The Moon is not always a friend of terrestrial astronomers. The light it casts, especially during its full phase, deprives the night sky of the darkness needed to observe other celestial bodies. This must be frustrating. Along with those clouds that sometimes completely block our views of the heavens. And don’t get anyone started on the Sun.
Astronomers use the Roche Limit to calculate how close an object – like a moon – can orbit another object – like a planet. This is the point where the difference between the tidal forces on the “front” and “backside” are large enough that the object is torn apart, and if this sounds familiar you might want to look up “spaghettification.” This is all based on the radius of the planet and the density of the planet and moon. If the moon got close enough to the Earth, around 18,000 km, it would pull apart and be shredded into a beautiful ring. And then the objects in the ring would enter the Earth’s atmosphere and rain down beautiful destruction for thousands of years.
First, there is cosmic radiation from the Sun and the rest of the stars in our galaxy and beyond. How much we get depends on the altitude at which we live and on fluctuations in the Earth’s magnetic field. And then there’s radiation from the Earth itself, including radon. Here, too, geography is a factor: in some places radon can be found leaking into the atmosphere in significantly larger amounts. Naturally radioactive solids such as uranium and thorium in rock and soil also make their contribution. The global average annual radiation dose is 2.4 mSv. To put this in perspective, that’s about the same as 120 chest X-rays.
We are used to thinking of ourselves as composed of billions of cells, but Falkowski points out that we also consist of trillions of electrochemical machines that somehow coordinate their intricate activities in ways that allow our bodies and minds to function with the required reliability and precision. As we contemplate the evolution and maintenance of this complexity, wonder grows to near incredulity.
I hope you’re not eating right now, but as we all know, there is more bacteria lurking on computer keyboards, and smartphones, than there is the average toilet seat. Delightful.
However, there appears to be a fair few microbes on the hand of a child who has been playing outside for an hour or two, as Tasha Sturm, Californian lab technician, discovered recently. This photo is the result of a handprint her eight year son made on a petri dish, after being left to incubate for a few days.
I know that our immune system can sometimes mount a resistance to certain diseases we’ve had before, such as measles, but I didn’t realise that a record, as it were, of these disorders is stored in every drop of our blood.
You’ll probably remember the last time you had the flu, but what about that time you had measles – or was it chicken pox? Your blood knows: it keeps a record of every virus you’ve ever been infected with. A tiny drop of the stuff can now be tested to reveal a person’s viral history.
For decades, paleontologists’ only fossil link between birds and dinosaurs was archaeopteryx, a hybrid creature with feathered wings but with the teeth and long bony tail of a dinosaur. These animals appeared to have acquired their birdlike features – feathers, wings and flight – in just 10 million years, a mere flash in evolutionary time. “Archaeopteryx seemed to emerge fully fledged with the characteristics of modern birds,” said Michael Benton, a paleontologist at the University of Bristol in England.
In twenty trillion years, give or take, once the final generation of stars, possibly red dwarfs, have expended the last of their energy, and shine no more, the universe will become a dark, freezing, entity. So will intelligent life, of some, maybe transhuman sort, continue to exist?
As the universe continued to cool, our AI descendants would need to take action. Unlike Asimov, Dyson does not suggest a mechanism for reversing the growth of entropy. Rather, he imagines a gradual slowing down of thinking processes. Only necessary thoughts would transpire and these would happen at an increasingly snail-like pace. Between thoughts, the AI devices would hibernate to conserve vital, usable energy. By spacing out thoughts more and more, Dyson argues, intelligent existence could persist almost indefinitely, although the number of total thoughts would still be finite.
That’s good to know. In the meantime though, let’s turn our attention to other current, and more pressing, matters.
I didn’t know that there was a branch of mathematics dedicated to the study of queuing, but there you have it. And if you so desire, you can read a little more about what is sometimes referred to as queuing theory.
To cut to the chase though, if confronted with a number of longer lines, which might be the best one to queue in? It’s possible that it may be the one to the left of the others. Understand however that your mileage may vary:
When faced with two choices – a line to the left or a line to the right, some people believe that the left-hand route will be faster. That’s because approximately 90% of the population is right-handed, and so they tend to naturally head to the right. This may be an old wives’ tale, but if you’re at a theme park with long lines, heading left is worth a try.
A bicycle that moves left when when you turn the handle bars to the right. That’s certainly not your usual, run-of-the-mill, pedal powered device. So how much difficulty might you have riding a bike that operates thus?
It looks like it might pose quite the challenge, given riding a conventional bicycle is far more demanding than we realise, in fact our brain is required to formulate an algorithm to deal with the task…
The algorithm associated with riding a bike in a person’s brain is extremely complicated. Downwards force on the pedal, leaning your whole body, pulling and pushing the handle-bar, gyroscopic procession in the wheels; every single force is a part of this algorithm. And if you change any one part, it affects the entire control system.