About ianmillerblog

I am a semi-retired professional scientist who has taken up writing futuristic thrillers, which are being published by myself as ebooks on Amazon and Smashwords, and a number of other sites. The intention is to publish a sequence, each of which is stand-alone, but when taken together there is a further story through combining the backgrounds. This blog will be largely about my views on science in fiction, and about the future, including what we should be doing about it, but in my opinion, are not. In the science area, I have been working on products from marine algae, and on biofuels. I also have an interest in scientific theory, which is usually alternative to what others think. This work is also being published as ebooks under the series "Elements of Theory".

Planets Being Formed Now

An intriguing observation, recorded in Nature Astronomy3, 749 (2019) is that two planets are being formed around the star PDS 70, a star about 370 light years from Earth in the constellation of Centaurus. The star is roughly 76% the mass of the sun. Its temperature is 3972 degrees K, so it is a bit cooler than our sun, and is about 1.26 time bigger. What that means is it has yet to collapse properly. Because at least some of the accretion disk is still there, gas is still falling towards the star, and towards any planets that are still forming. Because giants have to form quickly, the huge amount of gas falling into them gets very hot, the planets glow, and if they are far enough away from the star, we can see them through very large telescopes. The first such planet to be observed in this system (Labelled PDS 70 b) is about 7 times as big as Jupiter, and is about 23 AU away from the star, i.e. it is a little further away from its star as Uranus is from our star. (1 AU is the Earth-sun distance.)

We can detect the gas flowing into the planet by the spectral signal Hα at 656.28 nm, and by selecting such a signal much of the general light is filtered out and gas can be seen streaming into planetary objects. The planet PDS 70 b was confirmed in the cited reference, but there is an addition: PDS 70 c, which is about 38 AU from its star, also with about 4 AU uncertainty. This is a bit further away from its star as Neptune is from ours, which suggests an overall system that is a bit more expanded than ours.

These planets are interesting in terms of generating a theory on how planets form. The standard theory is that dust from the accretion disk somehow accretes to form bodies about the size of asteroids called planetesimals, and through gravity these collide to form larger bodies, which in turn through their stronger gravity collide to form what are called embryos or oligarchs, and these are about the size of Mars. These then collide to form Earth-sized planets, and in the outer regions collisions keep going until the cores get to about ten times the size of Earth, then these start accreting gas, until eventually they become giants. Getting rid of heat is a problem, and consequently newly formed giants are very hot and seem like mini-stars.

The problem with that theory is timing. The further away from the star, the dust density is much lower simply because there is more space for it and even if you can form planetesimals, and nobody has any idea how they formed, the space between them gets so big their weak gravity does not lead to useful collisions. There is a way out of this in what is called the Grand Tack model. What this postulates is that Uranus and Neptune both grew a little further out than Saturn, and as they grew to be giants their gravity attracted planetesimals from further out. However, now the model argues they did not accrete them, but instead effectively pulled them in and let them go further in towards the star. By giving them inwards momentum, they got “lift” and moved out. They kept going until Neptune ran out of planetesimals, which occurred at about 32 AU.

Now, momentum is mass times velocity, which means the bigger the planet that is moving, the more planetesimals it needs, although it gets a benefit of being able to throw the planetesimal faster through its stronger gravity. That effect is partly cancelled by the planetesimals being able to pass further away. Anyway, why does a star that is about ¾ the size of our star have more planetesimals that go out almost 20% further. In fairness, you might argue that is a rather weak conclusion because the distances are not that much different and you would not expect exact correspondence. Further, while the masses of the giants are so much bigger than ours, you might argue they travelled then accreted the gas.However, there is worse. Also very recently discovered by the same technique are two planets around the young star TYC 8998-760-1, which is about the same size as the sun. The inner planet has a mass of 14 times that of Jupiter and is 162 AU from the star, and the outer planet has a mass of 6 times that of Jupiter and is 320 AU from the star. It is difficult to believe that one star of the same size as another would inadvertently have a huge distribution of planetesimals scattered out over ten times further. Further, if it did, the star’s metallicity would have to be very much higher. Unfortunately, that has yet to be measured for this star. In my opinion, this strongly suggests that this Grand Tack model is wrong, but that leaves open the question, what is right? My usual answer would be what is outlined in my ebook “Planetary Formation and Biogenesis”, although the outer planet of TYC 8998-760-1 may be a problem. However, that explanation will have to wait for a further post but those interested can make up their minds from the ebook.

Betelguese Fades

Many people will have heard about this: recently Betelgeuse became surprisingly dim. Why would that be? First, we need to understand how a star lives. They start by burning hydrogen and making helium. This is a relatively slow process, the reason being that enormous pressures are required. The reason for this is that hydrogen nuclei repel each other very strongly when they get close, and the first step seems to be to make a helium atom with no neutrons, which is two protons bound. However, they are not bound very tightly, and the electric force between them makes them fly apart in an extremely short time. Somewhere within this time, the pressure/temperature has to force an electron into one of the nuclei to transform it into a neutron, when we have deuterium, which is stable. The deuterium goes on to make the rather stable helium nuclei, and liberate a lot of energy per reaction. However, the probability of such reactions is surprisingly low, mainly because of the difficulty in making 2He. The rate is increased by temperature and pressure, but the energy liberated pushes the rest of the matter away, so an equilibrium is formed. The reason the sun pours out so much energy is because the sun is so big. The bigger the star, the more the central pressure, and the faster it can burn its hydrogen, so paradoxically the bigger the star the sooner it runs out of fuel.

Betelgeuse is the tenth brightest star in the night sky, and after Rigel, the second brightest in the constellation of Orion. It has a mass somewhere between 10 – 20 times that of the sun, so at its centre the pressure due to gravitation will be far greater than our sun, hydrogen would have burned much faster, and accordingly, it has run out of hydrogen fuel so much more quickly. When it does, if it is big enough, its core collapses somewhat due to the loss of repulsive energy until it gets hot enough to burn helium, which releases so much more energy that the outer part of the star bloats. If placed in the centre of the solar system, the surface of Betelgeuse would come close to the orbit of Jupiter. All the rocky bodies would be gone. As it grows to that size, it is not really in equilibrium. If it bloats too far, the pressure drops, the outer surface collapses, the pressure increases, reactions go faster, it expands, and so on. The periods of such pulsations can be up to thousands of days. When they pulsate, we see that as a fluctuation in brightness. It will keep pulsating and behaving errtatically until sometime, most probably within the next 100,000 years, it will collapse and form a supernova. As a star like Betelgeuse pulsates, it brightens and dims. All very expected, but recently it has dimmed to about 40% of what it was before. Was this the prelude to a supernova? The short answer is, we don’t know, but the pulsations got our attention.

Because of the size, the gravity is weaker on the surface, and huge bursts of energy send gas as a burst out into nearby space. While we have our solar winds and coronal mass ejections, those of a red supergiant are somewhat more massive, and they send out massive clouds of gas and dust. One of the first “guesses” as to the cause of the dimming was the blocking of light by dust, but further studies showed that that cannot be the case because the spectral data was more consistent with a significant mean surface cooling. Further, Betelgeuse is close enough that major telescopes can resolve the star as a ball, and it was found that between 50 – 70% of the star’s surface was significantly cooler than the rest. The star appears to have a massive star spot! So, for the time being it seems likely that Betelguese will last a little longer. As an aside, do not feel sorry for life on a planet aorund it. Betelguese is only about 20 million years old. There is no time for life to develop around such massive stars.

Ebook Discount

Until the end of July, Troubles will be discounted to $0.99 or £0.99, and with similar discounts across all Amazon stores. It is also discounted in Smashwords for those who wish to purchase .epub.  Troubles is a dystopian novel, in which thanks to the invention of fusion power the world is starting to emerge from a near total economic meltdown, and in which vested interests have maintained their preferred lifestyle and have provided just sufficient for the average citizen to exist and not riot. Now the economy will grow again, and the growth will not be shared. The benefits will go to those with the money and/or those with the guns. Politicians emerge, there is the promise of democracy and sharing, but corruption ensures the innocent are to be fooled. It is not an easy ride for anyone. A dystopian tale of dishonour, revenge, greed, and the few who wish to restore morality and justice for all.


Masks and COVID-19

Unfortunately, most people seem to think that science is about “knowing stuff”. In my opinion, that is plain wrong. Science is about the methodology needed to find out about nature. Of course, once we find out we record our findings so others do not have to waste their time rediscovering, and it is this ability to “stand on the shoulders of others” that gets us to where we are. We can deduce things from what we know, but as Aristotle noted in his Prior Analytics, if we come across a problem for which there are no means to deduce, we have to induce the premises necessary to make progress. That means examining the observed data and making guesses. The better spread the data, the more likely the guesses will be good, but the nature of induction is that it can be wrong. That is the basis of Popper’s concern that the aim should be falsifiability, to get rid of what is wrong. In happen to agree that is a good objective, but it is not the only one, if for no other reason than if we do not induce new hypotheses, eventually there is nothing to falsify, but equally we may remain quite ignorant of certain aspects of nature.

So, how does this apply to COVID-19? When we started this, we knew very little, although in a very short time we had found the structure of this virus. Also, while it was a new virus, we do know quite a bit about viruses in general. If you look around the web, we see that there have been a huge number of hypotheses, usually asserted as fact. In New Zealand the hypothesis applied was, if you stop transmission for two transmissibility cycles, the virus, unable to reproduce, will be eliminated. Interestingly, some assert that isn’t science – it is brute force, nevertheless it follows logic and better still, it worked. 

Some asserted that we should aim for herd immunity. The estimated number of cases needed to get this vary, but let us put this at the dead minimum of 60%. I believe that is too few because the SARS virus is transmitted for an unusally long time from a patient, nevertheless the planetary population is, say, 7.7 billion. That gives us 4.62 billion cases minimum. The death rate seems to be about 5% across a broad population age group, so that gives 231 million  deaths as the minimum price to pay for herd immunity. If you don’t like the 5%, put in your own figure. Places with few cases and good medical care lower that, but to get herd immunity you need that 4.6 billion cases and do we have that many good hospitals? Sweden is sometimes cited as an ideal example. However, they have had 74,333 cases and 5550 deaths at the time of writing this from a population of a little over 10 million. The death rate is 7.47% and the infection total is about 0.44% of the population, which is a long way from herd immunity. Maybe the Swedes are very careful, but the virus is still reproducing and such care eventually fails for each person. 

If you check the web now, you will see all sorts of assertions, and some people seem to make up figures. The figures I use are those posted by authorities as confirmed cases. It is true there will be many more cases where the virus did not create symptoms, especially in the young, but unfortunately, these are merely incubators for the virus. Spain has had 300,136 case and 28,401 deaths, a death rate of alost 9.5%, so are there a huge number of unrecordered cases? Spain has a population of about 46.75 million, so the confirmed cases reflect about 0.65% of the population, however a random sample of 61,000 Spaniards were given blood tests and apparently 5% of them had antibodies. It is still unclear from that report what the antibodies are to, because they may be to coronaviruses as a group, and who has not had a cold?

As for more misinformation, originally the WHO stated there was no reason to wear masks, but now they are saying yes, masks are good. Then we see that masks are good because the virus is spread in droplets, hence the two meter distancing. Then we see statements that the virus is small and will be lurking as an aerosol, hence the masks won’t offer protection. What do you make of that? 

In my opinion, the scientific response is obvious. First measure the air around such patients and see if the virus is airborne. There are various ways this could be done. The second is to measure the efficiency of masks by pumping air exhaled from patients that are known to have the virus (by testing) through the masks and see if the virus is removed. If we did that, we would know whether masks worked, and more to the point we would know whether certain masks were better than others.The logic of masks is that they cannot do any harm, and they should stop some of the viruses. That seems logical, but surely we can do better.

Geoengineering: Shade the World

As you may have noticed when not concerned about a certain virus, global warming has not gone away. The virus did some good. I live on a hill and can look down on some roads, and during our lock-down the roads were strangely empty. Some people seemed to think we had found the answer to global warming, as much less petrol was bing burnt, but the fact is, even if nobody drove we were still producing net amounts of CO2 and other greenhouse gases, and even if we were not doing that, the amounts currently in the air are still out of equilibrium and would continue to melt ice and lead to high temperatures. In the northern hemisphere now you have a summer so maybe you notice.

So, what can we do? One proposal is to shade the Earth’s surface. The idea is that if you can reflect more incoming solar radiation back to space there is less energy on the surface and . . .  Yes, it is the ‘and’ wherein lies the difficulties. We get less radiation striking the surface, so we cool the surface, but then what? According to one paper recently published in Geophysical Research Letters (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL087348 ) the answer is not good news. They have produced simulations of models, and focus on what are called storm tracks, which are relatively narrow zones in oceans where storms such as tropical cyclones and mid-latitude cyclones travel through prevailing winds. Such geoengineering, according to the models, would weaken these storms. Exactly why this is bad eludes me. I would have thought lower energy storms would be good; why do we want hundreds of thousands of citizens have their properties leveled by hurricanes, typhoons, or simply tropical cyclones as they are known in the Southern Hemisphere? This weakening happens through a smaller pole to equator temperature difference because most of the light reflected is over the tropics. Storms are heat engines at work, and the greater the temperature difference, the more force can be generated. The second law of thermodynamics at work. Fine. We are cooling the surface, and while it may seem that we are ignoring the ice melting of the polar regions, we are not because most of the heat comes from ocean currents, and they are heated by the tropics.

More examples: we would reduce wind extremes in midlatitudes, possibly lead to less efficient ventilation of air pollution, may possibly decrease low cloud cover the storm‐track regions and weaken poleward energy transport. In short, a reasonable amount of that is what we want to do anyway. It is also claimed we would get increased heat waves. I find that suspicious, given that less heat is available. It is claimed that such activities would alter the climate. Yes, but that is what we would be trying to do, namely alter it from what it might have been. It is also claimed that the models show there could possibly  be regional reductions in rainfall. Perhaps, but that sort of thing is happening anyway. Australia had dreadful bushfires this year. I gather forest fires were going well in North America also.

One aspect of this type of study that bothers me is it is all based on models. The words like ‘may’, ‘could’ and ‘possibly’ turn up frequently. That, to me, indicates the modelers don’t actually have a lot of confidence in their models. The second thing that bothers me is they have not looked at nature. Consider the data from Travis et al.(2002) Nature 418, 601.  For the three days 11-14 Sept. 2001 the average diurnal temperature ranges averaged from 4000 weather stations across the US increased on average 1.1 degrees C above the average from 1971 – 2000, with the highest temperatures on the 14th. They were on average 1.8 degrees C greater than the average for the two adjacent three-day periods. The three days with the increase were, of course, the days when all US aircraft were grounded and there were no jet contrails. Notice that this is the difference between day and night; at night the contrails retain heat better, while in daytime they reflect sunlight.  Unfortunately, what was not stated in the paper was what the temperatures were. One argument is that models show while the contrails reflect more light during the day, they keep in more heat during the night. Instead of calculations, why not show the actual data?

The second piece of information is that the eruption of Mount Pinatubo sent aerosols into the atmosphere and for about a year the average global temperature dropped 1 degree C. Most of that ash was at low latitudes in the northern hemisphere. There are weather reports from this period so that should give clues as to what would happen if we tried this geoengineering. This overall cooling was real and the world economies did not come to an end. The data from that could contribute to addressing the unkn owns.

So, what is the answer? In my opinion, the only real answer is to try it out for a short period and see what happens. Once the outcomes are evaluated we can then decide what to do. The advantage of sending dust into the stratosphere is it does not stay there. If it does not turn out well, it will not be worse than what volcanoes do anyway. The disadvantage is to be effective we have to keep doing it. Maybe from various points of view it is a bad idea, but let us make up our minds from evaluating proper information and not rely on models that are no better than the assumptions used. Which choice we make should be based on data, not on emotion.

Scientific Discoveries, How to Make Them, and COVID 19

An interesting problem for a scientist is how to discover something? The mediocre, of course, never even try to solve this while it is probably only a small percentage that gets there. Basically, it is done by observing clues then using logic to interpret them. The method is called induction, and it can lead to erroneous conclusions. Aristotle worked put how to do it, and then dropped the ball at least twice in his two biggest blunders when he forgot to follow his own advice. (In fairness, he probably made his blunders before he worked put his methodology, and lost interest in correcting them. The Physica was one of his earliest works.) 

The clues come from nature, and picking them up relies on keeping eyes open and more importantly, the mind open. The first step is to seek patterns in what you observe, and try to correlate your observations. The key here is Aristotle’s comment that the whole is more than the sum of the parts. That looks like New Age nonsense, but look at it from the mathematics of set theory. A set is simply a collection of data, usually expressed as numbers, but not anything should go into it. As an example, I could list all green things I can see, but that would be pointless. I could list all plants, and now I am making progress into botany. The point is, the set comprises all the elements inside it, together with the rule that conveys set membership. It is the rule that we seek if we wish to make a discovery and in effect we have to guess it by examining the data. This process is called induction, and if we get some true statements, we can move on to deduction. 

There are, of course, problems. Thus we could say:

All plants have chlorophyll

Chlorophyll is green

Therefore all plants are green.

That is untrue. The chlorophyll will be green, but the plant may have additional dyes/pigments. An obvious case is red seaweed. The problem here is the lazy “therefore”. Usually it is somewhat more difficult, especially in medicine.

Which, naturally in these times, it brings me to COVID-19. What we find is very young people, especially girls, are more or less untroubled. The old have a lot more trouble, and, it turns out more so old men. Now part of the trouble will be that the old have weaker immune systems, and often other weaknesses in their bodies. Unlike wine, age does not improve the body. That is probably a confusing observation, because it leads nowhere and is somewhat obvious.

Anyway, we have a new observation: if we restrict ourselves to severe cases in hospitals, there is a serious excess of bald men. Now, a correlation is not causative, and trying to work out the cause can be fraught with difficulty. In this case, we can immediately dismiss the idea that hair has anything to do with it. However, baldness is also correlated with higher levels of androgens, which are male sex hormones. It was also found that the severe cases in males also usually had high levels of androgens. By itself, we can show this is not a cause either.

So, this leads to a deeper investigation, and it is found that the virus uses an enzyme called TMPRSS2 to cleave the Sars-Cov-2 spike protein, and this permits the cleaved spike to attack the ACE2 receptors on the patient’s cells, and thus permit the viral RNA to enter the cell and begin replicating. What the androgens do is to activate a gene in the virus that expresses TMPRSS2, so what the androgens do is to increase the amount of enzyme necessary to attack a cell. This suggests as a treatment something that will inhibit the viral gene so no TMPRSS2 is expressed. We await developments. (Suppressing androgens in men is not a good idea – they start to grow breasts. However, it also suggests that ACE inhibitors, used to reduce hypertension, might offer some assistance.) Now, the value of a theory can be shown by whether it helps explains something else. In this case, it argues that since pre-puberty children should be more resistant, and girls keep this benefit longer. That is found. It does not prove we are correct, but it is comforting. That is an example of induced science. Induction does not necessarily produce the truth, and conclusions can be wrong. We find out by pursuing the consequences, and either finding we have discovered something, or go back to the drawing board.

The Fermi Paradox: Where are the Aliens?

This question, as much as anything, illustrates why people have trouble thinking through problems when they cannot put their own self-importance to one side. Let us look at this problem not from our point of view.

The Fermi paradox is a statement that since there are so many stars, most of which probably have planets, and a reasonable number of them have life, more than half of those are likely to have been around longer than us and so should be more technically advanced, but we have seen no clue as to their presence. Why not? That question begs the obvious counter: why should we? First, while the number of planets is huge, most of them are in other galaxies, and of those in the Milky Way, stars are very well-separated. The nearest, Alpha Centauri, is a three star system: two rather close stars (A G-type star like our sun and a K1 star) and a more distant red dwarf, and these are 4.37 light years away. The two have distances that vary between 35.6 AU to 11.2 AU, i.e. on closest approach they come a little further apart than Saturn and the sun.  That close approach means that planets corresponding to our giants could not exist in stable orbits, and astronomers are fairly confident there are no giants closer to the star. Proxima Centauri has one planet in the habitable zone, but for those familiar with my ebook “Planetary Formation and Biogenesis” will know that in my opinion, the prospect for life originating there, or around most Red Dwarfs, is extremely low. So, could there be Earth-like planets around the two larger stars? Maybe, but our technology cannot find them. As it happens, if there were aliens there, they could not detect Earth with technology at our level either.  Since most stars are immensely further away, rocky planets are difficult to discover. We have found exoplanets, but they are generally giants, planets around M stars, or planets that inadvertently have their orbital planes aligned so we can see eclipses.

This is relevant, because if we are seeking a signal from another civilization, as Seti seeks, then either the signal is deliberate or accidental. An example of accidental is the electromagnetic radiation we send into space through radio and TV signals. According to tvtechnology.com “An average large transmitter transmits about 8kW per multiplex.” That will give “acceptable signal strength” over, say, 50 km. The signal strength attenuates according to the square of the distance, so while the signals will get to Alpha Centauri, they will be extremely weak, and because of bandwidth issues, broadcasts from well separated transmitters will interfere with each other. Weak signals can be amplified, but aliens at Alpha Centauri would get extremely faint noise that might be assignable to technology. 

Suppose you want to send a deliberate signal? Now, you want to boost the power, and the easiest way to get over the inverse square attenuation is to focus the signal. Now, however, you need to know exactly where the intended recipient will be. You might do this for one of your space ships, in which case you would send a slightly broader signal on a very high power level at an agreed frequency but as a short burst. To accidentally detect this, because you have a huge range of frequencies to monitor, you have to accidentally be on that frequency at the time of the burst. There is some chance of Seti detecting such a signal if the space ship was heading to Earth, but then why listen for such a signal, as opposed to waiting for the ship.

The next possible deliberate signal would be aimed at us. To do that, they would need to know we had potential, but let us suppose they did. Suppose it takes something like 4.5 billion years to get technological life, and at that nice round number, they peppered Earth with signals. Oops! We are still in the Cretaceous. Such a move would require a huge power output so as to flood whatever we were using, a guess as to what frequencies we would find of interest, and big costs. Why would they do that, when it may take hundreds or thousands of years for a response? It makes little sense for any “person” to go to all that trouble and know they could never know whether it worked or not. We take the cheap option of listening with telescopes, but if everyone is listening, nobody is sending.

How do they choose a planet? My “Planetary Formation and Biogenesis” concludes you need a rocky planet with major felsic deposits, which is most probable around the G type star (but still much less than 50% of them). So you would need some composition data, and in principle you can get that from spectroscopy (but with much better technology than we have). What could you possibly see? Oxygen is obvious, except it gives poor signals. In the infrared spectra, you might detect ozone, and that would be definitive. You often see statements that methane should be detectable. Yes, but Titan has methane and no life. Very low levels of carbon dioxide is a strong indication, as it suggests large amounts of water to fix it, and plate tectonics to renew it. Obviously, signals from chlorophyll would be proof, but they are not exactly strong. So if they are at anything but the very closest stars they would not know whether we are here, so why waste that expense. The Government accountants would never fund such a project with such a low probability of getting a return on investment. Finally, suppose you decided a planet might have technology, why would you send a signal? As Hawking remarked, an alien species might decide this would be a good planet to eradicate all life and transform it suitable for the aliens to settle. You say that is unlikely, but with all those planets, it only needs one such race. So simple game theory suggests “Don’t do it!” If we assume they are more intelligent than us, they won’t transmit because there is no benefit for those transmitting.

Ebook Discount

From June 25 – July 2, my thriller, The Manganese Dilemma, will be discounted to 99c/99p on Amazon. 

The Russians did it; everyone is convinced of that. But just exactly what did they do? Charles Burrowes, a master hacker, is thrown into a ‘black op’ with the curvaceous Svetlana for company to validate new super stealth technology she has brought to the West. Some believe there is nothing there since their surveillance technology cannot show any evidence of it, but then it is “super stealth” so just maybe . . . Also, Svetlana’s father was shot dead as they made their escape. Can Burrowes provide what the CIA needs before Russian counterintelligence or a local criminal conspiracy blow the whole operation out of the water? The lives of many CIA agents in Russia will depend on how successful he is.

Energy from the Sea. A Difficult Environmental Choice.

If you have many problems and you are forced to do something, it makes sense to choose any option that solves more than one problem. So now, thanks to a certain virus, changes to our economic system will be forced on us, so why not do something about carbon emissions at the same time? The enthusiast will tell us science offers us a number of options, so let’s get on with it. The enthusiast trots out what supports his view, but what about what he does not say? Look at the following.

An assessment from the US Energy Information Administration states the world will use 21,000 TWh of electricity in 2020. According to the International Energy Agency, the waves in the world’s oceans store about 80,000 TWh. Of course much of that is, well, out at sea, but they estimate about 4,000 TWh could be harvested. While that is less than 20% of what is needed, it is still a huge amount. They are a little coy on how this could be done, though. Wave power depends on wave height (the amplitude of the wave) and how fast the waves are moving (the phase velocity). One point is that waves usually move to the coast, and there are many parts of the world where there are usually waves of reasonable amplitude so an energy source is there.

Ocean currents also have power, and the oceans are really one giant heat engine. One estimate claimed that 0.1% of the power of the Gulf Stream running along the East Coast of the US would be equivalent to 150 nuclear power stations. Yes, but the obvious problem is the cross-sectional area of the Gulf Stream. Enormous amounts of energy may be present, but the water is moving fairly slowly, so a huge area has to be trapped to get that energy. 

It is simpler to extract energy from tides, if you can find appropriate places. If a partial dam can be put across a narrow river mouth that has broad low-lying ground behind it, quite significant flows can be generated for most of the day. Further, unlike solar and wind power, tides are very predictable. Tides vary in amplitude, with a record apparently going to the Bay of Fundy in Canada: 15 meters in height.

So why don’t we use these forms of energy? Waves and tides are guaranteed renewable and we do not have to do anything to generate them. A surprising fraction of the population lives close to the sea, so transmission costs for them would be straightforward. Similarly, tidal power works well even at low water speeds because compared with wind, water is much denser, and the equipment lasts longer. La Rance, in France, has been operational since 1966. They also do not take up valuable agricultural land. On the other hand, they disturb sea life. A number of fish appear to use the Earth’s magnetic field to navigate and nobody knows if EMF emissions have an effect on marine life. Turbine blades most certainly will. They also tend to be needed near cities, which means they disturb fishing boats and commercial ships.

There are basically two problems. One is engineering. The sea is not a very forgiving place, and when storms come, the water has serious power. The history of wave power is littered with washed up structures, smashed to pieces in storms. Apparently an underwater turbine was put in the Bay of Fundy, but it lasted less than a month. There is a second technical problem: how to make electricity? The usual way would be to move wire through a magnetic field, which is the usual form of a generator/dynamo. The issue here is salt water must be kept completely out, which is less than easy. Since waves go up and down, an alternative is to have some sort of float that mechanically transmits the energy to a generator on shore. That can be made to work on a small scale, but it is less desirable on a larger scale.The second problem is financial. Since history is littered with failed attempts, investors get wary, and perhaps rightly so. There may be huge energies present, but they are dispersed over huge areas, which means power densities are low, and the economics usually become unattractive. Further, while the environmentalists plead for something like this, inevitably it will be, “Somewhere else, please. Not in my line of sight.” So, my guess is this is not a practical solution now or anytime in the reasonable future other than for small specialized efforts.