Search-engine power
James Clarage’s calculations of Google’s energy usage assume that all their “nearly a million” servers do is perform searches (3 April, p 20).
In fact, Google uses these data centres for many things: hosting YouTube and Gmail, caching just about every web page in existence and being one of the world’s largest web advertisers are just a few of them. Google is estimated to constitute between 10 and 30 per cent of the entire internet. Clarage compares the cost of a search to the cost of switching on a 100-watt light bulb. If I had to choose between the light bulb and Google’s many services, I’d happily live in the glow of a million LEDs.
From Tim Rustige
James Clarage states that “Google serves up approximately 10 million search results per hour, and so each search costs the same as running a 100-watt electric light bulb for an hour”.
According to his figures, then, Google serves up 240 million searches a day. In fact they serve up around , around 3 billion a day.
It is my understanding that Google uses PCs for each server. I doubt that each of Google’s basic servers draws Clarage’s claimed 1 kilowatt of power; it would be something closer to 400 watts. And if Google has a million servers, as Clarage reports, then from his own figures, each one would only perform 10 searches an hour. This sounds like underuse to me. Maybe only a small fraction of those million servers search, while the rest serve up Gmail, Adwords or YouTube videos.
Knutsford, Cheshire, UK
James Clarage writes:
鈥� The figures used in my estimate for the number of servers, and searches per hour, were for US traffic only. Worldwide traffic is of course higher, but so proportionally is the number of mirror-servers around the globe which handle this traffic. My kilowatt estimate for a server includes additional thermal factors, such as cooling, as well as the server’s power supply. Finally, the servers do not sit idle when not performing a search; they are busy downloading and indexing one of the world’s largest datasets.
Journal for rejects
In her letter on the ability of the peer-review process to effectively challenge scientific dogma, Deepa Coleman notes that “there is no such person as a disinterested scientist”. In the next letter, Bruce Denness states: “What peer review guarantees is the attainment of mediocrity in the most efficient way” (20 March, p 24).
Combining the two, it seems we need a peer-reviewed journal exclusively for heretics. In 1971 I suggested a journal for just this purpose, called Reject. It would only publish papers that had previously been rejected by three existing journals.
As a postdoctoral fellow at the time, my latest paper had suffered exactly this fate. When I looked at the editorial boards for the journals, I could understand why: if I was right, then a lot of people were wrong. The paper was eventually published, unchanged, in a more prestigious journal, which suggests Reject would play host to controversial, but also reputable, research.
Forty years on, nothing much seems to have changed. Certainly, no one has been game enough to publish Reject.
Island reborn
In discussing the conservation management of Cousin Island (24 April, p 36), Graham Lawton says the island was bought from “the Seychelles royal family” in 1968. In fact, the island was purchased by BirdLife International from a , whose husband had run it as a coconut plantation.
The article is also mistaken in saying “most of the plants on Cousin are now endemics”. Most are actually pan-tropical coastal species, presumably but not necessarily native, with few endemic to the Seychelles and none endemic to Cousin.
Certainly many of the alien plants that were common when I lived there in the 1970s are now gone or very much rarer. I don’t think that pawpaw trees need to be removed, as suggested by the chief executive of Nature Seychelles. The canopy will shade it out quite quickly, and native Seychelles birds called fodies (Foudia sechellarum) are very keen on the fruit.
Tired to death
In your compendium on human endurance, Graham Lawton asserts that there are no records of a person having been killed by intentional sleep deprivation (17 April, p 37).
There may not have been any scientific experiments, but there is a well-documented case from classical history. Perseus, the last king of Macedon, after being captured and imprisoned by the Romans in 166 BC, “offended the barbarians who were his guards, and was prevented from sleeping until he died of it”, according to ‘s Bibliotheca Historica.
Military innovation
Ian Gilbert cites many examples of how civilian life has benefited from military scientific advances (17 April, p 25) but he misses a subtle point: military spending does not in itself increase the number of innovators, it just excludes them from the constraints of the civilian market. Military activity itself depends on the existence of an underlying peaceful economy. The real question is: how can we have the same benefits without such a destructive vehicle?
Solar payback
In calculating the payback times for investment in alternative energy systems (27 March, p 46), Ed Douglas used an erroneous assumption. He stated, for example, that payback for the photovoltaic system costing 拢11,000 would take 55 years, so that you recoup 拢200 per year. Such calculations assume that a single rate of inflation applies uniformly to everything 鈥� but this is not necessarily the case.
Say I have 拢11,000. I could put the money in a savings account and earn 3 per cent interest, but I don’t think I can trust the vagaries of the stock market and I am also worried about escalating energy costs. I make a guess that electricity costs will begin to rise faster than they do today, inflating at 12 per cent per year as society is weaned off oil. If I invest my money in a solar power system under these circumstances, then in only 24 years I will have recovered my capital outlay and the interest I would have earned from the savings account.
That is still a long time, but far better than 55 years. The investment would also provide benefits such as a measure of security against future energy crises. There are only two questions to answer before I go ahead. First, photovoltaic costs are falling, so when is the best time to buy the panels? And what is the useful life of the panels?
From John Kirby
I was concerned that Ed Douglas’s article on ways to make homes more energy-efficient (27 March, p 46) did not refer to the “feed-in-tariffs” 鈥� the price homeowners receive for renewably generated electricity they sell to the grid 鈥� that apply in some countries, including the UK. As these will affect how long it takes to recoup the installation costs of a renewable system, it would have been nice if they could have been included in the payback times in the diagram showing ways of making your house eco-friendly.
Nottingham, UK
Grumpy or honest?
Wendy Zukerman reports that old folks might be grumpier than younger people because their brains have a reduced ability to cope with stress (10 April, p 10). Being in my mid-70s, I have considered the question at length. My theory is that, as we become increasingly aware of our mortality, we redefine the things that are important to us. The result is most obviously observed in our level of acquiescence to other people’s wishes.
I have mastered the art of responding truthfully to invitations to participate in what I would consider boring or annoying activities: I say that I don’t want to, rather than make up some excuse. Such reactions are deemed to be antisocial and I am labelled as being grumpy. Such is the price of honesty.
Brain box
Miroslav Hundak states that physical changes in the brain create variations in conscious experience, proving that consciousness must be controlled by the physical properties of the brain (10 April, p 24).
However, if we take a mechanistic analogy we see that the correlation may not be causal. An engine could be running perfectly, despite being impossible to observe or study. If its linkages and gears are damaged or altered then its interactions with the external world would change. A person unaware of the engine’s existence might believe that the gears are in fact the engine, but that would not be the case.
Damage to the brain, which can alter the awareness of consciousness, is no more than a sign that when the machinery used to access consciousness is damaged, the experience of consciousness changes. It does not prove that the brain is the source of consciousness. It may well turn out that body/mind duality is an illusion, but the statement that damage to one proves the non-existence of the other is not evidence.
Wasted efforts
I read with interest the article about the “brainstorming” session sponsored by MIT and Sandia National labs last month in Washington, DC. Phil McKenna wrote that the “world’s leading experts” on using boreholes to bury nuclear waste got the idea that with this disposal method we could safely bury radioactive material all over the US (3 April, p 9).
Given that this would also require the public transport by highway and rail of nuclear waste all over the US, I have an idea, too: let’s not do that. The probability of an accident is 100 per cent.
Here in the US, depending on whose numbers you believe, we waste between 30 per cent and 50 per cent of the energy we consume. Why don’t we just stop doing that instead?
For the record
鈥� Contrary to the caption for the map in our article on mass extinction, Jersey is one of the Channel Islands, and is not part of the UK (24 April, p 38).
鈥� It is hydroxyl radicals, rather than ions, that would oxidise sulphur dioxide emitted from the Toba supervolcano (17 April, p 28).
鈥� In our article on endurance, we mispelled the name of world record holder Stephane Mifsud (17 April, p 34).