Watson: Very good.

Andrew Dunkley: I've developed a couple of synapses in my brain that have got my mouth around the Turanian in.

No, no, I tripped over it.

But um, yeah, have a look for it.

Uh, the official release date of the ebook and the paperback will be April 15th.

And um, a few people have asked if I could turn it into an audiobook as well.

So I'll look into that.

It's just so time consuming to create an audiobook.

Uh, not so much the reading and recording of, but the editing.

Oh my gosh, that's a nightmare.

Uh, having.

Professor Fred Watson: Well, you did that for, um, almost.

Andrew Dunkley: There's Mud, which was a World War I story about my grandfather in the Great War.

But that, that started as an audiobook.

So that was.

I sort of flipped the egg on that.

I did the audiobook and then, uh, made the paperback.

But these last two I've done the other way around or haven't done the other way around.

But um, I'll, I'll look into it.

I'll just.

It's got to be feasible.

And that, that sort of becomes the question.

But, um, we'll see how the demand goes.

But yeah, have a look for it.

Um, Huw tells me he's going to put it on our um, bytes.com spacenuts page.

So you might be able to pre order through there.

I haven't checked.

Uh, now let's get down to a couple of things involving students.

Fred.

These are, uh, um, exciting stories.

I particularly like this one, which involves the naming of the next Mars rover.

Now we've uh, heard of Sojourner and Spirit and Opportunity and Curiosity, uh some of which have gone above and beyond the call of duty.

Uh, but um, they aren't the last rovers.

They'll be future rovers.

And uh, it looks like some students have got involved in the naming of the next one.

Professor Fred Watson: Well, that's right.

It was uh, uh, uh, you know, I think this is what NASA does normally with its rovers.

Uh, it puts out a um, competition, uh, to uh, actually to school students, uh, and says suggests names for our next rover.

And of course the next rover is what's been called until now Mars 2020.

Um, it will be launched uh, July or August this year.

I think its landing date on Mars is the 18th of February next year.

So, um, uh, just under a year away until now, called Mars 2020.

So during the closing months of last year, NASA put out the invitation to school students, I think it was, uh, school students of all ages from kindy to year 12.

Uh, and uh, invited them to submit suggestions uh, for the um, name, uh, of the rover.

And they received uh, 28,000 submissions.

Andrew Dunkley: I know, that's amazing.

Professor Fred Watson: It's not bad, is it?

That was uh, back in August, at the end of August last year when they put the invitation out.

Uh, but fortunately, uh, it wasn't just one person who had to read all 28,000 because these were essays, uh, saying why it should be a particular name.

They had 4,700 volunteer judges.

They were educators, uh, professionals in the space field and space enthusiasts.

And they eventually got down to 155 semi finalists and then nine finalists.

And I think, I can't remember, but I think you and I talked about this last year because there was a list of uh, very elegant.

They were all great names actually for uh, a rover.

Andrew Dunkley: Robert.

Professor Fred Watson: Uh, and then they put that out for public voting and in fact it was worldwide and there were many submissions came from Australia.

They received a total of 770,000 votes to, to, you know, to chew through, to work out what uh, the final name should be.

And eventually, uh, they got one answer and it came.

Andrew Dunkley: Hang on, Drumroll, drumroll.

Professor Fred Watson: Uh, it came from uh, a youngster by the name of Alex Mather, uh, who's at a school.

I've forgotten.

I think he's in Virginia.

I can check that in a minute.

Uh, but he.

And here's the drum roll.

He was the person who suggested the name Perseverance, which is nice of the new spacecraft.

Yeah, yeah.

Andrew Dunkley: That is a fabulous name for it because it does actually tell a story behind all the missions to Mars over the years and all the work that's gone into it.

They just, you know, uh, all the successes and the failures and the near misses.

It is Perseverance that's going.

Professor Fred Watson: That's right.

I mean this spacecraft as well could be uh, it could be the one that discovers life on Mars because that's what it's, you know, what the aim is.

Um, uh, unlike Curiosity, whose mission was to discover whether Mars was ever habitable, which it did within about the first fortnight of its presence on the planet, um, uh, Perseverance is looking for evidence of past or present life, um, with many different instruments that will, will do that.

Uh, and I suspect perseverance might be the characteristic that it needs more than anything else.

It will probably be quite a long mission.

Uh, it's unlikely that, you know, as soon as it drops down it's going to find evidence of um, Martian microbes.

One would expect that it might have to move around on the surface a bit, but it will do that.

Andrew Dunkley: Only slightly pipped, uh, the number two, which was Do I have to go to Mars?

Professor Fred Watson: Yeah, that's the one.

Andrew Dunkley: Yeah.

Um, I'm fascinated by the fact that uh, they got 28,000 submissions for the name.

It reminds me of an author, a children's author in Sri Lanka last week who got 20,000 submissions for the ending of her latest book.

And they came out and they're going to publish it with 1,250 endings, which is, which is a, um, Guinness World Record.

And I, I think those sorts of responses really show where you stand in the world.

So when I asked for a title for my book, I got five.

Professor Fred Watson: Yeah, you did.

I think that's pretty good.

More than, more than the number of people who read my book.

Um, um, the bottom line here is congratulations to young Alexander Mather.

He is uh, a year, sorry a grade seven student.

Now I, I'm, I'm guessing that that means he's about 13, uh, or thereabouts.

Um, and uh, he put in, put together a really uh, remarkable, um, you know, remarkable uh, um, entry.

Um, he said some very, very, very uh, nice comments about the, the competition.

And his, his uh, his, his um entry to it, he says, um, this is actually in the NASA press release.

He says this was a chance to help the agency that put humans on the moon and we'll soon do it again.

This Mars rover will help pave the way for human presence there.

And I wanted to Try and help in any way I could.

Refusal of the challenge was not an option.

Lovely.

That is great stuff, isn't it?

Andrew Dunkley: Good on him.

Okay, uh, so watch out for perseverance, uh, which should hit the Martian surface in little under a year.

Still, uh, on students doing great things.

Uh, this is a fabulous story about a 17 year old who's doing an internship at NASA and has found a planet on day three.

Professor Fred Watson: Day three.

That's right, it is.

It's great stuff.

Um, so, uh, this is a young man called, uh, Wolf, Cukier, I hope I'm pronouncing his name correctly.

Uh, he scored a two month internship with NASA.

Uh, so during last northern summer he was at the Goddard Space Flight center in Greenbelt in Maryland.

And, um, what he was doing, uh, on day three, I think he probably started off doing this.

He was trawling through data from tess.

Uh, so TESS is a NASA spacecraft.

It is currently operational, doing a great job.

The name is an acronym for Transiting Exoplanet Survey Satellite.

So it's actually looking for the dimming of the light of stars as planets pass in front of them.

And unlike Kepler, which only looked at a small, uh, area of the sky to do the same job, Kepler, now effectively defunct tess, uh, actually looks at the whole sky.

Uh, so the word survey in its name is very important because it actually has a chance to look at the entire sky.

So he was looking through the data.

Actually there's a nice quote again, um, from Wolf.

He says, I was looking through the data for everything the volunteers had flagged as an eclipsing binary.

That means, uh, two stars orbiting around their common center of mass.

One passes in front of the other as seen from the Earth.

And so you get what we call an eclipse.

So they're well known stars.

They've been well known for more than a century.

It was looking, uh, through everything Volunteers had flagged as an eclipsing binary.

A system where two stars circle around each other and from our view, eclipse each other every orbit.

About three days into my internship, I saw a signal from a system called TOI 1338.

At first I thought it was a stellar eclipse, but the timing was wrong.

It turned out to be a planet.

Uh, I noticed a dip or a transit from the TOI 1338 system.

And that was the first signal of the planet.

First saw the initial dip and thought, oh, that looked cool.

But then when I looked at the full data from the telescope at that start, I and my mentor also noticed three different dips in the system.

So great stuff and very well spotted.

Andrew Dunkley: And it's a big one too.

Professor Fred Watson: Yeah, that's right.

Andrew Dunkley: Planets, I suppose.

Professor Fred Watson: Um, it's somewhere between the size of Neptune and Saturn.

Uh, rather larger than Uranus, about seven times larger than the Earth.

It's in the constellation of Pictor and it's about 1300 light years away.

Andrew Dunkley: Um, is it a gas giant or a rocky planet?

Professor Fred Watson: Probably.

Probably a gas giant.

Yeah.

The name, uh, uh, uh, TOI 1338.

TOI is an acronym for TESS, Object of Interest.

Uh, and, uh, um, it's one that's floating around a lot these days with a number attached to it.

So of course, um, because of the convention, uh, that planet that, uh, Wolf has discovered is now called TOI1338B because the B signifies it is the first discovered planet around the star.

Andrew Dunkley: Excellent.

All right.

Professor Fred Watson: Great stuff.

Andrew Dunkley: Yeah, good, good stuff with involving students, um, doing wonderful things.

You're listening to Space Nuts with Andrew Dunkley and Professor Fred Watson.

Space Nuts and a big hello to all our social media followers that contribute, um, via our Facebook page.

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Now, Fred, uh, we have a couple of questions.

I didn't, uh, preview these because I forgot, but, uh, we, we are going to tackle a couple of questions and then we're going to do, um, a little bit of homework or go back to something we talked about a couple of weeks ago just to finish it off, which was the Roche limit, which, which actually came about as a result of a question.

But our first question today comes from Andrew Mitchell.

I think Andrew's been in touch with us before.

Dear Fred and Andrew, all this recent talk about black holes has been fascinating.

And the last installment got me thinking.

According to Einstein's equations, black holes are supposed to have, uh, infinite, uh, supposed to be infinitely small, infinitely dense singularities at their center.

If that's the case, then how do uh, two actually merge into one black.

Shouldn't they just keep orbiting each other, getting closer forever?

Or is the fact that black holes do merge actually evidence that singularities have size?

Perhaps a sphere with a diameter of one Planck length?

Uh, your regular plugs and YouTube Music channel have been paying off.

I just became subscriber number 993, so it would, you know, we're a bit overdue getting your question done, Andrew.

Thanks for joining us on YouTube Music though still loving the show.

Um, please keep up the mind blowing stories.

Thank you, Andrew.

Um, black holes, gee, we don't talk about them very often.

Um, but yeah, it's an interesting question because we talk about how the, the black hole itself is quite small when you compare it to the event horizon or the, or the, you know, what's going on around it.

Um, but yeah, two merging black holes, do they actually merge?

And how is it.

So.

Professor Fred Watson: It'S a really good question.

Um, it's, you know, the whole black hole thing is hard to get your head around, whether you're a physicist or an astronomer or somebody fighting over toilet rolls in the ah, aisle.

Andrew Dunkley: Vesuva involves a black hole too, doesn't it?

Professor Fred Watson: I'm sure it does, yeah.

They are very, very hard, uh, objects to understand.

Uh, and Andrew's question made, um, how do two black holes merge into one?

Um, I don't think there is any need for them to keep orbiting around each other if they are of infinitely small size.

I do get his point that if you've got something that's infinitely small, uh, and you put something else that's infinitely small next to it, they're never going to, they're never going to touch, uh, because the dimensions are infinitely small.

But in fact, as Andrew says, they do merge.

We have evidence of that, uh, from the gravitational wave observations that have been made, um, over the past, uh, two or three years.

Um, and uh, there is this phenomenon, um, called the ring down, which is the sort of aftermath of the merging.

Now I don't know enough about black hole physics to understand specifically what the mechanism of the ring down is, but I suspect that is where the evidence comes that you actually have now merged black holes.

In fact, we know the evidence is there, um, because you wind up with a black hole whose mass is actually usually slightly less than the sum of the masses of the two black holes that have merged.

And um, the excess has gone into creating the gravitational waves.

It's mass into energy.

Uh, but um, Andrew goes on to make an interesting point.

He says, or is the fact that black holes do merge.

Actually evidence that singularities have a size, perhaps a sphere with a diameter of one Planck length.

Now introducing the Planck length is a really, ah, neat way of sidestepping the idea of an infinitesimally small object, because the Planck length is defined as being the smallest distance.

And it does have a proper physical definition.

In fact, it's actually the distance that light travels in one unit of Planck time.

Uh, so that raises the question, well, what's Planck time?

Um, let me just summarize though, and this is coming directly off Wikipedia.

The Planck length can be defined.

Uh, sorry, uh, from.

Yeah, let me read it.

The Planck length can be defined from three fundamental physical constants.

The speed of light in a vacuum, the Planck constant.

That's something, um, which physicists are very familiar with.

And the gravitational constant.

It's the smallest distance about which current experimentally corroborated models of physics can make meaningful statements.

So what it says is.

And I'll go on.

At such small distances, the conventional laws of macrophysics no longer apply, and even relativistic physics requires special treatment.

The bottom line is that a Planck length below that, all bets are off.

We really don't understand what is happening to the physics.

And maybe Andrew's point is well made that, uh, a Planck length black hole is actually what you have at the center of, uh, constituting a black hole system.

Um, I need to talk to my, uh, expert friends about this because, um, at this level of technicality, my knowledge is not specialist, But I do know people whose knowledge is far better than mine.

And next time I run into them, uh, I'm going to ask them exactly about these questions and hopefully feed back to space nuts and to Andrew and his, um, fellow listeners.

Andrew Dunkley: Okay, so the question remains open, Andrew.

Professor Fred Watson: Yeah.

Andrew Dunkley: I think we'll give you a definite maybe.

Professor Fred Watson: Maybe it's the answer.

Yes.

Andrew Dunkley: All right, thanks, Andrew.

Thanks for the question.

Let's move on to a question from Ulf Petersen in Sweden.

Yeah, uh, alf, I've got some news from you which you may or may not be aware of, but, uh, a young lady named Julia Engstrom, A professional golfer from Sweden, Just won the new south wales women's open, which we hosted here in dubbo a couple of weeks ago.

Professor Fred Watson: Great.

Andrew Dunkley: I.

Because our course was closed to play for members, um, uh, we got to go out there and watch these young ladies go around.

It was a European tour event.

Uh, she won not only her share of the prize money, but a two year exemption on the European tour.

She's 18 years old.

And she swings it like a champion.

I mean, she was hitting it 260 to 280 meters, whaling it past me.

And she's just a slip of a kid, but, uh, remarkable player and someone to watch out for in the future, if you're a golfer.

Julia Engstrom is her name.

So there you go, Ulf.

A little bit of.

I can feel his pride swelling now.

Um, now he says hello, uh, Andrew and Fred, uh, what a fantastic community you've started.

And it's a global one, too.

I've been a faithful listener of your pods now for a year and enjoy them very much.

Never imagined Thursdays could be that exciting.

I'd usually say something derogatory, but I'm feeling good today.

Um, don't know if this question might be of interest to the show.

Is there any chance that it's a black hole question?

By the way, Fred, is there any chance that a black hole might not exist in its, uh.

Inside its event horizon?

After all, black holes are claimed to be singularities that is infinitesimal in size.

In practical terms, nothing.

Right.

Uh, if so, could an event horizon act as a sort of a delayed postal service, never informing anyone outside what has happened?

So, like Australia Post, really?

Um, no, they're great.

Actually, uh, there's another piece of news.

Dubbo Post Office here in town.

Got Post Office of the Year.

Professor Fred Watson: Oh, uh, fabulous.

That's great, Nick.

Andrew Dunkley: About a month ago.

So we're doing it right here, aren't we?

Professor Fred Watson: Uh, you're doing well in Dubbo.

Andrew Dunkley: Extra questions.

Would physics allow matter still to be pulled into the vent event, uh, into the horizon, even if the black hole was gone?

Professor Fred Watson: Great, uh, question, Ulf.

And, um, In.

In a sense, the.

The, um.

He's right about the event horizon acting as a delayed postal service because, um, it stops the transfer of information.

We do know that, uh, black holes can evaporate courtesy of Hawking radiation.

But, um, basically.

And that involves the transfer of information.

We know that, but it's very, very slow.

So the event horizon does shield the black hole from the outside world, if I can put it that way.

But, um, in terms of whether the black hole itself exists, it's kind of the other way around.

The only way the event horizon can exist is if there is a black hole at the center.

Uh, in other words, this infinitesimally small singularity, essentially distorting space time to the extent that you've got this shield around it, this black hole.

The black hole.

Uh, sorry, the black hole.

Event horizon.

The event horizon, in some ways, Is an illusion, Andrew, because, um, it's just the point of no return.

It's the thing that won't let light out.

And it certainly is black.

We've seen that from the event horizon image, uh, that was released last year.

But, uh, without the black hole, the event horizon doesn't exist.

So, uh, there has to be this singularity at the middle with all its complicated, uh, infinitesimally small planck length dimensions that we've just been discussing.

Um, yeah, great question though, and thank you very much.

And yes, Sweden rocks.

I was there not very long ago.

Andrew Dunkley: And as monty python says, nothing can come from nothing.

Can't be nothing.

Professor Fred Watson: Yes, yes.

Andrew Dunkley: Um, thanks, alf.

Appreciate the question.

One more thing before we finish up, fred, and this is, um, a little bit of, um, an add on from a question about the roche limit.

A couple of weeks ago, we were trying to figure out the roche limit between the earth and the moon.

And as you explained, the roche limit is the point where gravity, uh, will destroy one of the objects involved, um, uh, in the, uh, situation.

So, um, you could probably explain it better than I just did.

But, um, uh, basically we were trying to figure out how close the moon could get to the earth before it was obliterated.

Yeah, life on earth would probably be obliterated too.

Professor Fred Watson: Well, that's right.

It would be a tricky situation for all of us.

But it is.

It's much less than I thought it would be, Andrew.

Um, the roche limit for the moon is 9,492 kilometers.

And I think that's from the center of the earth.

So it's actually 3,004, uh, 114 kilometers above the surface.

Imagine the moon 3,000 kilometers above the surface.

Whoa.

Andrew Dunkley: Wouldn't it look amazing?

Professor Fred Watson: It would look pretty amazing.

That's right.

Andrew Dunkley: Just for a few moments until we all died of fire or die.

Professor Fred Watson: I guess that's right.

Yeah.

Andrew Dunkley: But that's okay.

We'd have plenty of toilet paper.

Professor Fred Watson: Ah, ah, we would.

We'd be all right.

Yes.

Andrew Dunkley: So three, uh, so 9,000.

Professor Fred Watson: Yeah, 9,492 kilometers from the center of the earth.

Andrew Dunkley: Close as it could get before it was destroyed by our gravity.

And we would go down with the ship.

Professor Fred Watson: Absolutely.

Yeah.

Andrew Dunkley: In a nutshell.

All right, now we've got that sorted out.

Uh, thank you, Fred, so much.

It's always a pleasure.

Professor Fred Watson: It's always a pleasure talking to you too, Andrew.

And we'll speak again soon, I hope.

Andrew Dunkley: You will indeed.

And thank you for, uh, listening.

Thank you for your contributions.

Keep them coming.

We love to hear from you, whether it's on social media or via our website where you can send us emails.

Uh, we have a little contact form there, so you can send us questions and, uh, to the patrons.

There'll be some bonus material coming up real soon.

Uh, other than that, thank you and we'll see you again next time on another edition of the Space Nuts Podcast, Space Notes.

You'll be this to the SpaceNuts Podcast, available in Apple Podcasts, Google Podcasts, Spotify, iHeartRadio, or your favorite podcast player.

You can also stream on demand@ah, bytes.com.

Professor Fred Watson: This has been another quality podcast production from Thights.com.