In the early phase of the young, expanding universe, the primordial atoms of hydrogen, some helium, and traces of lithium were present in strings and clumps. These structures go back to the very earliest times. The cosmic microwave background hints at such structures very early on, and on the most enormous scales of astronomy they also put in an appearance. Strings and clusters of galaxies are visible everywhere, with vast voids between them where there seems to be nothing at all.
Gravity, although it’s by far the weakest of the fundamental fields, acts over enormous distances. Because of this, the tiniest fluctuations in density in the early universe have become the very largest structures we are aware of. Galaxies and clusters of galaxies began as truly enormous volumes of tenuous gas. And just as tiny density fluctuations became concentrations and voids, so imperceptible movements became enormous swirls, rotations and flows under the relentless action of gravity. Loose accumulations became ever tighter concentrations; gentle drifting became powerful vortices.
This happened at every conceivable scale. When a volume of gas is compressed by its own gravity, it doesn’t remain spherical. Rotation of the mass increases as the material is pulled together and the end result is inevitably a disk rotating slowly at the outer edge, but ever faster towards the centre. This is how proto-galaxies formed. And within those proto-galaxies, the same process on a far smaller scale allowed stars to form – but that’s another story.
For now, just ponder the fact that galaxy clusters and galaxies are emergent features given the gravitational field that permeates the universe and sufficiently large amounts of gas.
The gap has been closing little by little from both the astronomical and biological sides. But though it’s narrower now than ever before, it’s still a gap.
How did life begin? It seems possible, even very likely, that simple chemistry has the potential to generate life given the right conditions and plenty of time.
There’s always been a big puzzle over the origin of life here on Earth. Life is everywhere and in a vast array of forms. From the simplest archaea and bacteria, to the giant redwood and the humble grass in the field, the blue whale down to the smallest mite. So rich in variety, so wide in its presence from the deepest oceans to the highest mountains. Life is amazing!
The processes of evolution are well understood and impossible to deny; so puzzles over the many forms of life, its adaptability, and changes in the forms we see coming and going over deep time are clearly understood and well explained by biologists. (When did you last see a dinosaur?)
But how did it all start?
Ah! That has always been the unexplained mystery. Once we have a simple, replicating form of life on the planet we can see it might thrive, spread and grow in complexity.
There are various proposals. Perhaps it arrived in an asteroid kicked off Mars or somewhere else. But that does no more than move the origin to a different place in the Solar System. Maybe it all began at mid-ocean ridges where hot mineral-laden springs flow from hot rock layers below the surface. Perhaps, yes.
We know that many of the precursors for life exist out among the stars. Here in the Solar System, comets and asteroids are often richly endowed with amino acids, ribonucleotides, and all sorts of smaller precursors. These are the building blocks of proteins, RNA, DNA and so forth. We understand how these precursors can form spontaneously given simpler materials like water, methane, ammonia, compounds including atoms of phosphorus, sulphur and so forth. It just takes chance interactions, time, and a source of energy like ultraviolet light. The basic ingredients are there in the gas clouds that condense to form new stars and the material orbiting in disks around them.
All of these things are fairly well understood, but there’s a gap in our understanding between the presence of the components and the presence of life. The gap has been closing little by little from both the astronomical and biological sides. But though it’s narrower now than ever before, it’s still a gap.
Life in a computer?
Well, yes! And, no.
Some clever work by Blaise Agüera y Arcas, a Google vice-president of engineering, has uncovered an intriguing process. Setting a very simple ‘machine’ running random code (no meaningful program whatsoever) and waiting for something to happen, shows that eventually some very simple self-replicating code will appear in the system, and once it exists it replicates very quickly and then slowly increases in complexity. It’s not biological life of course, but it has all the qualities that we would recognise as lifelike. It replicates itself, different forms of replicating code compete with one another, they evolve, and they grow more and more complex. This doesn’t show us in any detail how biological forms got started, but it demonstrates that self-replication could happen in principle, and given enough time that it’s almost inevitable.
For the detail and background you should listen to Sean Carroll interviewing Blaise, the conversation is absolutely fascinating.
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Many satellites are launched every year for profit-making purposes … TV broadcasting, imaging, weather forecasting, and internet provision.
Some time ago I was asked, ‘Why explore space?’
It’s a good question; space exploration is very expensive, surely we could spend the money on better and more important things? Surprisingly, perhaps, spaceflight has become a very profitable industry. Although exploration per se remains almost entirely government funded, exploration in past decades has sparked the profitable space industries that exist today.
Taking the world as a whole, we spend a very large amount of money on space exploration, US$117 billion in 2023. It’s fair to say that the USA almost certainly spends more than any other nation, and China and India both have major space programs, so does Europe (taken as a whole) through the joint ESA programmes (ESA is not part of the EU, however). Russia and Japan are major players too. You can view the figures as a bar chart from Statista.
It’s not quite as simple as it sounds, though. For one thing, material and human resources are much more expensive in some countries than in others, so US$1 billion buys a lot less in the USA or Europe or Australia than it does in China, or India, or Brazil.
Another thing to consider is that space research, spaceflight, and space exploration are not all about spending a lot of money, they are also activities that can generate a great deal of income. Economics is complex and difficult.
I think it may help us if we briefly review the history of space exploration.
The history of spaceflight
We have to go back to ancient and medieval times to find the first hints that people wanted to travel beyond the Earth. Even thousands of years ago, some people thought about leaving Earth behind. The Bible describes Elijah being taken up in a fiery chariot. The Koran describes Mohammed on a winged horse. The Greek, Icarus, wanted to fly high above the Earth. Dante’s ‘Divine Comedy’ in 1320 describes a journey to the heavens. ‘Kepler’s Dream’ in 1608 describes how Earth would look from the Moon. In 1657 Cyrano de Bergerac described a journey from Earth to the Moon.
Of course, much of this was fanciful in various ways, but people were thinking about it. Science fiction became popular in the 19th and, especially, the 20th century and some of the ideas discussed seemed quite plausible. Engineering experiments with solid and liquid fuelled rockets began in the early 20th century, and that’s when some people began risking money (and sometimes their lives) to make progress with early rockets. Costs were involved, but no income was generated.
By 1944 the wartime German government could see the tide had turned against them, with losses on the Russian front and in North Africa. Italy had fallen to the Allies and by the middle of the year southern and northern France had been invaded and German forces were struggling to hold on. Germany had been developing new weapons for some time, and now they began to use them in a final attempt to reverse impending defeat. Jet aircraft, the first cruise missile (the V-1) and the first rocket capable of reaching space (the V-2, the first ballistic missile) all came into play at this late stage of the war. Firing the V-2 vertically in a test, Nazi Germany became the first nation to reach space at 174.6 kilometres (108.5 miles) on 20 June 1944. The rocket entered space vertically and fell straight back as it didn’t have sufficient fuel to attempt the horizontal velocity necessary to go into orbit.
After Germany’s defeat in May 1945 there was a scramble by the USA, the Soviet Union, and to a lesser degree by the UK to capture unflown V-2s, plans and information, construction and test facilities, as well as the engineers and technicians behind the technology.
Rocket technology was developed further, both for use as a weapon and also for scientific research and space exploration. This has led to many nations engaging in spaceflight and space exploration in the late 20th and early 21st centuries.
Recent developments
So now we have set the scene. Space exploration has become technically possible. It remains difficult and expensive, though the development of advanced and miniaturised electronics and computers for control, and improved fuels, materials, and designs have reduced the costs and look set to reduce them even more substantially in future. One major change in the last decade is that we now have the first reusable rocket boosters. SpaceX is already flying some of its Falcon 9 boosters more than twenty times. The costs savings are enormous and other rocket companies are trying to catch up.
Given all of this, why would we want to explore space?
Reasons for exploring space
First, it’s worth mentioning that the reasons for exploring space are the same as those for exploring more generally. People are born explorers: the youngest infant begins exploring the environment as soon as they can crawl. There are only two requirements – an ability to move from one place to another, and a desire to find out what lies further away.
Given the ability we now have to reach ever further into space, we just naturally want to investigate what is there and understand it to the best of our ability. These days, automatic systems can travel to dangerous and hard to reach places and return images and measurements without the presence of human travellers. So we have good images and many kinds of measurement from every large body in the Solar System, and growing numbers of the smaller asteroids and comets. But automated systems have limitations in terms of decision making and judgement, limitations that require the presence of people. These limitations are more severe than first appears given the great distances involved in exploring space. When a rover on the Moon takes an image, we may be able to view it within a few seconds and send instructions on what to do next. On Mars it might take twenty minutes to receive the image and another 20 minutes for the instruction to reach the rover. So a Mars rover needs to navigate and make decisions on avoiding obstacles semi-autonomously.
So far we have travelled only to Earth orbit and to the Moon, but the urge to go further remains. We’re a nosy and inquisitive race; we want to know more, we want to find out, we love to solve mysteries.
The benefits so far
This is unlikely to be an exhaustive list, there are many benefits already and new ones keep moving from theory to practice. I’ll list those I can think of below.
Photographing the Earth’s surface from orbit. This benefits mapping, weather forecasting, resource discovery, agriculture, military intelligence and much, much more.
Understanding geology by comparing Earth rocks and minerals with those on the Moon, other planets, rocky moons, and so on. We are learning how Earth and the other planets formed, and how long ago.
Astronomy has advanced as telescopes are operated from space. Earth’s atmosphere causes reduced image clarity and blocks many wavelengths of light, X-rays, and other forms of radiant energy. Light pollution from cities is also avoided by putting a telescope into orbit. It also becomes far easier to identify smaller objects that might collide with Earth and potentially cause serious damage and loss of life.
Probes have travelled to distant solar system objects to return images and sometimes samples of surface material.
Manufacturing in micro-gravity can produce medical, engineering and scientific materials that simply cannot be made on Earth. Ultra pure proteins have aided medical science enormously in some areas, helping scientists understand protein structures for example, or manufacturing life-saving antibodies and drugs.
Understanding the inhospitable conditions of space itself and the other planets in our solar system provides a perspective that helps us value what we have here on Earth.
Communications systems have benefitted enormously from spaceflight. From TV satellites providing hundreds of high-resolution channels, to satellite internet availability for ships, aircraft and remote regions, the exploration of space has provided the technology behind these improvements. Good internet access for remote areas improves disaster rescue, allowing much quicker responses.
Satellite navigation has transformed many aspects of land, air and sea travel. Who wants to manage without their satnav while driving?
Spin-off technologies like solar panels, stronger materials such as carbon fibre, recycling and purification of air and water were all developed first because of space exploration and are now proving invaluable here on the ground as well.
New resources are becoming available as a result of space exploration. Rare and expensive metals from asteroids, ices from comets and the moons of planets in the outer Solar System are likely to become useful in the near- to mid-term future. This is not yet commercially viable, but will become so as space transport systems develop further.
I hope that brief round up will help my readers understand some of the why-questions around space exploration. In the early days it was an expensive operation, funded by governments, and often justified by military considerations. Today, much space activity is done by companies with a profit motive. Launch services are now largely commercial in nature, so too is the transport of people and materials to and from Earth orbit and even now to and from the Moon. And finally, many satellites are launched every year for profit-making purposes as well – TV broadcasting, imaging, weather forecasting, and internet provision to name just a few.
What’s in an image? Sometimes quite a lot, more than meets the eye.
I’m posting an image every day (or as often as I can). A photo, an image from the internet, a diagram or a map. Whatever takes my fancy.
Aloe aristata
Today’s picture is a close up of an Aloe aristata plant with a developing flower bud. All plants, animals, fungi, bacteria and even viruses have ways of reproducing themselves. That’s one of the defining characters of life of any kind. We can be absolutely confident that the same will be true of any life forms anywhere in the universe.
The Aloe flower bud will develop on a tall stalk and if the flowers that form are pollinated they will produce and release seeds that stand a chance of germinating and growing into new, similar, Aloe plants. In the natural way of things, each Aloe will produce an average of one new plant, and the population will remain in balance.
The only choices available to life are to survive for ever with no reproduction, or to live for a limited time and leave behind new versions to carry on the process. What life cannot do is live forever and reproduce: that would lead to overpopulation and catastrophic failure of resources. Even with reduced family sizes, the planet is no longer capable of supporting the billions of people on our planet. We face catastrophic population collapse due to lack of resources at some point unless we can reduce our population size in some other way first. That’s a matter of simple arithmetic, not a political statement or some kind of guesswork. If we don’t face and fix the issue, something else will sooner or later.
Themed image collections
The links below will take you to the first post in each collection
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What’s in an image? Sometimes quite a lot, more than meets the eye.
I’m posting an image every day (or as often as I can). A photo, an image from the internet, a diagram or a map. Whatever takes my fancy.
The fresh green of spring
There are few things as amazing as life. Perhaps there’s literally nothing as amazing as life in the entire universe! The photo shows the young, expanding leaves of a small-leaved lime tree (Tilia cordata).
Like all deciduous, temperate trees, leaf buds are formed the previous summer and over-winter after the old, mature leaves fall in late autumn. As temperatures increase in springtime, these buds swell and grow and the young leaves appear and expand. At first they’re a beautiful, pale green (lime green) but become a darker and duller shade as the days lengthen and they mature.
These processes all take place naturally in ways that are more complex than most of us might expect. Both plants and animal bodies are composed of countless tiny cells in much the same way that a large building might be made of bricks. Each cell is alive, contains a full copy of the organism’s DNA, and many of them have specialised roles to play. By cooperation and coordination they manage all the behaviours and activities that we see on the larger scale. So in some respects an expanding leaf is a lot like a growing community of people working together as a village or business. Having specialists makes it possible to do so much more, but cooperation becomes essential, not merely optional.
The rioting we’ve seen in some British cities in recent days has been disruptive and damaging to society as a whole. When the cells of an organism behave in uncoordinated and uncontrolled ways we call it a cancer. Rioting is a kind of cancer in a human society. We all know what happens when cancer becomes so widespread that the organism can no longer function. But organisms have ways of dealing with errant cells before they become overwhelming, and so do societies. Both police action and peaceful counter-demonstrations have been effective in controlling the UK riots in recent days.
Themed image collections
The links below will take you to the first post in each collection
If you enjoyed this or found it useful, please like, comment, and share below. Send a link to friends who might enjoy the article or benefit from it – Thanks! My material is free to reuse (see conditions), but a coffee is always welcome and encourages me to write more often!
What’s in an image? Sometimes quite a lot, more than meets the eye.
I’m posting an image every day (or as often as I can). A photo, an image from the internet, a diagram or a map. Whatever takes my fancy.
It’s quite amazing how life clings on, even in the most adverse circumstances. This plant was growing in my front drive, somehow finding a way to get its roots into a narrow gap in the block paving. The blocks were designed by a garden landscaping company and manufactured to particular standards of hardness and resistance to my car rolling over them. They were designed to last.
The plant, on the other hand, is a living organism. Nobody designed or manufactured it – life is much more wonderful than that! The universe we live in is tailored to build ever more complex things from very simple beginnings. A handful of quantum fields is all it takes, and these are exquisitely able to give rise to fundamental subatomic particles. These group together, eventually settling into simple atomic nuclei. As the universe expanded and cooled, atoms of simple elements appeared, almost entirely hydrogen and helium. Stars condensed and formed heavier elements up to iron. I could go on, but it’s a long story! Maybe some other time?
For now, just consider the battle between order (my paving blocks and the urge I have to remove weeds that neither I nor my wife want to see growing there) and disorder (weeds thriving wherever they can, despite my best efforts). Life always wins in the end, it seems!
Themed image collections
The links below will take you to the first post in each collection
If you enjoyed this or found it useful, please like, comment, and share below. Send a link to friends who might enjoy the article or benefit from it – Thanks! My material is free to reuse (see conditions), but a coffee is always welcome and encourages me to write more often!
What’s in an image? Sometimes quite a lot, more than meets the eye.
I’m posting an image every day (or as often as I can). A photo, an image from the internet, a diagram or a map. Whatever takes my fancy.
We have something a little different today. This has been nicknamed ‘The Penguin and Egg’ by some astronomers, I think it looks rather more like a hummingbird. But its real name is not so memorable, the penguin is NGC2936 and the egg is NGC2937. They are a pair of colliding galaxies and will eventually merge. This view comes courtesy of the James Webb Space Telescope; the website is worth a visit, there are many more images like this one.
The universe we inhabit is huge. Those two galaxies are interacting, but it takes light 100 000 years to travel between them. Click the image and look closely and you’ll see dozens more galaxies in the far distance beyond this pair. We are surrounded by awesomeness!
Themed image collections
The links below will take you to the first post in each collection
If you enjoyed this or found it useful, please like, comment, and share below. Send a link to friends who might enjoy the article or benefit from it – Thanks! My material is free to reuse (see conditions), but a coffee is always welcome and encourages me to write more often!
Here’s a nice NASA video illustrating the dark … side of the Moon.
What do people mean when they talk about ‘the dark side of the Moon’? Is there a dark side of the Moon at all? How did this strange phrase originate?
This popular phrase is usually misunderstood. Astronomers often object strongly, ‘The far side of the Moon gets the same amount of sunlight as the visible near side’. They are both correct and incorrect. In terms of solar illumination they’re correct, of course.
But good astronomers are not necessarily good linguists. The word ‘dark’ in this phrase does not mean absence of light, it means hidden from view or obscured. Dark meant ‘hidden’ or ‘secret’ long before it came to be used to mean an absence of light. See the Wiktionary definition.
Here’s a nice NASA video illustrating the dark (hidden) side of the Moon. You’ll notice it has night and day periods of course, just like the near side.
Here’s a simple diagram of a hydrogen atom. The little black ball is the nucleus, a proton, 10 000 times smaller than the atom as a whole, the white part represents an electron, spread out like a cloud around the nucleus. The proton and the electron were once thought of as fundamental particles that had no underlying structure. For the electron that remains true. The proton on the other hand consists of three quarks, but for the purposes of chemistry we can still think of it as ‘fundamental’.
A hydrogen atom can react with other atoms in quite specific ways. New and more complex behaviour emerges as atoms combine. Here are some of those emergent properties:
A molecule of methane, four hydrogens attached to a carbon atom
Two atoms of hydrogen can combine as a molecule of hydrogen, a gas that can become explosive when mixed with air.
Two hydrogen atoms and an oxygen atom can combine as a water molecule. Everyone knows that pure water is safe to drink.
Four hydrogens and a carbon atom can combine as a molecule of methane gas. This is the domestic gas that we use for cooking and for heating our homes. Methane is also a powerful greenhouse gas, contributing to global heating.
Three hydrogens and a nitrogen atom can combine as a molecule of ammonia, a poisonous gas that dissolves readily in water.
Two hydrogens and a suphur atom can combine as a molecule of hydrogen suphide, a gas that smells like rotten eggs.
There are many other molecules that include hydrogen.
Protons, and similar particles called neutrons can combine in larger numbers to make heavier and larger nuclei surrounded by much larger clouds of electrons (we’re leaving out a great deal of detail here). Together, these are the various chemical elements; there are more than 100 different kinds. Sodium, oxygen, phosphorus, chlorine, nitrogen, lead, iron, gold, sulphur, copper, tin and so on.
Chemistry
So – Take 100 different atoms and combine them together in various ways and you can clearly see that many, many different molecules are possible. Imagine 100 different kinds of Lego bricks and you begin to see the range of possibilities. There are rules of chemistry that restrict the combinations that can form, but even allowing for those rules, the number of possible molecules is huge . Here are some examples.
Sulphuric acid – two hydrogens, a sulphur, and four oxygen atoms
Table salt – one sodium and one chlorine atom
Bleach – two chlorine atoms
Laughing gas – two nitrogens and two oxygen atoms
We see chemistry appearing as soon as we have atoms. Chemistry just isn’t there in the world of subatomic particles like protons, neutrons and electrons. Like every object you can think of, we are made of atoms in complex chemical combinations so it’s quite hard for us to imagine a universe without chemistry. And atoms began emerging very early in the formation of the universe, perhaps 18 000 years after the origin. Chemistry started around 370 000 years as the universe continued to cool and atoms were able to begin combining ever more freely. At first hydrogen, helium and a small amount of lithium were the only elements available, all the others up to iron formed inside stars, while exploding stars (supernovae) generated the heavier elements and scattered these and the lighter elements far and wide. Once that had happened, perhaps 500 million years ago, the full range of atoms were available and chemistry took off in earnest.
Atoms are emergent, beginning to form once the universe became cool enough. And chemistry emerges given the presence of atoms and even lower temperatures. Could atoms and chemistry have been predicted given the presence and behaviour of subatomic particles? Perhaps. But it would have taken a real genius, a physicist with great foresight and imagination. But physicists are made of atoms and complex chemistry – so the real answer must be ‘no’!
That’s the thing about emergence – new kinds of objects and new processes ’emerge’ when the materials and conditions to do so exist. Sometimes emergence is rapid, even sudden. But as we shall see in a future post, sometimes it’s very slow indeed, or long delayed even after the possibility of emergence has existed for a very long time. Chemistry emerged quickly once atoms and low enough temperatures became available. So the opportunity was ‘slow’ to occur, but the emergence was immediate thereafter. We can think of these things separately – emergence opportunity, emergence delay, and emergence rate.
Theorists can move forward again – and the picture seems a little more complicated than we thought.
Where did we come from, and how? We’ve long thought in terms of an evolutionary ‘tree’, but our origins in Africa are more like a braided channel. This idea provides a better fit to the data.
Based on fossil evidence alone, studies of human evolution have long agreed that modern humans evolved in east Africa and radiated out from there. But with the development of cheap, fast and reliable DNA evidence from modern populations, and DNA from fossil teeth and bone samples, it’s becoming clear that theorists can move forward again – and the picture seems a little more complicated than we thought.
Human dispersion, events described in the article all took place in Africa – Image from Wikimedia
On 17th May, Ragsdale and others published a research paper in Nature; ‘A weakly structured stem for human origins in Africa’; their evidence suggests evolutionary connections in populations that were separated for a while before recombining. So instead of an evolutionary tree (which most people were expecting) it seems that our human past is more like a set of braided channels.
Previous views on human evolution proposed a tree structure (branching but not recombining). However, the new ‘weakly structured stem’ model fits the data better than a tree model. It also explains the diversity of genetic forms in modern human populations, and shows that there is no single place in Africa where humans ‘originated’. After this process within Africa, humans spread out as show in the map.
Journeys of Heart and Mind 
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