We know the internal anatomy of the Earth reasonably well thanks for over a century of geological studies, including the details revealed by the propagation of seismic waves; this was the one of the groundbreaking (literally!) discoveries of Croatian polymath Andrija Mohorovičić; I've been privileged to have seen in Zagreb his original notebooks with his calculations to about 5 decimal places in which he traced the latencies and propagation times for Earthquakes; this showed him that the Earth is a bit like an onion inside with different layers at different depths.
But today someone called our Ask! the Naked Scientists radio show and enquired whether other planets have a similar interior, and what we do and do not know.
I was able to point out that we know that Mars, for instance, is volcanic (or at least was); we also know that Venus is probably resurfacing itself regularly.
But presumably we know much less about the internal structure of the other bodies in the solar system, save for what we can infer from similarities or differences with the Earth, magnetic measurements and gravity measurements...?
I'm putting together a piece to make viruses and the spread of infection more comprehensible for non-specialists. In explaining why the particles spread through the air and remain airborne for so long I would like to use an analogy like "these viruses are smaller than some of the particles of smoke that come off the end of a cigarette / exhaust pipe".
I thought I'd better fact check this first!
A flu virus is about 100nm (1/10,000th mm); but how big is an average smoke particle?
I chanced upon this live version of this favourite song of mine; it's phenomenal; how these guys got this so perfect live is a feat in itself. My only regret is that I was too young to have seen this when it was in its heyday...
I decided to educate myself more about particle physics earlier this year and in doing so turn some random names into some actual knowledge and understanding.
I was surprised to learn that the matter in the University is formed entirely from down and up quarks and electrons. This means you can make protons, neutrons and atoms - and therefore everything that we can "see" - from just these species.
What I am struggling to comprehend, then, is what the other 4 species of quark (strange and charm, bottom and top) actually "do".
As far as I can make out from reading the literature, these are analogous in almost every way to a down and up quark but differ only in mass with the charm and top quarks being the more massive in ascending order and the strange and bottom quarks showing a similar pattern.
So, why do these other particles exist and what is/are their role(s).
Also, could we make a "heavy" proton from a couple of top quarks and a bottom quark?
I was speaking with a light person over lunch the other day and we got to talking about photon momentum (which he works on), the YORP (Yarkovsky–O'Keefe–Radzievskii–Paddack) Effect and, off the back of that, Crooke's radiometer.
We were debating the workings of the radiometer and my friend said he thought the radiometer would behave differently in an ultrahigh vacuum compared with the "standard" vacuum traditionally used. He went as far as to suggest that it should rotate the other way.
On this week's Ask! The Naked Scientists podcast someone enquired about the means by which rockets can be steered or guided as they ascend; his observation was that the craft goes straight up for a while then appears to flatten off.
He was wondering why and how this is achieved.
I thought this was an interesting point for discussion...
A lady called up the Ask! The Naked Scientists radio show on Talk Radio 702, South Africa, today to ask about an experiment she'd seen regarding a spinning sphere at 600 million RPM (or "500,000 times faster than a washing machine", as one source observed, presumably feeling they needed to provide a link to something familiar so readers could identify with the story!). This sphere, the woman said, "disappeared" at high speed. I asked her for the reference, which she sent to me.
The study is quite interesting; the group in question were "spinning" a particle using laser pulses to apply a torque.