Archive for the ‘astronomy’ Category
In 2009, a poll held by the United Kingdom’s Engineering & Technology magazine found that 25% of those surveyed did not believe that men landed on the Moon. Another poll gives that 25% of 18- to 25-year-olds surveyed were unsure that the landings happened. There are subcultures worldwide which advocate the belief that the Moon landings were faked. By 1977 the Hare Krishna magazine Back to Godhead called the landings a hoax, claiming that, since the Sun is 93,000,000 miles away, and “according to Hindu mythology the Moon is 800,000 miles farther away than that”, the Moon would be nearly 94,000,000 miles away; to travel that span in 91 hours would require a speed of more than a million miles per hour, “a patently impossible feat even by the scientists’ calculations.”
From ‘Moon landing conspiracy theories’ , Wikipedia
Haha just for the record the Sun is nearly 400 times further from us than the Moon, but who’s counting? So now to the Apollo moon missions, and because I don’t want this exploration to extend to a fourth part, I’ll be necessarily but reluctantly brief. They began in 1961 and ended in 1975, and they included manned and unmanned space flights (none of them were womanned).
But… just one more general point. While we may treat it as inevitable that many people prefer to believe in hoaxes and gazillion-dollar deceptions, rather than accept facts that are as soundly evidence-based as their own odd existences, it seems to me a horrible offence in this case (as in many others), both to human ingenuity and to the enormous cost in terms, not only of labour spent but of lives lost. So we need to fight this offensive behaviour, and point people to the evidence, and not let them get away with their ignorance.
The Apollo program was conceived in 1960 during Eisenhower’s Presidency, well before Kennedy’s famous mission statement. It was given impetus by Soviet successes in space. It involved the largest commitment of financial and other resources in peacetime history. The first years of research, development and testing involved a number of launch vehicles, command modules and lunar modules, as well as four possible ‘mission modes’. The first of these modes was ‘direct ascent’, in which the spacecraft would be launched and operated as a single unit. Finally, after much analysis, debate and lobbying, the mode known as Lunar Orbit Rendezvous (LOR) was adopted. The early phases of the program were dogged by technical problems, developmental delays, personal clashes and political issues, including the Cuban missile crisis. Kennedy’s principal science advisor, Jerome Weisner, was solidly opposed to manned missions.
I can’t give a simple one-by-one account of the missions, as the early unmanned missions weren’t simply named Apollo 1, 2 etc. They were associated strongly with the Saturn launch vehicles, and the Apollo numbering system we now recognise was only established in April 1967. The Apollo 4 mission, for example, is also known as AS-501, and was the first unmanned test flight of the Saturn 5 launcher (later used for the Apollo 11 launch). Three Apollo/Saturn unmanned missions took place in 1966 using the Saturn 1B launch vehicle.
The manned missions had the most tragic of beginnings, as is well known. On January 27 1967 the three designated astronauts for the AS-204 spaceflight, which they themselves had renamed Apollo 1 to commemorate the first manned flight of the program, were asphyxiated when a fire broke out during a rehearsal test. No further attempt at a manned mission was made until October of 1968. In fact, the whole program was grounded after the accident for ‘review and redesign’ with an overall tightening of hazardous procedures. In early 1968, the Lunar Module was given its first unmanned flight (Apollo 5). The flight was delayed a number of times due to problems and inexperience in constructing such a module. The test run wasn’t entirely successful, but successful enough to clear the module for future manned flights. The following, final unmanned mission, Apollo 6, suffered numerous failures, but went largely unnoticed due to the assassination of Martin Luther King on the day of the launch. However, its problems helped NASA to apply fixes which improved the safety of all subsequent missions.
And so we get to the first successful manned mission, Apollo 7. Its aim was to test the Apollo CSM (Command & Service Module) in low Earth orbit, and it put American astronauts in space for the first time in almost two years. It was also the first of the three-man missions and the first to be broadcasted from within the spaceship. Things went very well in technical terms, a relief to the crew, who were only given this opportunity due to the deaths of the Apollo 1 astronauts. There were some minor tensions between the astronauts and ground staff, due to illness and some of the onboard conditions. They spent 11 days in orbit and space food, though on the improve, was far from ideal.
Apollo 8, launched only two months later in December, was a real breakthrough, a truly bold venture, as described in Earthrise, an excellent documentary of the mission made in 2005 (the astronauts were the first to witness Earthrise from the Moon). The aim, clearly, was to create a high-profile event designed to capture the world’s attention, and to eclipse the Soviets. As the documentary points out, the Soviets had stolen the limelight in the space race – ‘the first satellite, the first man in orbit, the first long duration flight, the first dual capsule flights, the first woman in space, the first space walk’. Not to mention the first landing of a human-built craft on the Moon itself.
The original aim of the mission was to test the complete spacecraft, including the lunar module, in Earth orbit, but when the lunar module was declared unready, a radical change of plan was devised, involving an orbit of the Moon without the lunar module. Apollo 8 orbited the Moon ten times at close quarters (110 kms above the surface) over a period of 20 hours. During the orbit they made a Christmas Eve telecast, the most watched program ever, up to that time. Do yourself a favour and watch the doco. The commentary of the astronaut’s wives are memorable, and put the moon hoaxers’ offensiveness in sharp relief.
By comparison to Apollo 8 the Apollo 9 mission (March ’69) was a modest affair, if that’s not too insulting. This time the complete spacecraft for a Moon landing was tested in low Earth orbit, and everything went off well, though space walking proved problematic, as it often had before for both American and Soviet astronauts, due to space sickness and other problems. With Apollo 10 (May ’69) the mission returned to the Moon in a full dress rehearsal of the Apollo 11 landing. The mission created some interesting records, including the fastest speed ever reached by a manned vehicle (39,900 kms/hour during the return flight from the Moon) and the greatest distance from home ever travelled by humans (due to the Moon’s elliptical orbit, and the fact that the USA was on the ‘far side of the Earth’ when the astronauts were on the far side of the Moon).
I’ll pass by the celebrated Apollo 11 mission, which I can hardly add anything to, and turn to the missions I know less – that’s to say almost nothing – about.
Apollo 12, launched in November 1969, was a highly successful mission, in spite of some hairy moments due to lightning strikes at launch. It was, inter alia, a successful exercise in precision targeting, as it landed a brief walk away from the Surveyor 3 probe, sent to the Moon two and a half years earlier. Parts of the probe were taken back to Earth.
The Apollo 13 mission has, for better or worse, come to be the second most famous of all the Apollo missions. It was the only aborted mission of those intended to land on the Moon. An oxygen tank exploded just over two days after launch in April 1970, and just before entry into the Moon’s gravitational sphere. This directly affected the Service Module, and it was decided to abort the landing. There were some well-documented hairy moments and heroics, but the crew managed to return safely. Mea culpa, I’ve not yet seen the movie!
Apollo 14, launched at the end of January 1971, also had its glitches but landed successfully. The astronauts collected quite a horde of moon rocks and did the longest moonwalk ever recorded. Alan Shepard, the mission commander, added his Moon visit to the accolade of being the first American in space ten years earlier. At 47, he’s the oldest man to have stepped on the Moon. The Apollo 15 mission was the first of the three ‘J missions’, involving a longer stay on the Moon. With each mission there were improvements in instrumentation and capability. The most well-known of these was the Lunar Roving Vehicle, first used on Apollo 15, but that mission also deployed a gamma-ray spectrometer, a mass spectrometer and a laser altimeter to study the Moon’s surface in detail from the command module. Apollo 16 was another successful mission, in which the geology of the Moon’s surface was the major focus. Almost 100kgs of rock were collected, and it was the first mission to visit the ‘lunar highlands’. The final mission, Apollo 17, was also the longest Moon stay, longest moonwalks in total, largest samples, and longest lunar orbit. And so the adventure ended, with high hopes for the future.
I’ve given an incredibly skimpy account, and I’ve mentioned very few names, but there’s a ton of material out there, particularly on the NASA site of course, and documentaries aplenty, many of them a powerful and stirring reminder of those heady days. Some 400,000 technicians, engineers, administrators and other service personnel worked on the Apollo missions, many of them working long hours, experiencing many frustrations, anxieties, and of course thrills. I have to say, as an internationalist by conviction, I’m happy to see that space exploration has become more of a collaborative affair in recent decades, and may that collaboration continue, defying the insularity and mindless nationalism we’ve been experiencing recently.
Finally, to the moon hoaxers and ‘skeptics’. What I noticed on researching this – I mean it really was obvious – was that in the comments to the various docos I watched on youtube, they had nothing to say about the science and seemed totally lacking in curiosity. It was all just parroted, and ‘arrogant’ denialism. The science buffs, on the other hand, were full of dizzy geekspeak on technical fixes, data analysis and potential for other missions, e.g. to Mars. In any case I’ve thoroughly enjoyed this little trip into the Apollo missions and the space race, in which I’ve learned a lot more than I’ve presented here.
- That such a huge number of people could seriously believe that the Moon landings were faked by a NASA conspiracy raises interesting questions – maybe more about how people think than anything about the Moon landings themselves. But still, the most obvious question is the matter of evidence.
Philip Plait, from ‘Appalled at Apollo’, Chapter 17 of Bad Astronomy
So as I wrote in part one of this article, I remember well the day of the first Moon landing. I had just turned 13, and our school, presumably along with most others, was given a half-day off to watch it. At the time I was even more amazed that I was watching the event as it happened on TV, so I’m going to start this post by exploring how this was achieved, though I’m not sure that this was part of the conspiracy theorists’ ‘issues’ about the missions. There’s a good explanation of the 1969 telecast here, but I’ll try to put it in my own words, to get my own head around it.
I also remember being confused at the time, as I watched Armstrong making his painfully slow descent down the small ladder from the lunar module, that he was being recorded doing so, sort of side-on (don’t trust my memory!), as if someone was already there on the Moon’s surface waiting for him. I knew of course that Aldrin was accompanying him, but if Aldrin had descended first, why all this drama about ‘one small step…’? – it seemed a bit anti-climactic. What I didn’t know was that the whole thing had been painstakingly planned, and that the camera recording Armstrong was lowered mechanically, operated by Armstrong himself. Wade Schmaltz gives the low-down on Quora:
The TV camera recording Neil’s first small step was mounted in the LEM [Lunar Excursion Module, aka Lunar Module]. Neil released it from its cocoon by pulling a cable to open a trap door prior to exiting the LEM that first time down the ladder.
As for the telecast, Australia played a large role. Here my information comes from Space Exploration Stack Exchange, a Q and A site for specialists as well as amateur space flight enthusiasts.
Australia was one of three continents involved in the transmissions, but it was the most essential. Australia had two tracking stations, one near Canberra and the other at the Parkes Radio Observatory west of Sydney. The others were in the Mojave Desert, California, and in Madrid, Spain. The tracking stations in Australia had a direct line on Apollo’s signal. My source quotes directly from NASA:
The 200-foot-diameter radio dish at the Parkes facility managed to withstand freak 70 mph gusts of wind and successfully captured the footage, which was converted and relayed to Houston.
And it really was pretty much ‘as it happened’, the delay being less than a minute. The Moon is only about a light-second away, but there were other small delays in relaying the signal to TV networks for us all to see.
So now to the missions and the hoax conspiracy. But really, I won’t be dealing with the hoax stuff directly, because frankly it’s boring. I want to write about the good stuff. Most of the following comes from the ever-more reliable Wikipedia – available to all!
The ‘space race’ between the Soviet Union and the USA can be dated quite precisely. It began in July 1956, when the USA announced plans to launch a satellite – a craft that would orbit the Earth. Two days later, the Soviet Union announced identical plans, and was able to carry them out a little over a year later. The world was stunned when Sputnik 1 was launched on October 4 1957. Only a month later, Laika the Muscovite street-dog was sent into orbit in Sputnik 2 – a certain-death mission. The USA got its first satellite, Explorer 1, into orbit at the end of January 1958, and later that year the National Aeronautics and Space Administraion (NASA) was established under Eisenhower to encourage peaceful civilian developments in space science and technology. However the Soviet Union retained the initiative, launching its Luna program in late 1958, with the specific purpose of studying the Moon. The whole program, which lasted until 1976, cost some $4.5 billion and its many failures were, unsurprisingly, shrouded in secrecy. The first three Luna rockets, intended to land, or crash, on the Moon’s surface, failed on launch, and the fourth, later known as Luna 1, was given the wrong trajectory and sailed past the Moon, becoming the first human-made satellite to take up an independent heliocentric orbit. That was in early January 1959 – so the space race, with its focus on the Moon, began much earlier than many people realise, and though so much of it was about macho one-upmanship, important technological developments resulted, and vital observations were made, including measurements of energetic particles in the outer Van Allen belt. Luna 1 was the first spaceship to achieve escape velocity, the principle barrier to landing a vessel on the Moon.
After another launch failure in June 1959, the Soviets successfully launched the rocket later known as Luna 2 in September that year. Its crash landing on the Moon was a great success, which the ‘communist’ leader Khrushchev was quick to ‘capitalise’ on during his only visit to the USA immediately after the mission. He handed Eisenhower replicas of the pennants left on the Moon by Luna 2. And there’s no doubt this was an important event, the first planned impact of a human-built craft on an extra-terrestrial object, almost 10 years before the Apollo 11 landing.
The Luna 2 success was immediately followed only a month later by the tiny probe Luna 3‘s flyby of the far side of the Moon, which provided the first-ever pictures of its more mountainous terrain. However, these two missions formed the apex of the Luna enterprise, which experienced a number of years of failure until the mid-sixties. International espionage perhaps? I note that James Bond began his activities around this time.
The Luna Program wasn’t the only only one being financed by the Soviets at the time, and the Americans were also developing programs. Six months after Laika’s flight, the Soviets successfully launched Sputnik 3, the fourth successful satellite after Sputnik 1 & 2 and Explorer 1. The important point to be made here is that the space race, with all its ingenious technical developments, began years before the famous Vostok 1 flight that carried a human being, Yuri Gagarin, into space for the first time, so the idea that the technology wasn’t sufficiently advanced for a moon landing many years later becomes increasingly doubtful.
Of course the successful Vostok flight in April 1961 was another public relations coup for the Soviets, and it doubtless prompted Kennedy’s speech to the US Congress a month later, in which he proposed that “this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth.”
So from here on in I’ll focus solely on the USA’s moon exploration program. It really began with the Ranger missions, which were conceived (well before Kennedy’s speech and Gagarin’s flight) in three phases or ‘blocks’, each with different objectives and with increasingly sophisticated system design. However, as with the Luna missions, these met with many failures and setbacks. Ranger 1 and Ranger 2 failed on launch in the second half of 1961, and Ranger 3, the first ‘block 2 rocket’, launched in late January 1962, missed the Moon due to various malfunctions, and became the second human craft to take up a heliocentric orbit. The plan had been to ‘rough-land’ on the Moon, emulating Luna 2 but with a more sophisticated system of retrorockets to cushion the landing somewhat. The Wikipedia article on this and other missions provides far more detail than I can provide here, but the intensive development of new flight design features, as well as the use of solar cell technology, advanced telemetry and communications systems and the like really makes clear to me that both competitors in the space race were well on their way to having the right stuff for a manned moon landing.
I haven’t even started on the Apollo missions, and I try to give myself a 1500-word or so limit on posts, so I’ll have to write a part 3! Comment excitant!
The Ranger 4 spacecraft was more or less identical in design to Ranger 3, with the same impact-limiter – made of balsa wood! – atop the lunar capsule. Ranger 4 went through preliminary testing with flying colours, the first of the Rangers to do so. However the mission itself was a disaster, as the on-board computer failed, and no useful data was returned and none of the preprogrammed actions, such as solar power deployment and high-gain antenna utilisation, took place. Ranger 4 finally impacted the far side of the Moon on 26 April 1962, becoming the first US craft to land on another celestial body. Ranger 5 was launched in October 1962 at a time when NASA was under pressure due to the many failures and technical problems, not only with the Ranger missions, but with the Mariner missions, Mariner 1 (designed for a flyby mission to Venus) having been a conspicuous disaster. Unfortunately Ranger 5 didn’t improve matters, with a series of on-board and on-ground malfunctions. The craft missed the Moon by a mere 700 kilometres. Ranger 6, launched well over a year later, was another conspicuous failure, as its sole mission was to send high-quality photos of the Moon’s surface before impact. Impact occurred, and overall the flight was the smoothest one yet, but the camera system failed completely.
There were three more Ranger missions. Ranger 7, launched in July 1964, was the first completely successful mission of the series. Its mission was the same as that of Ranger 6, but this time over 4,300 photos were transmitted during the final 17 minutes of flight. These photos were subjected to much scrutiny and discussion, in terms of the feasibility of a soft landing, and the general consensus was that some areas looked suitable, though the actual hardness of the surface couldn’t be determined for sure. Miraculously enough, Ranger 8, launched in February 1965, was also completely successful. Again its sole mission was to photograph the Moon’s surface, as NASA was beginning to ready itself for the Apollo missions. Over 7,000 good quality photos were transmitted in the final 23 minutes of flight. The overall performance of the spacecraft was hailed as ‘excellent’, and its impact crater was photographed two years later by Lunar Orbiter 4. And finally Ranger 9 made it three successes in a row, and this time the camera’s 6,000 images were broadcast live to viewers across the United States. The date was March 24, 1965. The next step would be that giant one.
I’ve just had my first ever conversation with someone who at least appears to be sceptical of the Apollo 11 moon landing of 1969 – and, I can only suppose, the five subsequent successful moon landings. Altogether, twelve men walked on the moon between 20 July 1969 and December 10 1972, when the crew members of Apollo 17 left the moon’s surface. Or so the story goes.
This conversation began when I said that perhaps the most exciting world event I’ve experienced was that first moon landing, watching Neil Armstrong possibly muffing the lines about one small step for a man, and marvelling that it could be televised. I was asked how I knew that it really happened. How could I be so sure?
Of course I had no immediate answer. Like any normal person, I have no immediate, or easy, answer to a billion questions that might be put to me. We take most things on trust, otherwise it would be a very very painstaking existence. I didn’t mention that, only a few months before, I’d read Phil Plait’s excellent book Bad Astronomy, subtitled Misconceptions and misuses revealed, from astrology to the moon landing ‘hoax’. Plait is a professional astronomer who maintains the Bad Astronomy blog and he’s much better equipped to handle issues astronomical than I am, but I suppose I could’ve made a fair fist of countering this person’s doubts if I hadn’t been so flabbergasted. As I said, I’d never actually met someone who doubted these events before. In any case I don’t think the person was in any mood to listen to me.
Only one reason for these doubts was offered. How could the lunar module have taken off from the moon’s surface? Of course I couldn’t answer, never having been an aeronautical engineer employed by NASA, or even a lay person nerdy enough to be up on such matters, but I did say that the moon’s minimal gravity would presumably make a take-off less problematic than, say, a rocket launch from Mother Earth, and this was readily agreed to. I should also add that the difficulties, whatever they might be, of relaunching the relatively lightweight lunar modules – don’t forget there were six of them – didn’t feature in Plait’s list of problems identified by moon landing skeptics which lead them to believe that the whole Apollo adventure was a grand hoax.
So, no further evidence was proffered in support of the hoax thesis. And let’s be quite clear, the claim, or suggestion, that the six moon landings didn’t occur, must of necessity be a suggestion that there was a grand hoax, a conspiracy to defraud the general public, one involving tens of thousands of individuals, all of whom have apparently maintained this fraud over the past 50 years. A fraud perpetrated by whom, exactly?
My conversation with my adversary was cut short by a third person, thankfully, but after the third person’s departure I was asked this question, or something like it: Are you prepared to be open-minded enough to entertain the possibility that the moon landing didn’t happen, or are you completely closed-minded on the issue?
Another way of putting this would be: Why aren’t you as open-minded as I am?
So it’s this question that I need to reflect on.
I’ve been reading science magazines on an almost daily basis for the past thirty-five years. Why?
But it didn’t start with science. When I was kid, I loved to read my parents’ encyclopaedias. I would mostly read history, learning all about the English kings and queens and the battles and intrigues, etc, but basically I would stop at any article that took my fancy – Louis Pasteur, Marie Curie, Isaac Newton as well as Hitler, Ivan the Terrible and Cardinal Richelieu. Again, why? I suppose it was curiosity. I wanted to know about stuff. And I don’t think it was a desire to show off my knowledge, or not entirely. I didn’t have anyone to show off to – though I’m sure I wished that I had. In any case, this hunger to find things out, to learn about my world – it can hardly be associated with closed-mindedness.
The point is, it’s not science that’s interesting, it’s the world. And the big questions. The question – How did I come to be who and where I am? – quickly becomes – How did life itself come to be? – and that extends out to – How did matter come to be? The big bang doesn’t seem to explain it adequately, but that doesn’t lead me to imagine that scientists are trying to trick us. I understand, from a lifetime of reading, that the big bang theory is mathematically sound and rigorous, and I also know that I’m far from alone in doubting that the big bang explains life, the universe and everything. Astrophysicists, like other scientists, are a curious and sceptical lot and no ‘ultimate explanation’ is likely to satisfy them. The excitement of science is that it always raises more questions than answers, it’s the gift that keeps on giving, and we have human ingenuity to thank for that, as we’re the creators of science, the most amazing tool we’ve ever developed.
But let me return to open-mindedness and closed-mindedness. During the conversation described above, it was suggested that the USA simply didn’t have the technology to land people on the moon in the sixties. So, ok, I forgot this one: two reasons put forward – 1, the USA didn’t have the technological nous; 2, the modules couldn’t take off from the moon (later acknowledged to be not so much of an issue). I pretty well knew this first reason to be false. Of course I’ve read, over the years, about the Apollo missions, the rivalry with the USSR, the hero-worship of Yuri Gagarin and so forth. I’ve also absorbed, in my reading, much about spaceflight and scientific and technological development over the years. Of course, I’ve forgotten most of it, and that’s normal, because that’s how our brains work – something I’ve also read a lot about! Even the most brilliant scientists are unlikely to be knowledgeable outside their own often narrow fields, because neurons that fire together wire together, and it’s really hands-on work that gets those neurons firing.
But here’s an interesting point. I have in front of me the latest issue of Cosmos magazine, issue 75. I haven’t read it yet, but I will do. On my shelves are the previous 74 issues, each of which I’ve read, from cover to cover. I’ve also read more than a hundred issues of the excellent British mag, New Scientist. The first science mag I ever read was the monthly Scientific American, which I consumed with great eagerness for several years in the eighties, and I still buy their special issues sometimes. Again, the details of most of this reading are long forgotten, though of course I learned a great deal about scientific methods and the scientific mind-set. The interesting point, though, is this. In none of these magazines, and in none of the books, blogs and podcasts I’ve consumed in about forty years of interest in matters scientific, have I ever read the claim, put forward seriously, that the moon landings were faked. Never. I’m not counting of course, books like Bad Astronomy and podcasts like the magnificent Skeptics’ Guide to the Universe, in which such claims are comprehensively debunked.
Scientists are a skeptical and largely independent lot, no doubt about it, and I’ve stated many times that scepticism and curiosity are the twin pillars of all scientific enquiry. So the idea that scientists could be persuaded, or cowed into participating in a conspiracy (at whose instigation?) to hoodwink the public about these landings is – well let’s just call it mildly implausible.
But of course, it could explain the US government’s massive deficit. That’s it! All those billions spent on hush money to astronauts, engineers, technicians (or were they all just actors?), not to mention nosey reporters, science writers and assorted geeks – thank god fatty Frump is here to make America great again and lift the lid on this sordid scenario, like the great crusader against fake news that he is.
But for now let’s leave the conspiracy aspect of this matter aside, and return to the question of whether these moon landings could ever have occurred in the late sixties and early seventies. I have to say, when it was put to me, during this conversation, that the technology of the time wasn’t up to putting people on the moon, my immediate mental response was to turn this statement into a question. Was the technology of the time up to it? And this question then turns into a research project. In other words, let’s find out, let’s do the research. Yay! That way, we’ll learn lots of interesting things about aeronautics and rocket fuel and gravitational constraints and astronaut training etc, etc – only to forget most of it after a few years. Yet, with all due respect, I’m quite sure my ‘adversary’ in this matter would never consider engaging in such a research project. She would prefer to remain ‘open-minded’. And if you believe that the whole Apollo project was faked, why not believe that all that’s been written about it before and since has been faked too? Why believe that the Russians managed to get an astronaut into orbit in the early sixties? Why believe that the whole Sputnik enterprise was anything but complete fakery? Why believe anything that any scientist ever says? Such radical ‘skepticism’ eliminates the need to do any research on anything.
But I’m not so open-minded as that, so in my dogmatic and doctrinaire fashion I will do some – very limited – research on that very exciting early period in the history of space exploration. I’ll report on it next time.
Quote of the day/week/month/post:
Better to have questions you can’t answer than answers you can’t question – Max Tegmark (and many others)
Jacinta: So while astrophysicists argue over the likelihood of life elsewhere in our tiny but massive universe, some are focusing on our nearest star neighbour. Some wobbling of the red dwarf known as Proxima Centauri has revealed, upon lengthy observation, that it has a closely orbiting planet, which considering the relative coolness of the star – way too dim to be seen with the naked eye – and the proximity of its satellite, is very much in the habitable zone. While it’s too early to say so much for the naysayers, the discovery of a planet in the Goldilocks zone of our nearest star in a galaxy of billions of possibilities must surely raise hopes and expectations of life abundant.
Canto: This closest possible exoplanet was only discovered in August this year, so we’re desperate to find out more about it. Being in the habzone is one thing, habitability is another. Obvious questions we have no current way of answering are: does it have an atmosphere? Any possibility of water? Is it tidally locked? And of course we’d love to know if we could launch some sort of robotic mission to our nearest star neighbour. Meanwhile is there any other way of gleaning more info from this tantalising object?
Jacinta: It’s not likely to be habitable though. Solar winds are estimated to be some 2000 times those experienced on Earth, though we can’t be too sure. Researchers are trying to work out the size of the planet…
Canto: How do they know about those solar winds?
Jacinta: Oooh, that’s a horribly good question. It’s due to the closeness of the orbit, where you would expect the solar winds to be much stronger, as they are in our solar system. It’s believed that Mercury’s magnetic field, which should be stronger than it’s been measured to be because of its heavy metallic core, is dampened massively by our solar wind. So basically they would’ve inferred Proxima Centauri’s wind by our own. As to how they came up with the figure of 2000 times that experienced on Earth, I’ve no idea, but strong solar winds make it hard to maintain an atmosphere, which is vital for life. You’ve also talked about tidal locking, which is a feature of close orbits, such as the Moon’s orbit of the Earth. So you’ll have a permanently hot day side and a permanently cool night side, and this can be problematic for the creation of an atmosphere, according to modelling.
Canto: Now, all of this sounds very negative, but basing exo-planetary activity on what’s been the case, as far as we can work it out, in our solar system, has been really problematic hasn’t it?
Jacinta: Definitely, that’s why we need to go beyond modelling, if we can, and collect some real data. So we’re looking to the James Webb Space Telescope (JWST), the very exciting successor to Hubble to be launched around November 2018, to garner more info, which it’ll be perfectly equipped to do.
Canto: If by some near-miraculous combination of circs there is an atmosphere on Proxima b, or a reasonable quantity of liquid water, that would help distribute the heat around the planet. With no atmosphere, the difference between day side and night side would be stark.
Jacinta: Exactly, and that’s what the JWST should be able to detect, as the best way to detect the atmosphere is to measure the planet’s infrared heat signature. If the JWST finds a decisive and fixed difference between the planet’s day and night sides, it’s a safe bet that no atmosphere is present. The JWST will be equipped to measure this IR signature on both sides of the planet, and if it doesn’t find that stark difference, that’ll be when we can start speculating about an atmosphere and its constituents.
Canto: Though of course they’ve already started with the speculation. But really, whatever they find – and I don’t expect that everything will line up for life – the fact that we’ve found an exoplanet well worth investigating on the nearest star outside our solar system, with billions of stars yet to be homed in on, one by one – doesn’t that say something to those who argue for the Fermi paradox – where are they? Okay, Fermi and Hart were talking about intelligent life, and that may well be orders of magnitude more difficult to develop than life itself, but I’m sure that Fermi would be unsettled in his skepticism, if he was alive today, by the vast numbers of exoplanets, in other words possibilities for life, we’re discovering now, with so many to come in the near future.
Jacinta: Yes, bliss in this time it is to be alive, but to be young, that would be very heaven!
Cosmos issue 71, pp9-10
Canto: So we’ve talked all too briefly about Earth’s probable formation and how its moon was formed some fifty million years later, and I’m not sure whether I want to go back further in time to try to answer some big questions about the solar system in general or the solar nebula, or forward to consider how life emerged from inanimate matter on this seething-hot, volatile planetary surface…
Jacinta: Well since we’re the blind leading the blind, it doesn’t much matter which direction we go. Let’s choose life.
Canto: Okay, but we’ll have a way to travel before we get there.
Jacinta: Well most of us learned at school that the Earth has a crust, a mantle and a core, and that the core is of iron and it’s really hot down there, and the crust is formed of plates that move around and go under each other, and that the atmosphere above the crust consists of layers, like the stratosphere and the ionosphere, and the atmosphere around us is around three-quarters nitrogen and a quarter oxygen with traces of other gases, and if it wasn’t like that we wouldn’t be here. But it wasn’t anything like that when the first life appeared.
Canto: Yes, it was very different, and it seems there’s more that we don’t know about the period between 4.5 and 4 billion BP than there is that we do know, if you know what I mean.
Canto: Before the Present. I got that from the excellent Stuff You Should Know podcast, and I’m going to use it from now on.
Jacinta: D’accord. So yes, we know that the early Earth was incredibly hot, reaching temperatures of 2000 celsius or more, but there’s also evidence from ancient amphibolite rocks and banded iron formations that there was water on the Earth, and plenty of it, 4.3 billion years ago. Which suggests an extraordinarily fast cooling down period, and where did all that water come from?
Canto: Yes I think we really need to look at this period, or what we know of it, to try and make sense of it, because it doesn’t quite make sense to me. A hot magma world, melted fom the inside out, but also bombarded from the outside by meteorites, then after the bombardment suddenly cooling from the outside in, and flowing with water. All in a couple of hundred million years?
Jacinta: That’s a long time actually. We’re hoping to live for a hundred years for some strange reason – a two millionth of our time-frame, if we’re very lucky.
Canto: Well it’s all relative, but where did this water come from? Some say it must’ve come from space, because that’s all that happened, meteors from out there crashing into here. Where else could it come from?
Jacinta: How do you trap water here when the surface temperature is so high? Water boils at 100c, right?
Canto: Under ‘normal’ atmospheric pressure. The early Earth was anything but normal.
Jacinta: Anyway it just doesn’t seem possible to get so much water from rocks crashing into us. There’s another alternative – the water was already here. So the original bits and pieces that formed the Earth – carbonaceous chondrites or whatever – contained water and this water somehow made its way to the surface.
Canto: Somehow. Leaving aside the rising-to-the-surface problem, carbon-rich chondrites are found in asteroids today, and they have apparently a similar water-plus-impurities ratio to our oceanic water, and that’s obviously very suggestive.
Jacinta: Yes and the isotopic ratios pretty well match, but they don’t for comets. Scientists have been able to measure the isotopic ratios in comets such as Halley and Hale-Bopp, and they don’t have anything like the proportions found in our oceans. I’m talking heavy water here, deuterium, but also protium which is another isotope of hydrogen.
Canto: NASA also launched a spacecraft, Deep Impact, to probe the constituents of a comet, Tempel1, and the results were negatory for its candidature as feeder of the Earth’s water, had it ever landed here, but of course not nugatory for astronomical research generally. But then, what comet is ever typical? Anyway, there’s a just-so story, sort of, that I watched on video recently, which explained the oceans, sort of. It told us that the planetesimals that created the Earth contained water locked inside, and that years of later volcanic activity released that water to the surface as steam, which condensed in the cool upper atmosphere and fell as rain. And the rain it rainèd every day.
Jacinta: So the Bible was right then?
Canto: More than forty days and nights – thousands of years, they claimed. But that made up only half the world’s oceans. The rest came from comets, they said. Now that seems unlikely, but replace comets with the right sorts of asteroids, and the recipe still works.
Jacinta: Well here’s another story, which is meant to explain how that heat-creating heavy bombardment came to an end. The Earth’s bombarded surface was extremely hot, melting everything, even the rocks, and in this state the heavier elements such as iron sank to the centre, forming our core, which was vital in protecting us from the notorious solar wind – that incredibly strong force that has blown away the atmosphere of Mars.
Canto: Yeah, they say it kind of magnetised the Earth, and that was like a shield of steel.
Jacinta: Aka the magnetosphere, but I’m afraid that electromagnetism was a subject that transformed me into a gibbering mass of incomprehension at school.
Canto: I can’t say I understand it myself, but the magnetosphere works to almost perfectly preserve our atmosphere. We do lose a percentage to the solar wind every year but it’s so tiny that it’s not a problem. Another anthropic circumstance that proves the existence of God.
Jacinta: Hallelujah. So did this magnetosphere form before or after the formation of the moon?
Canto: God knows.
Canto: Sorry princess.
Jacinta: Princess, goddess, actress, countess, diminutives. They diminish.
Canto: Watercress. Anyway it probably happened around the same time. The great crash that probably created the moon has been nicely computer-simulated by Robin Canup of the Southwest Research Institute – it’s well worth a look. The theory goes that this great glancing blow tilted the Earth and gave us our seasons, probably vital to life as we know and love it.
Jacinta: Yes but it would’ve heated up the planet even more, so I’m interested in the problem of the shift from this to our amphibolite rocks under water from nearly 4.3 billion years ago. Where the eff did that water come from? It steamed up from beneath the surface? Not likely. And from asteroids? Really?
Canto: Possibly. But according to this excellent Naked Science video, the best-preserved meteorites ever recovered came from a landfall in British Columbia in 2000. And when they investigated this meteorite material they found that it was made up of 20% water by weight, and that’s pretty significant…
Jacinta: Because water isn’t dense like rock is it, so that sounds like a lot of water. We’re learning a lot from this video, such as that meteorites don’t cause great fireballs or anything like that, because they’ve been tumbling about in cold space for eons, and their entry into the Earth’s atmosphere only heats up a few millimetres of the outer surface, and then only for a very brief period, so they pretty well instantly go cold again.
Canto: Right and maybe that explains something else; that a heavy bombardment of these big wet boulders – and apparently they’ve found that the further they are from us, the more water they contain – would’ve cooled the planet.
Jacinta: Interesting idea, which I’m sure someone’s thought of and maybe even computer modelled. Certainly it would help to explain the apparent speed with which the oceans were formed. So… I’m not really convinced, but in lieu of a better explanation I’ll take it on trust that the oceans were created in little more than a million years or so by a hailstorm of asteroids, together with water steamed up from below the surface. So now we have a somewhat cooler Earth, ready at last for some kind of life, but not as we experience it.
Canto: Right, we’re talking about an atmosphere containing virtually no oxygen. Made up mostly of nitrogen, carbon dioxide and methane.
Jacinta: And how do they know that? I’ve also heard hydrogen sulphide mentioned.
Canto: Yeah, upwellings from volcanic activity I believe.
Jacinta: So the stage is set for some sort of proto-life, with RNA or some precursor. And so the fun begins, if it hasn’t already.
Canto: Indeed it does. So that’s what we’ll be exploring next. I’ve even heard some researchers claim that water isn’t necessary for basic life to get started. Now there’s heresy for you.
Jacinta: That’s the fun of heresy these days, you don’t get burned alive for it, no more than a bit of gentle ribbing. I’m looking forward to the next post.
Jacinta: I’d like to know how we got in this position.
Canto: What position?
Jacinta: Here, on Earth.
Canto: That’s a very long story, which I suspect nobody’s really qualified to tell. But maybe we can report on the best speculations. First, in order to understand how we got here we have to understand how the Earth got here.
Jacinta: And so on, infinitely regressing. So let’s just start with the Earth.
Canto: Needless to say we don’t know all the details and there are doubtless competing theories, and new data is being regularly uncovered, but it obviously has to do with how our entire solar system was formed.
Jacinta: I’ve heard that all the heavy metals like iron and whatnot are forged within stars, like when they go supernova, but our star hasn’t done that, all it seems to produce is light, yet Earth is full of heavy elements. I really don’t get it.
Canto: I recall reading years ago a theory that the Earth was formed from an accretion of planetesimals, little planets…
Canto: Yes, but how those little things came into being themselves I’m not sure.
Jacinta: Well we have lots of rocky bits and bobs called asteroids floating about in the solar system…
Canto: Yes, but not randomly. there’s a whole big asteroid belt between Jupiter and Mars, where they’re coralled, sort of.
Jacinta: But comets are different, they seem to have their individual eccentric orbits.
Canto: I suppose the point is that they also have heavy elements, and how were those elements formed?
Jacinta: Heat and pressure, I’m guessing, so things must’ve been hugely different in earlier times.
Canto: Well, this BBC site gives us some of the latest speculations. They reckon that the Earth probably formed from planetesimals, so that’s still the best hypothesis it seems, though it’s very light on details:
The Earth is thought to have been formed about 4.6 billion years ago by collisions in the giant disc-shaped cloud of material that also formed the Sun. Gravity slowly gathered this gas and dust together into clumps that became asteroids and small early planets called planetesimals.
Jacinta: Yes, that’s extremely vague. How do they know there was a disc-shaped cloud here? How can they investigate that far back?
Canto: Well don’t forget that looking out over huge distances means looking back in time.
Jacinta: Yes but a huge distance away isn’t here. Is it?
Canto: Well it might be here then.
Jacinta: Effing Einstein. But they’re also searching for extra data on the past, like checking out meteorites, which might contain material older than anything on Earth. Can they reliably date material that’s say, 5 billion years old? The Earth’s only about 4.5 billion years old, right?
Canto: I think 4.6 billion, give or take a few minutes. About a third of the age of the universe. And here’s the thing, we’ve dated all the meteorites and asteroids we can get to and they’re all round the same age, within a narrow range of a few hundred million years. So our date for the beginnings of the solar system is the oldest date for these floating and landing rocks, which is also our date for the Earth, about 4.6 billion.
Jacinta: So is our dating system completely accurate, and what by the way are carbonaceous chondrites?
Canto: Well, yes, radioactive decay provides a very accurate clock, and these meteorites have radioactive material in them, just as the core of our planet does. All the evidence so far suggests that things happened very quickly, in terms of accretion and formation of planets, once all this heavy and radioactive material was created. Carbonaceous chondrites are a type of meteorite. They’re amongst the oldest meteorites but relatively rare – they make up less than 5% of our meteorites. I mean the ones that land here. Why do you ask?
Jacinta: I’ve heard about them as being somehow important for research, and maybe dating?
Canto: Well there are different types of C chondrites as they’re called, and some of them, most interesting to us of course, are rich in organic compounds and water. This fact apparently shows that they haven’t been subjected to high temperatures, unlike for example the early Earth. But let me return to that BBC quote above. The theory goes that a supernova explosion, or maybe more than one, created all the heavy elements we have now – iron, carbon, silver, gold, uranium and all the rest, heat and pressure as you say, and these elements swirled around but were gravitationally attracted to a centre, which evolved into our sun. This was the spinning disc-shaped cloud mentioned above, known as the solar nebula.
Jacinta: Would you call that a theory, or a hypothesis, or wild desperate speculation?
Canto: I’d call it ‘the best we can do at the present moment’. But be patient, it’s a great time to be young in astronomy today. What we need is data, data, data, and we’re just starting to collect more data than we can rightly deal with on planets within and especially outside our solar system. Kepler’s just the beginning, girlie.
Jacinta: Je suis tout à fait d’accord, boyo. I think many of the astrophysicists are looking forward to having their cherished models swept aside by all the new telescopes and spectroscopes and what else and the data they spew back to Earth.
Canto: Uhh, well anyway let’s get back to our ‘best scenario for the moment’ scenario. So you have all this matter spinning around and the force of gravity causes accretion. It’s a messy scenario actually because everything’s moving at different velocities and angular momentums if that’s a thing, upwards, forwards, sideways down, and sometimes there’s accretion, sometimes fragmentation, but overall the movement is towards coalescence due to gravity. Particles grow to the size of monuments and then different sized planetesimals, fewer and bigger and farther between. And the smaller, gaseous elements are swept out by the solar wind into the great beyond, where they accrete into gas giants.
Jacinta: Right, but isn’t the data from Kepler and elsewhere already starting to play havoc with this scenario? Gas giants within spitting distance of their suns and the like?
Canto: Well, you need liquid to spit, but maybe you have a point, but I think it’s wise not to be too distracted by exoplanets and their systems at this stage. I think we need to find an internally coherent and consistent account of our own system.
Jacinta: What about the Juno probe, will that help?
Canto: Well I’m sure it will help us learn more about gas giants, but let’s just focus on the Earth now.
Jacinta: Okay, stay focussed.
Canto: These larger planetesimals became bigger gravitational attractors, each accumulating matter until we had four rocky planets in different, sufficiently distant orbits around their sun.
Jacinta: Oh yes, and what about the moons? Why didn’t they coalesce as neatly as all the other minor rocky bits?
Canto: Mmmm, well there’s nothing neat about all this, but mmmm…
Jacinta: How many moons are there?
Canto: For the inner planets? Only three, ours and two for Mars. So the question is, how come some of those rocks, or at least three, didn’t get stuck to the bigger rocks i.e. planets, via gravity, but instead started circling those planets, also due to gravity.
Jacinta: Yes, which might be the same question as why do the planets orbit around this massive gravitational attractor, the sun, instead of getting sucked into it, like what happens with those supermassive supersucking black holes?
Canto: Well first let me talk about our moon, because the most currently accepted theory about how our moon came into existence might surprise you.
Jacinta: It was a lot closer to the Earth at the beginning, wasn’t it? So it’s slowly spiralling away from us?
Canto: Yes. Tidal forces. The moon’s tidally locked to the Earth, it’s the same face she shows us always, but let’s keep on track, it was formed in the very early days, when things were still very chaotic. A pretty large planetesimal, or planetoid, slammed into Earth, which was somewhat smaller then, and it stuck to it and coalesced with it – the Earth was pretty-well molten in those days – and a lot of debris was thrown out into space, but this debris didn’t quite escape Earth’s gravitational field, instead it coalesced to form our moon. This theory was first put forward a few decades ago, after moon rocks brought back from the Apollo missions were found to be younger than the oldest Earth rocks, and composed of much the same stuff, which came as a great surprise. But now the theory is well accepted, as it accounts for a number of other factors in the relationship between the two bodies.
Jacinta: Okay, so is that it on how the Earth was formed?
Canto: Well, yes, but the bigger question is your original one – how did we get here. And that means we have to look at how life got started here. Because we’re only up to about 4.5 billion years ago – with the moon being formed about 50 million years after the Earth. And at that point the Earth was like a sea of hot magma, hot from all the collisions on the surface, and hot from the radiation bursting out from its core. Hardly great conditions for life.
Jacinta: Well there might’ve been life, but not as we know it boyo.
Canto: I’m skeptical, but we’ll talk about that next time.
Jacinta: Well Canto I’d like to get back to Einstein and space and time and the cosmos, just because it’s such a fascinating field to inhabit and explore.
Canto: Rather a big one.
Jacinta: I’ve read, or heard, that Einstein’s theory, or one of them, predicted black holes, though he didn’t necessarily think that such entities really existed, but now black holes are at the centre of everything, it seems.
Canto: Including our own galaxy, and most others.
Jacinta: Yes, and there appears to be a correlation between the mass of these supermassive black holes at the centres of galaxies and the mass of the galaxies themselves, indicating that they appear to be the generators of galaxies. Can you expand on that?
Canto: Well the universe seems to be able to expand on that better than I can, but I’ll try. Black holes were first so named in the 1960s, but Einstein’s theory of general relativity recast gravity as a distortion of space and time rather than as a Newtonian force, with the distortion being caused by massive objects. The greater the mass, the greater the distortion, or the ‘geodetic effect’, as it’s called. The more massive a particular object, given a fixed radius, the greater is the velocity required for an orbiting object to escape its orbit, what we call its escape velocity. That escape velocity will of course, approacher closer and closer to the speed of light, as the object being orbited becomes more massive. So what happens when it reaches the speed of light? Then there’s no escape, and that’s where we enter black hole territory.
Jacinta: So, let me get this. Einstein’s theory is about distortions of space-time (and I’m not going to pretend that I understand this), or geodetic effects, and so it has to account for extreme geodetic effects, where the distortion is so great that nothing, not even light, can escape, and everything kind of gets sucked in… But how do these massive, or super-massive objects come into being, and won’t they eventually swallow all matter, so that all is just one ginormous black hole?
Canto: Okay I don’t really get this either but shortly after Einstein published his theory it was worked out by an ingenious astrophysicist, Karl Schwarzschild – as a result of sorting out Einstein’s complex field equations – that if matter is severely compressed it will have weird effects on gravity and energy. I was talking a minute ago about increasing the mass, but think instead of decreasing the radius while maintaining the mass as a constant…
Jacinta: The same effect?
Canto: Well, maybe, but you’ll again reach a point where there’s zero escape, so to speak. In fact, what you have is a singularity. Nothing can escape from the object’s surface, whether matter or radiation, but also you’ll have a kind of internal collapse, in which the forces that keep atoms and sub-atomic particles apart are overcome. It collapses into an infinitesimal point – a singularity. It was Schwarzschild too who described the ‘event horizon’, and provided a formula for it.
Jacinta: That’s a kind of boundary layer, isn’t it? A point of no return?
Canto: Yes, a spherical boundary that sort of defines the black hole.
Jacinta: So why haven’t I heard of this Schwarzschild guy?
Canto: He died in 1916, shortly after writing a paper which solved Einstein’s equations and considered the idea of ‘point mass’ – what we today would call a singularity. But both he and Einstein, together with anyone else in the know, would’ve considered this stuff entirely theoretical. It has only become significant, and very significant, in the last few decades.
Jacinta: And doesnt this pose a problem for Einstein’s theory? I recall reading that this issue of ‘point mass’, or a situation where gravity is kind of absolute, like with black holes and the big bang, or the ‘pre-big bang’ if that makes sense, is where everything breaks down, because it seems to bring in the mathematical impossibility of infinity, something that just can’t be dealt with mathematically. And Einstein wasn’t worried about it in his time because black holes were purely theoretical, and the universe was thought to be constant, not expanding or contracting, just there.
Canto: Well I’ve read – and I dont know if it’s true – that Einstein believed, at least for a time, that black holes couldn’t actually exist because of an upper limit imposed on the gravitational energy any mass can produce – preventing any kind of ‘infinity’ or singularity.
Jacinta: Well if that’s true he was surely wrong, as the existence of black holes has been thoroughly confirmed, as has the big bang, right?
Canto: Well of course knowledge was building about that in Einstein’s lifetime, as Edwin Hubble and others provided conclusive evidence that the universe was expanding in 1929, so if this expansion was uniform and extended back in time, it points to an early much-contracted universe, and ultimately a singularity. And in fact Einstein’s general relativity equations were telling him that the universe wasn’t static, but he chose to ignore them, apparently being influenced by the overwhelming thinking of the time – this was 1917 – and he introduced his infamous or famous cosmological constant, aka lambda.
Jacinta: And of course 1917 was an early day in the history of modern astronomy, we hardly knew anything beyond our own galaxy.
Canto: Or within it. One of the great astrophysicists of the era, Sir Arthur Eddington, believed at the time that the sun was at the centre of the universe, while admitting his calculations were ‘subject to large uncertainties’.
Jacinta: Reminds me of Lord Kelvin on the age of the Earth only a few generations before.
Canto: Yes, how quickly our best speculations can become obsolete, but that’s one of the thrills of science. And it’s worth noting that the work of Hubble and others on the expansion of the universe depended entirely on improved technology, namely the 100-inch Hooker telescope at Mount Wilson, California.
Jacinta: Just as the age of the Earth problem was solved through radiometric dating, which depended on all the early twentieth century work on molecular structure and isotopes and such.
Canto: Right, but now this lambda (λ) – which Einstein saw as a description of some binding force in gravity to counteract the expansion predicted by his equations – is very much back in the astrophysical frame. The surprising discovery made in 1998 that the universe’s expansion is accelerating rather than slowing has, for reasons I can’t possibly explain, brought Einstein’s lambda in from the cold as an explanatory factor in that discovery, which is also somehow linked to dark energy.
Jacinta: So his concept, which he simply invented as a ‘fix-it’ sort of thing, might’ve had more utility than he knew?
Canto: Well the argument goes, among some, that Einstein was a scientist of such uncanny insight that even his mistakes have proved more fruitful than others’ discoveries. Maybe that’s hero worship, maybe not.
Jacinta: So how does lambda relate to dark energy, and how does dark energy relate to dark matter, if you please?
Canto: Well the standard model of cosmology (which is currently under great pressure, but let’s leave that aside) has been unsuccessful in trying to iron out inconsistent observations and finding with regard to the energy density of the universe, and so dark energy and what they call cold dark matter (CDM) have been posited as intellectual placeholders, so to speak, to make the observations and equations come out right.
Jacinta: Sounds a bit dodgy.
Canto: Well, time will tell how dodgy it is but I don’t think anyone’s trying to be dodgy, there’s a great deal of intense calculation and measurement involved, with so many astrophysicists looking at the issue from many angles and with different methods. Anyway, to quickly summarise CDM and dark energy, they together make up some 96% of the mass-energy density of our universe according to the most currently accepted calculations, with dark energy accounting for some 69% and CDM accounting for about 27%.
Jacinta: Duhh, that does sound like a headachey problem for the standard model. I mean, I know I’m only a dilettanty lay-person, but a model of universal mass-energy that only accounts for about 4% of the stuff, that doesn’t sound like much of a model.
Canto: Well I can assure they’re working on it…
Jacinta: Or working to replace it.
Canto: That too, but let me try to explain the difference between CDM and dark energy. Dark energy is associated with lambda, because it’s the ‘missing energy’ that accounts for the expansion of the universe, against the binding effects of gravity. As it happens, Einstein’s cosmological constant pretty well perfectly counters this expansive energy, so that if he hadn’t added it to his equations he would’ve been found to have predicted an expanding universe decades before this was confirmed by observation. That’s why it was only in the thirties that he came to regret what he called the greatest mistake of his career. Cold dark matter, on the other hand, has been introduced to account for a range of gravitational effects which require lots more matter than we find in the observed (rather than observable) universe. These effects include the flat shapes of galaxies, gravitational lensing and the tight clustering of galaxies. It’s described as cold because its velocity is considerably less than light-speed.
Jacinta: Okay, so far so bad, but let’s get back to black holes. Why are they so central?
Canto: Well, that’s perhaps the story of supermassive black holes in particular, but I suppose I should try to tell the story of how astronomers found black holes to be real. As I’ve said, the term was first used in the sixties, 1967 to be precise, by John Wheeler, at a time when their actual existence was being considered increasingly likely, and the first more or less confirmed discovery was made in 1971 with Cygnus x-1. You can read all about it here. It’s very much a story of developing technology leading to increasingly precise observational data, largely in the detecting and measuring of X-ray emissions, stuff that was undetectable to us with just optical instruments.
Jacinta: Okay, go no further, I accept that there’s been a lot of data from a variety of sources that have pretty well thoroughly confirmed their existence, but what about these supermassive black holes? Could they actually be the creators of matter in the galaxies they’re central to? That’s what I’ve heard, but my reception was likely faulty.
Canto: Well astrophysicists have been struggling with the question of this relationship – there clearly is a relationship between supermassive black holes and their galaxies, but which came first? Now supermassive black holes can vary a lot – our own ‘local’ one is about 4 million solar masses, but we’ve discovered some with billions of solar masses. But it was found almost a decade ago that there is correlation between the mass of these beasties and the mass of the inner part of the galaxies that host them – what they call the galactic bulge. The ratio is always about 1 to 700. Obviously this is highly suggestive, but it requires more research. There are some very interesting examples of active super-feeding black holes emitting vast amounts of energy and radiation, which is both destructive and productive in a sense, creating an active galaxy. Our own Milky Way, or the black hole at its centre, is currently quiescent, which is just as well.
Jacinta: You mean if it starts suddenly feeding, we’re all gonna die?
Canto: No probably not, the hole’s effects are quite localised, relatively speaking, and we’re a long way from the centre.
Jacinta: Okay thanks for that, that’s about as much about black holes as I can stand for now.
Canto: Well I’m hoping that in some future posts we can focus on the technology, the ground-based and space-based telescopes and instruments like Hubble and Kepler and James Webb and so many others that have been enhancing our knowledge of black holes, other galaxies, exoplanets, all the stuff that makes astrophysics so rewarding these days.
Jacinta: You’re never out of work if you’re an astrophysicist nowadays, so I’ve heard. Halcyon days.