Anhinga anhinga

Milorad Pavić died

Tue, 01 Dec 2009 21:06:32 GMT

http://en.wikipedia.org/wiki/Dictionary_of_the_Khazars
http://ru.wikipedia.org/wiki/Хазарский_словарь

"ЛОВЦЫ СНОВ - секта хазарских священнослужителей,
покровителем которых была принцесса Атех. Они умели читать
чужие сны, жить в них как в собственном доме и, проносясь сквозь
них, отлавливать в них ту добычу, которая им заказана, -
человека, вещь или животное. Сохранились записки одного из самых
старых ловцов снов, в которых говорится: "Во сне мы чувствуем себя
как рыба в воде. Время от времени мы выныриваем из сна,
окидываем взглядом собравшихся на берегу и опять погружаемся,
торопливо и жадно, потому что нам хорошо только на глубине. Во
время этих коротких появлений на поверхности мы замечаем на
суше странное создание, более вялое, чем мы, привыкшее к другому,
чем у нас, способу дыхания и связанное с сушей всей своей
тяжестью, но при этом лишенное сласти, в которой мы живем как в
собственном теле. Потому что здесь, внизу, сласть и тело
неразлучны, они суть одно целое. Это создание там, наверху, тоже
мы, но это мы спустя миллион лет, и между нами и ним лежат не
только годы, но и страшная катастрофа, которая обрушилась на
того, наверху, после того как он отделил тело от сласти..."

Одного из самых известных толкователей снов, как говорит
предание, звали Мокадаса аль Сафер.Он сумел глубже всех
приблизиться к проникновению в тайну, умел укрощать рыб в
чужих снах, открывать в них двери, заныривать в сны глубже всех
других, до самого Бога, потому что на дне каждого сна лежит Бог. А
потом с ним случилось что-то такое, что он больше никогда не смог
читать сны. Долго думал он, что достиг совершенства и что дальше в
этом мистическом искусстве продвинуться нельзя. Тому, кто
приходит к концу пути, путь больше не нужен, поэтому он ему и не
дается. Но те, кто его окружал, думали иначе. Они однажды
рассказали об этом принцессе Атех, и она объяснила им, что
случилось с Мокадасой аль Сафером:

- Один раз в месяц, в праздник соли, в пригородах всех наших
столиц приверженцы хазарского кагана бьются не на жизнь, а на
смерть с вами, кто меня поддерживает и кого я опекаю. Как
только падает мрак, в тот час, когда погибших за кагана хоронят
на еврейских, арабских или греческих кладбищах, а отдавших
жизнь за меня погребают в хазарских захоронениях, каган тихо
открывает медную дверь моей спальни, в руке он держит свечу,
пламя которой благоухает и дрожит от его страсти. Я не
смотрю на него в этот миг, потому что он похож на всех
остальных любовников в мире, которых счастье будто ударило по
лицу. Мы проводим ночь вместе, но на заре, перед его уходом, я
рассматриваю его лицо, когда он стоит перед отполированной
медью моей двери, и читаю в его усталости, каковы его намерения,
откуда он идет и кто он таков.

Так же и с вашим ловцом снов. Нет сомнений, что он достиг
одной из вершин своего искусства, что он молился в храмах чужих
снов и что его бесчисленное число раз убивали в сознании видящих
сны. Он все это делал с таким успехом, что ему начала
покоряться прекраснейшая из существующих материй -
материя сна. Но даже если он не сделал ни одной ошибки,
поднимаясь наверх, к Богу, за что ему и было позволено видеть Его
на дне читаемого сна, он, конечно же, сделал ошибку на обратном
пути, спускаясь в этот мир с той высоты, на которую вознесся.
И за эту ошибку он заплатил. Будьте внимательны при
возвращении - закончила принцесса Атех. - Плохой спуск может
свести на нет счастливое восхождение.

Firefox add-ons: WebPredict, TooManyTabs

Sat, 21 Nov 2009 00:54:09 GMT

I'd like to review a couple of Firefox add-ons I am using every day: our own WebPredict, and TooManyTabs. Both are intended for people who browse a lot.

WebPredict allows user to rate some Web pages, and based on those ratings predicts the quality of other Web pages. We made a beta-release of this add-on recently, and this beta-release prompted me to write this review.

The add-on is here https://addons.mozilla.org/en-US/firefox/addon/14273, and the server site (if/when one needs it) is http://www.webpredict.net/wp.

One can either choose to use this add-on anonymously or to create a WebPredict account. Both choices can be made via the right-click mouse menu, and if one wants to rate the page one is reading, this can also be done via the right-click menu.

There are various ways to ask for prediction of the quality of the page. One can hover over a link and press 'p' to obtain the prediction for the page behind the link. One can use Tools command in the browser menu to see more commands associated with this add-on, including "Predict Current Page" (this command has Ctrl+Alt+Shift+P shortcut; another shortcut I often find useful is Ctrl+Alt+Shift+C to clear WebPredict messages).

I usually set "Auto Predict Current Page" via add-on Options, and then the add-on tells me automatically what it thinks about the current page, but many people might find this too intrusive, so this is not on by default. One can also use add-on Options to set "Predict by Mouse Hovering", then simply hovering over the link would trigger the prediction.

Pressing '.' while hovering over the link allows to display prediction for multiple links around the current one (Ctrl+Alt+Shift+L would display predictions for multiple links around the cursor). Predicting links might not work if a Web site scrambles its page (unfortunately, Google does scramble its search results, and we don't handle this yet).

An anonymous user gets default settings, which are reasonably similar to the setting I am using for myself. If one creates an account one can go to the server page and tune one's rating categories and prediction settings in all kinds of ways (we do try to open our engine to the users, although for now we just provide a lot of knobs to control and tune it). If one creates an account, one can share ratings between different computers. If one first works anonymously and then creates an account, the ratings made anonymously are inherited.

I currently have about 25 ratings, and predictions usually correlate well with my own estimates. (When they don't, basically, when I feel the model does not rate a page correctly, is when I add a rating for the page in question.)

This is still experimental. We are trying to see whether it is useful in its current form, and what should be done to make it more useful/popular.

TooManyTabs allows user who has too many tabs to save tabs, so that they don't eat memory and don't slow down the browser.

The add-on is here: https://addons.mozilla.org/en-US/firefox/addon/9429, and this is its home page: http://www.visibotech.com/toomanytabs.

It allows you to manage multiple rows of saved tabs. It saves both the URL and your scrolling state. You can backup your tabs into a file in JSON format and restore from such a file. So you have your URLs in a plain text form, and you can even exchange your saved tabs between computers.

Note that memory management in Firefox is still quite imperfect, and the memory often is not released as you close the windows. This means that if you have too many tabs, and this slows your browser down, and you save some of them using TooManyTabs add-on to free some memory and to make it faster, you might still need to restart the browser in order to see the improvement.

I should say that this add-on makes my life much better. I can keep the tabs I like without losing them, and still have a browser which works fast. Nevertheless, I am still looking for better tools to manage large collections of URLs.

t

Sat, 07 Nov 2009 05:02:02 GMT

The strangest impression from my October trip to Moscow was mainstreaming of Pelevin. The ads for his new novel, "t", were on subway escalators, the book itself was featured prominently in airport book kiosks. I always thought that his attempts to popularize some rather difficult concepts from non-Western philosophy would automatically limit his audience, so this was a great surprise.

The book itself seemed to be structured into dozens of quite different realities. I liked it a lot, but then I usually like his books.

Another impression was that air quality in Moscow was much better than 11 months ago. I did not know what combination of recession, emission enforcement, or simply luck was responsible for that, but the improvement was dramatic.

On a more personal level, I now often recognize/hallucinate various Moscow smells here in Boston.

Since I started to talk about "t", I want to write a bit about treatment of time in the "Quantum Gravity" book I mentioned in the previous post. The most interesting is his "Thermal time hypothesis", a conjecture that time is on its fundamental level induced by the thermodynamic considerations. This starts on page 117 of the PDF file, page 99 of the book. This conjecture is an interesting, "dual" answer to questions about nature of the time arrow and its possible relation to thermodynamics people like Penrose and Prigogine were asking. Rovelli suggests that there might be no notion of time on more fundamental levels than the level of thermodynamics.

I also recommend the review of various meanings of time starting from page 76 of the PDF file, page 58 of the book, and up to the table of all meanings of time he discusses on page 79 of the PDF file, page 61 of the book.

Of interest is also his proposed relational interpretation of quantum theory, starting from page 168 of the PDF file, page 150 of the book. All fragments I mention here are written so that they can be understood by non-physicists.

And it is great to use a netbook with battery life sufficient to last for 8 or 9 hour in flight to read a book like this. United Airlines sucks, however, -- flight cancellation, 24 hour delay of travel.

Carlo Rovelli, "Quantum Gravity"

Mon, 12 Oct 2009 04:31:26 GMT

'(Newtonian) space was the "sensorium" of God, the World as perceived by God.'

Section 10.1.3, "Space, time and unitarity", page 267 of the book, page 285 of the PDF file:

http://www.cpt.univ-mrs.fr/~rovelli/book.pdf (4.6MB)

linked from

http://en.wikipedia.org/wiki/Loop_quantum_gravity

This is the only textbook on loop quantum gravity and it can actually be partially understood by non-physicists. For example, in mid-90s I was trying to imagine how one could have discrete space at the quantum scale, but so that it still appears continuous at the macroscopic level. All variants I could come up with were pretty ugly. This book contains a very neat construction of that.

(Section 1.2.2. Quantum space: spin networks, starting from page 12 of the book, page 30 of the PDF file.)

Basically, when one measures any volume precisely enough, it should take a discrete value. Then some volumes (grains of space) are adjacent to each other, and the area of surface dividing two grains should also take a discrete value.

So the state is represented by a graph, the nodes are the grains of space labeled with discrete volume values, and the edges connect adjacent grains and are labeled with discrete surface area values.

This structure is called an "abstract spin network". The actual physical space is a quantum superposition of such spin networks.

More on perception of conscious will

Tue, 22 Sep 2009 02:42:28 GMT

The perception of conscious will is an inference. Daniel Wegner demonstrated a while ago, that it is easy to create experimental setups, where the subject has illusion of freely causing events, which are completely independent of his actions or intentions.

cognitivedaily is reporting on an experiment, which sheds some extra light on the inference of conscious will:

http://scienceblogs.com/cognitivedaily/2009/09/free_choice_may_not_be_as_free.php

Here, the subject presses the button, and the beep sounds as a result, but a random delay is added between pressing the button and the resulting beep sound. Then the subject is asked to pinpoint the moment of time, when the decision to press the button was made. It turns out that subjects on average estimate that moment as approximately 130 milliseconds before the beep sound (and that the estimate depends very weekly on the actual time when the subject pressed the button).

So this is another illustration how the inference of conscious will uses the observation of the physical event which is (apparently, and in this case, actually) caused by the subject. Wegner's experiments were also based on this, only in his case the event only seemed to be caused by the subject, while in this case the causation is real, but a random delay is inserted.

I was trying to interpret the 130 millisecond number, which seems to be pretty close to the characteristic time intervals for visual perception, or motor control signal propagation. Of course, it is difficult to say anything conclusive. But this time interval might be close to the "correct estimate" of the interval between the initiation of motor control neural circuits and the actual movement in "naturally occurring situations".

Russian in Linux (UTF-8)

Fri, 04 Sep 2009 22:30:00 GMT

Last spring I have posted an Emacs trick allowing to edit Russian texts and to include Russian substrings into the command line.

It turns out that there is a much simpler way to accomplish these tasks. Just set LANG variable to en_US.UTF-8 and this should enable you to use Russian UTF-8 in vi editor and in a number of other programs (e.g. PostgreSQL interactive sessions).

This assumes that something like LC_ALL does not override LANG (in which case set it to en_US.UTF-8 as well), and that you are working inside a UTF-8 capable terminal window, and the encoding in the terminal window is set to be UTF-8.

If the command line input of Russian UTF-8 character is broken, set LANG variable to en_US.UTF-8 and then open a new shell. (In this case just setting the variable does not seem to fix what was broken during shell initialization, so the initialization needs to be repeated; at least, it looks this way when one uses bash under Debian.)

It turns out that grep is UTF-8 capable these days: grep "Привет" filename works fine.

Remark: this still does not interpret the keyboard keys as Russian, unlike the Emacs trick. These days I usually just get the Russian strings I need by typing them somewhere in Firefox using the RussKey addon (and then just selecting them by the mouse and pasting them by the middle key of the mouse, when I am under Gnome environment on a Debian Linux machine).

Remark: in Gnome terminal, one can use Right-mouse-click - Input Methods to switch between Cyrillic translit and default (thanks to miserakl for this remark).

"Placebos are getting more effective"

Thu, 27 Aug 2009 04:22:12 GMT

http://www.wired.com/medtech/drugs/magazine/17-09/ff_placebo_effect?currentPage=all

"Some products that have been on the market for decades, like Prozac, are faltering in more recent follow-up tests. In many cases, these are the compounds that, in the late '90s, made Big Pharma more profitable than Big Oil. But if these same drugs were vetted now, the FDA might not approve some of them. Two comprehensive analyses of antidepressant trials have uncovered a dramatic increase in placebo response since the 1980s."

The whole article is a bit too long, which is typical for "Wired".

Some highlights:

* "[...]What they found challenged some of the industry's basic assumptions about its drug-vetting process.

Assumption number one was that if a trial were managed correctly, a medication would perform as well or badly in a Phoenix hospital as in a Bangalore clinic. Potter discovered, however, that geographic location alone could determine whether a drug bested placebo or crossed the futility boundary. By the late '90s, for example, the classic antianxiety drug diazepam (also known as Valium) was still beating placebo in France and Belgium. But when the drug was tested in the US, it was likely to fail. Conversely, Prozac performed better in America than it did in western Europe and South Africa. It was an unsettling prospect: FDA approval could hinge on where the company chose to conduct a trial."

* "US scientists had found that a drug called naloxone blocks the pain-relieving power of placebo treatments. The brain produces its own analgesic compounds called opioids, released under conditions of stress, and naloxone blocks the action of these natural painkillers and their synthetic analogs."

* "[...]the geographic variations in trial outcome that Potter uncovered begin to make sense in light of discoveries that the placebo response is highly sensitive to cultural differences. Anthropologist Daniel Moerman found that Germans are high placebo reactors in trials of ulcer drugs but low in trials of drugs for hypertension—an undertreated condition in Germany, where many people pop pills for herzinsuffizienz, or low blood pressure. Moreover, a pill's shape, size, branding, and price all influence its effects on the body. Soothing blue capsules make more effective tranquilizers than angry red ones, except among Italian men, for whom the color blue is associated with their national soccer team—Forza Azzurri!"

* "But why would the placebo effect seem to be getting stronger worldwide? Part of the answer may be found in the drug industry's own success in marketing its products."

* "Ten years and billions of R&D dollars after William Potter first sounded the alarm about the placebo effect, his message has finally gotten through. In the spring, Potter, who is now a VP at Merck, helped rev up a massive data-gathering effort called the Placebo Response Drug Trials Survey.

Under the auspices of the NIH, Potter and his colleagues are acquiring decades of trial data—including blood and DNA samples—to determine which variables are responsible for the apparent rise in the placebo effect. Merck, Lilly, Pfizer, AstraZeneca, GlaxoSmithKline, Sanofi-Aventis, Johnson & Johnson, and other major firms are funding the study, and the process of scrubbing volunteers' names and other personal information from the database is about to begin.

In typically secretive industry fashion, the existence of the project itself is being kept under wraps. NIH staffers are willing to talk about it only anonymously, concerned about offending the companies paying for it."

Duality between metric and logical viewpoints

Wed, 05 Aug 2009 15:53:00 GMT

The metric viewpoint: how far two objects are from each other. The logical viewpoint: to what degree two objects overlap.

Fuzzy mathematics is traditionally done from the logical viewpoint, so the first step in introducing fuzzy metrics is often the transformation f(x,y) = exp(-d(x,y)).

Then we have the following correspondences:

d(x,y) = 0 if and only if f(x,y) = 1.

d(x,y) is plus infinity if and only if f(x,y) = 0.

d(x1, y1) < d(x2, y2) if and only if f(x1, y1) > f(x2, y2).

The axiom d(x,x) = 0 becomes f(x,x) = 1.

The axiom d(x,z) < d(x,y) + d(y,z) becomes f(x,y) * f(y,z) < f(x,z).

Non-expansive maps become maps which respect overlap by not letting it decrease.

Etc..

However, this seems to be a rather superficial duality: basically two equivalent ways to write the same things using different notation.

The question is whether there is also a natural deeper duality here (of a contravariant nature, where function arrows would reverse direction when one switches between these two viewpoints).

Скульптуры из воды

Tue, 28 Jul 2009 23:41:53 GMT

http://nature-wonder.livejournal.com/167564.html

В том же журнале хорошая выдержка из беседы с К.Еськовым про эволюцию:

http://nature-wonder.livejournal.com/167238.html

From a workshop on role of theory in design automation

Thu, 09 Jul 2009 20:50:32 GMT

"One of the recurrent themes of the discussion is: we have SAT solvers that seem to work on all examples we try them on. How does this fit with the conventional wisdom that P not equal to NP? This is a very interesting open problem, that we should work on in the future."

from http://rjlipton.wordpress.com/2009/07/09/nsf-workshop-summary/ via rjlipton

Rowan Tree: photos

Fri, 29 May 2009 22:21:31 GMT

http://users.livejournal.com/_rowan_tree_/tag/фото

Anti-angiogenesis drugs :-(

Wed, 27 May 2009 21:25:08 GMT

I still remember time when great hopes in anti-cancer therapy were raised in connection with drugs blocking formation of new blood vessels. And (as it is often the case) the results in mice were great.Then the hopes dimmed, and the controversial approval of Avastin by FDA in 2008 against the recommendation of its advisory panel underscored the fact that the advances were quite marginal (the panel objected because for that class of tumors Avastin only slowed tumor growth but failed to extend survival):

http://en.wikipedia.org/wiki/Bevacizumab

Here is an article which seems to shed some light on why the "magic bullet" does not quite work:

http://scienceblog.cancerresearchuk.org/2009/03/22/anti-angiogenesis-drugs/

In this particular case, very low doses of the chemical in question (cilengitide) instead promote the formation of new blood vessels and growth of tumor, and, unfortunately, the concentration in the tissue is quite non-uniform, both time-wise and in terms of distribution in the different areas of the body, so the patient would often have at least some areas of very low concentration of the chemical, with the adverse effect in those areas.

These negative results are still quite early, and it's not clear how general these new results are (e.g. whether they hold for Avastin), but I think this sheds some light on the situation.

Карликовый тушканчик/Pygmy jerboa

Wed, 27 May 2009 00:05:29 GMT

http://www.youtube.com/watch?v=PJnn-wMPU9w

Маленькие зелёные человечки среди нас..

http://en.wikipedia.org/wiki/Jerboa

http://ru.wikipedia.org/wiki/Тушканчиковые

via Andrew Sullivan

The Boston Globe to close?

Tue, 05 May 2009 15:58:44 GMT

"The New York Times Co. said last night that it is notifying federal authorities of its plans to shut down the Boston Globe."

via http://althouse.blogspot.com/2009/05/death-of-boston-globe.html

upd: probably not, this is just a labor dispute.

Scanning laser ophthalmoscopy

Fri, 17 Apr 2009 19:28:38 GMT

Now the eye exam can be made without eye drops which dilate the pupils, so one can read or drive afterwards. Another good thing is that the resulting pictures are stored, so it is possible to track the changes over the years.

And the pictures are pretty cool and resemble some of pictures obtained from space telescopes, which is not so surprising, since the same methods of adaptive optics are used:

http://www.totalfamilyeyecare.com/optos.htm

http://en.wikipedia.org/wiki/Scanning_laser_ophthalmoscopy

There still were couple of downsides. My vision care insurance would pay for the dilation, but would not cover these photos, so it was $39. And I did not get the e-mail with those photos (at least, not yet).

Biological inheritance of changes from mental training?

Tue, 31 Mar 2009 18:02:05 GMT

http://www.ncbi.nlm.nih.gov/pubmed/19193896

via http://community.livejournal.com/free_times/181822.html

D. Gabor, Associative Holographic Memories

Fri, 27 Mar 2009 21:11:41 GMT

I recently found a very cool short paper (4 pages) which Dennis Gabor written 40 years ago.

It explains the math of associative holographic memory, which turns out to be very simple.

Because it is that simple, neither holograms, nor even waves and oscillations, are actually necessary to implement this scheme of associative memory.

D. Gabor, Associative Holographic Memories, IBM Journal of Research and Development, 13(2), 156-159 (1969). Abstract, PDF

Undersea eruptions near Tonga, March 19

Sun, 22 Mar 2009 21:08:02 GMT

Photos are here:

http://vladimirpotapov.livejournal.com/798634.html

A larger set:

http://www.boston.com/bigpicture/2009/03/undersea_eruptions_near_tonga.html

flash mob

Sun, 04 Jan 2009 19:33:35 GMT

Возьми ближайшую книгу.
Открой на странице 123.
Найди третье предложение.
Помести его в своём ЖЖ вместе с этими инструкциями.

So the entropy of the whole system is less then the entropy of the two coordinates added together, and the amount by which it is less is exactly the mutual information: I_mutual = S[X] + S[Y] - S[X, Y].

(via http://yan.livejournal.com/1509810.html)

"Towards a Neurobiological Theory of Consciousnes"

Wed, 31 Dec 2008 20:52:47 GMT

Recently, I reread a number of papers in neuro. The one I liked the most is "Towards a Neurobiological Theory of Consciousness" by Francis Crick and Christof Koch in Seminars in the Neurosciences (1990), Volume 2, pages 263–275:

http://profiles.nlm.nih.gov/SC/B/C/F/D/_/scbcfd.pdf

*****

The "Crick-Koch Conjecture" is that the difference between conscious and unconscious processing is that in the conscious processing the relevant neurons fire in synch, producing (gamma) oscillations. Basically, the conjecture is that the temporal synchrony of the relevant action potentials is what creates a conscious sensation.

This is not the first time people were trying to link neural oscillations and synchrony with consciousness. However, whether this conjecture is right or wrong, after this paper it again became acceptable to address and study the issues of consciousness in the mainstream neuroscience. The reason is probably the combination of Crick's reputation (he achieved seminal breakthroughs quite a few times in his life) and of the fact that this paper is very well and clearly written. If someone wants to read one paper in theoretical neuroscience, this is probably the paper to read.

Crick and Koch remark that one does not need to formally define consciousness in order to study it: "Everyone has a rough idea of what is meant by consciousness. We feel that it is better to avoid a precise definition of consciousness because of the dangers of premature definition. Until we understand the problem much better, any attempt at a formal definition is likely to be either misleading or overly restrictive, or both."

*****

I hope the next year will be better than the outgoing one...

Good luck in the New Year!

Best of Abstruse Goose

Tue, 30 Dec 2008 23:19:55 GMT

http://abstrusegoose.com/80

http://abstrusegoose.com/8

http://abstrusegoose.com/31

http://abstrusegoose.com/48

http://abstrusegoose.com/56

http://abstrusegoose.com/59

http://abstrusegoose.com/73

History of Christmas in America

Fri, 26 Dec 2008 04:19:20 GMT

"Whosoever shall be found observing any such day as Christmas or the like, either by forbearing of labor, feasting or any other way . . . shall pay for every such offense five shillings, as a fine to the county."

1659, Massachusetts General Court

Дмитрий Крымов

Fri, 12 Dec 2008 23:03:48 GMT

Одно из самых интересных московских впечатлений -- двойной спекталь Дмитрия Крымова в Школе Драматического Искусства на Сретенке, "Родословная" и "Шостакович":

http://info.sdart.ru/item/603

"Родословная" -- особенно яркая. Название "спектакль" или "театр" применимо к тому, что он делает, довольно условно, поскольку он использует элементы разных жанров, и у меня нет впечатления, что драматургия -- основная компонента, а остальные -- вспомогательные. Если верить их сайту, то у них еще есть билеты на 14-17 декабря и 24-26 января..

Еще я видел очень яркую выставку Оскара Рабина в филиале Третьяковки около Парка Культуры, но она уже кончилась..

Steven Chu

Fri, 12 Dec 2008 02:44:32 GMT

It looks like a real scientist will be our next Secretary of Energy:

http://en.wikipedia.org/wiki/Steven_Chu

(Director of the Berkeley Lab, Nobel Prize for laser cooling and trapping of atoms)

Laser weapons are here

Thu, 20 Nov 2008 03:51:30 GMT

Northrop Grumman says its new 15kW FIRESTRIKE continuous fire solid-state laser is ready for orders by US military services.

A 400lb relatively compact device, can be combined into a 100kW battery, continuous run-time as long as power and coolant are provided, "designed as a line replaceable unit (LRU) for battlefield applications".

"Energy efficiency for Northrop's chains is supposedly in the 20 per cent region. This suggests that a full-bore 100kW battle ray will weigh about 1.5 tonnes and require half a megawatt of power.. within the ballpark for modern combat vehicles."

http://en.wikipedia.org/wiki/FIRESTRIKE
http://www.irconnect.com/noc/press/pages/news_releases.html?d=154600
http://www.theregister.co.uk/2008/11/14/weaponised_rayguns_hit_shelves_in_time_for_xmas
http://gizmodo.com/5088023/firestrike-is-worlds-first-battlefield-solid+state-laser-available-to-order-now

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Science fiction is becoming reality..