Transcript
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Today I'm walking the trail from Lake Tekapo up to Ōtehīwai, Mount John. It's a few hours inland from
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Christchurch, New Zealand, and a place I used to come a lot as an undergrad studying astronomy at
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the University of Canterbury. At the top of this hill are some of New Zealand's biggest telescopes,
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and so I wanted to take this chance to talk about one of New Zealand's greatest astronomers.
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She changed the study of galaxies forever, and she was the first to grasp that galaxies, just
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like the stars within them, evolve with time. We are lucky to be able to look at pictures of space,
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like recent ones from the JWST, and know a little bit about what we're looking at. Each
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dot is a galaxy. That's an unfathomable truth, given how large our own galaxy is.
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And much of the science that goes on today, trying to understand these dots, was spearheaded by an
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astronomer from a small New Zealand town. Her name was Beatrice Hill Tinsley. She
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was a trailblazer. And as I walk up this hill today, I'm going to share with you her story.
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Much of what I know about Beatrice I've learned in this book, Bright Star by
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Christine Cole Catley. It was a hard book to find. I got this copy from an old and
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rare bookstore in Otago and it happens to be an old library copy. And it's a shame
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this book isn't more popular because I think that more people should know about Beatrice.
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She was born Beatrice Hill in England in 1941, but came to New Zealand as a baby
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and grew up in New Plymouth. As a young girl, there were a few books about astronomy that
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really fascinated Beatrice. One in particular was Fred Hoyle's The Nature of the Universe,
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which asked questions such as, how was the universe created?
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At age 14, Beatrice was hungry to know more and asked to borrow some physics textbooks
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from her school teacher's bookshelf. She worked through them by herself. A couple of years later,
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that same teacher was injured in a car accident just weeks before the
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school's final exams. Beatrice led her class to study without their teacher,
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and in the final exam, the students got excellent marks.
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This teacher later said that very occasionally, you realize you're dealing with a mind that is
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infinitely superior to your own. Beatrice came into that category. I would call her a
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genius. Beatrice graduated at just age 16 from New Plymouth Girls High School with top marks in her
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year, and she went on to study at the University of Canterbury, the same university I went to.
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She didn't like rote learning and preferred to teach herself interesting ideas. In a letter
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home from university, she wrote that she was sick of working for
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exams and decided to sit in the back of lectures and work on learning new maths
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rather than listening to the lecturer mumble through calculus she had learned at school.
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During her time at Canterbury, Beatrice decided that she wanted to be a cosmologist,
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but that wasn't really a topic offered at the university at that time. This
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observatory that I'm walking to now wasn't built when Beatrice was a student,
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so she had to do a different research topic for her master's thesis.
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Its title was Theory of the Crystal Field in Neodymium Magnesium Nitrate.
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Even though it wasn't the topic that she was passionate about it gave the added benefit
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of giving her skills using a computer, and she was one of the only people in
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the country who got those kind of skills, and that helped her later in her career.
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She got all A's at university and was the only woman in physics at master's level.
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She also won every academic prize available to her, including the Haydon Prize for Physics,
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which I also won 55 years after her. I do feel connected to Beatrice in lots of little
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ways. And she also won a postgraduate scholarship to continue her studies.
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However, her path after university wasn't so streamlined, and she faced many difficulties
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in continuing her studies. She got married at age 20 to fellow physics student Brian Tinsley.
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They moved together to Dallas, Texas. At the time, there were anti nepotism
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laws that prevented both a husband and wife from being employed at the same institution.
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And Beatrice hadn't known this when she got married and felt betrayed. It prevented her
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from continuing her research because Brian was already employed in Dallas. Feeling
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like her potential was languishing, Beatrice took matters into her own hands and decided
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to find somewhere that would let her do a PhD, even if it meant a long commute.
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At the University of Austin, a five hour bus ride away, she managed to convince a professor to give
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her a chance. They told her that most students struggled to complete the program in six years,
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working full time, but she needed to do it part time, splitting her
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time between Dallas and Austin. There is a comment in Catley's book about this time,
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saying that Beatrice used her scholarship to pay for all the travel plus Brian having to
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eat out half the week. This comment disturbed me a little, I guess it's evident that Brian
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wouldn't be expected to cook for himself, and it doesn't sound like Beatrice also
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got the luxury of eating out. It's only a small comment, but it does start to speak
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to the realities of her married life, which she later described as being like a prison for her.
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Regardless, she did very well at her PhD, and she astounded the professors and fellow students by
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scoring the first ever 100 on an exam there. In a letter home to her New Zealand family,
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she described the topic of her thesis by saying, I will be studying a whole
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lot of different theories of cosmology to see which is best able to explain
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the observations made with optical and radio telescopes on different galaxies.
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The theories are based on Einstein's General Relativity. Around the time of starting to write
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up her thesis, Beatrice was thrown a curveball. An unmarried member of her husband's family
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became pregnant and at that time, the baby would need to be adopted out. Beatrice was
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unexpectedly thrust into motherhood, feeling compelled to adopt the baby boy, named Allen.
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She wrote up her thesis while taking care of the baby, and remember how I said most students take
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six years to finish? Well, Beatrice made such impressive progress that she was able to finish
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it in under three years. An examiner at her oral presentation said it was such powerful
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work that they should simply award her the PhD then and there, without asking any questions.
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Although they did continue to ask some, just to meet the formalities. So what was her PhD
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work? Well, we can take a look at her thesis. Its title was Evolution of Galaxies and its
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Significance for Cosmology. In it, she makes some of the first quantitative predictions of
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how galaxies will change over time by looking at how the stars are evolving with time.
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She showed that galaxy evolution is something that can be observed
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and this was to grow into one of the largest subfields within the study of
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galaxies. She looked at the process of star formation and at how those stars
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would evolve and affect the recycling of dust and gas in the interstellar medium.
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This would shape the fate of the galaxy itself and Beatrice was able to model this
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interconnectedness. Previous to Beatrice's work,
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it was thought that galaxies could be used as standard candles to measure distances in space
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because they didn't change, but Beatrice showed that galaxies could dim with age.
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This had profound effects on how astronomers came up with theories
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of the fate of the universe. Without this insight, the leading theory had been that
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the universe would collapse in a big crunch. Taking into account the changing nature of
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galaxies meant the data now looked more in favor of the universe expanding forever.
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Further observations 30 years later using supernovae instead of galaxies
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as those standard candles were to show that the expansion of the universe was
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in fact speeding up under the influence of what astronomers call dark energy.
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Despite producing a great PhD in record time, Beatrice felt deflated after this achievement.
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She returned to Dallas with no job prospects. She did apply for some
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grants to try and continue her research from home and had short visiting stints at
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places like Caltech. She also adopted a second child, Teresa. From all that I've read so far,
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it is clear that Beatrice loved her children and did all she could to put them first.
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It's also clear that these years post PhD were a real struggle for her personally. When she'd
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moved to Dallas for her husband's job, it had been with an understanding that it would only
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be temporary. But nearly ten years later, she was still waiting for her turn to start her career.
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Everyone that met Beatrice could see her potential and see how bright she was.
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After a long time struggling, she knew that getting a divorce from Brian would
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be the only way that she could shine. She was offered an academic position at Yale
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and wanted to take the children with her, but Brian didn't want her to. To avoid the
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children being fought over in court, she gave way and moved to Yale on her own,
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continuing to visit and help with child care arrangements when she could.
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These aren't the kind of details I usually mention too much in my videos,
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and a case of people splitting up and having children live with one parent is an extremely
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common occurrence. In this case though, Beatrice seems to have received quite a lot of criticism
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on the matter. Her daughter Teresa was later quoted in a New York Times article saying that
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even though it was painful, she was proud that her mom stood her ground and followed her career.
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Moving to Yale, Beatrice finally got to work on the questions that she had
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been inspired to answer as a child, reading Hoyle's book about the origin
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of the universe. One of her papers was featured in Time magazine, which is why she posed for this
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photo shoot at the Blackboard. She published over 100 papers, and looking through them, you can see
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topics like chemical evolution, abundance ratios, metallicity distribution, and even dark matter.
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These are all topics that make up the modern field of galactic astronomy,
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and Beatrice was involved in all of them. Her most impactful paper was published in
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1980 called The Evolution of Stars and Gas in Galaxies. It received thousands of citations
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and its longevity is seen in the fact that papers published this year are still citing it.
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In it, Beatrice describes different aspects of galactic evolution such as
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gaseous inflow and the composition of the interstellar medium. She calls them pieces
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of a jigsaw puzzle that may someday be put together. Another notable achievement of
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Beatrice's was that she organized a big galaxy conference at Yale in 1977, which
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has been described as the single most important galaxy conference in the history of the subject.
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She also became Yale's first female professor of astronomy. But at the height of her career,
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this story took a tragic turn. Just a year after becoming a professor,
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she noticed a bleeding mole on the back of her leg that she had
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previously ignored. She was diagnosed with melanoma and underwent treatment.
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During this time, she still kept busy and looked after Teresa, who had come back to live with her.
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Beatrice continued to work throughout her illness,
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but over the course of a few years, became very sick as treatment failed to save her.
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Her PhD students visited her bedside and she helped them with their work.
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She continued to work on her own research too, and wrote her last paper from her bed
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in the Yale infirmary. She had to learn to use her left hand in order to write
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it out. It was called Chemical Evolution 4, Some Revised General Equations. It was
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submitted 10 days before she died, in March 1981, and it was published after her death.
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It includes calculations showing how to separate living stars from dead remnants,
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and thus making models more consistent.
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That building over there is where the astronomers work today. And inside there's a small library
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with a bound copy of Beatrice's PhD thesis. As an undergrad I got to stay there and
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meet Alan Gilmore and Pam Kilmartin, who, using one of the telescopes here,
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discovered an asteroid in August 1981 that they named Beatrice Tinsley.
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Beatrice's father, Edward Hill, called it a kind of moving tombstone. There are some other
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small traces of her legacy across New Zealand, like this street in Auckland named after her,
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and Mount Tinsley near Queenstown. But still, many New Zealanders don't
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know about Beatrice, and her impact on our understanding of the big questions.
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Beatrice was friends with Vera Rubin, whose work on galaxies provided key evidence for
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the existence of dark matter. I'd like to end with Vera's words about Beatrice. She said,
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Even in her all too brief a life, Beatrice was one of the giants of astronomy in the 20th century.
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There is no telling how much more we might have learned if she had had a longer time to teach us.
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While researching for this video, I saw that Christine Catley's daughter, Nicola Scott,
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is currently driving an attempt to make a movie about Beatrice, based on her mother's book. I
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hope this goes ahead, and that Beatrice's legacy can continue to shine on. Thank you for watching,
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and thank you to my Patreon supporters for making these videos possible.
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A special shout out to today's Patron cat of the day, Thorin.
