The Beta Mount?

The trend in consumer camera sensors seems to be heading towards greater on-chip processing and capabilities due to CMOS active pixel sensor (APS) architecture. This has now filtered upstream to DSLRs in the form of Live View, the ability to see a video frame-rate output from the sensor before final image capture. Sony have been pushing hard recently with parallel column ADC in order to increase readout rate and simultaneously lower readout noise. It is not inconceivable that in the near future, an interchangeable lens camera based on the alpha mount and lenses will be developed which omits the reflex mirror of a DSLR, replacing framing, AF and AE functions by Live View and a suitable electronic viewfinder (EVF).

For this to happen, several things need to be improved. The video refresh rate should be 60 fps or higher to allow accurate tracking and to avoid the feeling of lag. The power consumption should be low, comparable or lower than the power consumed by AF and AE. The EVF needs to have sufficiently high resolution to allow for manual focusing. To reproduce the viewfinder size and magnification of the Dynax 7, for example, may require something on the order of 2MP, roughly HDTV resolution. The technology is getting there, the same technology which is going into HDTV projectors could be adapted for EVF displays. The parallel column ADC approach allows greater flexibility in readout modes.

There are several advantages from a manufacturing point of view, by forgoing the reflex mirror and pentaprism, considerable bulk, mass and mechanical complexity can be eliminated leading to cheaper, lighter, and potentially more reliable cameras. Electronic shuttering would allow flash sync at all shutter speeds, viewfinder blackout would be reduced, and the frame rate would not be limited by mechanical parts. Noise and vibration would also be reduced leading to quieter and sharper operation. Live view would improve exposure and allow detailed manual focusing. Of course, there will be reluctance from traditionalists, perhaps sceptical about the clarity and responsiveness of EVFs, but the time may come where these objections may be overcome by improvements in electro-optics.

So presupposing sufficiently good EVFs and sensor performance, we can ask how best to adapt the Alpha mount to such a system. The absence of a mirror box means that the lens mount can be located much closer to the sensor. New lenses, especially wide angle lenses could take advantage of such geometry obviating the need for retrofocus design. However, the alpha mount and lenses are designed for a 44.5 mm distance between flange and sensor plane, meaning that these could not be directly used on such a short mount. The answer would be to design an adapter, basically an extension tube which would convey all the focusing and communication between body and lens. In this way, full compatibility could be maintained with existing lenses yet allow for optimised designs to take advantage of the reduced mount distance.

The new mount, for the purposes of this discussion called the Beta mount, could have a flange to sensor plane distance considerably shorter than the Alpha mount. Rangefinders have mount distances about half that of SLRs, 27.95mm (Leica M) vs 46.5mm (Nikon F). The Beta mount could have a mount distance even shorter, say 20mm, leaving enough room for adapters for all other mounts.

Beta mount lenses could follow EF lens design and have focusing and aperture electronically controlled by the body with power supplied by the body. This would further reduce the mechanical complexity of the body as well as simplifying the mechanical design of the mount. For alpha mount lenses attached via the adapter, focusing and aperture control could be retained by incorporating actuators within the adapter itself.

All of the above is speculation but could represent an avenue for Sony to make the best use of the advances in electro-optics yet maintain compatibility with legacy users.

More Sony Speculations

Warning: Take the following with a large grain of salt. I do not think that this will have a very high chance of actually occurring but might just represent one possible avenue for Sony to develop their Alpha system.

I have already made a few predictions about what I expect and hope the Advanced Amateur camera will be like. I will make a few predictions about what the Flagship camera may be like when it is rumoured to come out some time next year, possibly at photokina. The primary focus will be on the sensor. I do not think that the sensor in the D3 will be used in a Sony body. The conventional readout using 12 high speed ADCs does not fit in with the sensors that Sony are developing. The coyness of Nikon to name the manufacturer also indicates that Sony has had very little input into the sensor.

If the size of the Flagship sensor is as expected (36mm x 24mm), I expect that it will be based upon the IMX021 and thus would be 28MP with a pixel pitch of 5.49 microns. It would have column parallel ADC readout giving 7fps if a suitable mechanism is found for AF and AE, either by a suitably beefed up reflex mirror or Live View. It may deliver 14 bit RAW files, not neccessarily because the DR warrants it but because of marketing concerns. Super Steady Shot will be included, the PMA presentation reinforced Sony's committment to providing this. There are no show-stopping problems in implementing this for a 135-sized sensor, merely a matter of mass, power, sufficient image circle (135-format lenses tend not to have a perfectly sharp-edged 43.3 mm image circle but have sufficient margin to allow for sensor movement) and control strategy.

Several shooting modes would be available, including a 7MP 14fps mode, either cropped to APS-C size or a subsampling of whole frame. These would be in Live View mode. A selectable 12/14 bit RAW file would also be provided. For single shot mode, a high precision sampling option would reduced frame rate but possibly justify the 14 bit RAW file. It's pretty safe to say that the image buffer will be large, possibly 1GB giving 20 RAW or 100 JPG shots. Sony may use a DNG file format, losslessly compressed. Other possible features are weather sealing, 100% viewfinder, interchangeable viewscreens, wireless transfer and control, and geotagging (GPS).

With the Flagship, Sony will want to make a strong statement. By providing the highest pixel count in a 35mm-style DSLR, Sony would signify its committment to the Alpha mount. Coupled with Zeiss optics, the combination would be a serious professional set-up.

Nikon's D3 and D300: Implications for Sony?

Nikon shooters have had some very good news today, the long awaited and rumoured D3 and D300 have been unveiled to a rapturous audience. They both boast impressive specifications and many other sites have covered these in depth so I won't reproduce them here. I will speculate and point out some features of the new Nikons which may have some bearing on Sony's DSLR efforts. Given the long history between Nikon cameras and Sony sensors, hopefully the latest information on the new models will provide some insight into the machinations behind Sony's closed doors.

We'll start with the D3. From Rob Galbraith, Nikon says that the sensor is a 36mm x 23.9mm CMOS sensor with 8.45 micron square pixels and a 12 channel, 14bit readout giving at least 9 fps in full readout mode and 11 fps in cropped mode. It is stated that the sensor is an original Nikon design, though it is unknown who actually fabricates it.

From the above, we note a few things. The 12 channel readout is different from the parallel column ADC system used in the IMX021. This is the conventional way of reading out a focal plane array and uses a few high speed analogue to digital converters to quantize the photo-electron signal in each pixel. The 14-bit ADC is interesting, I am not sure whether it truly represents a greater than 12 bit dynamic range or merely a marketing, "keeping up with the Jones'". We can estimate the full-well-capacity at about 55k electrons, similar to the Canon 1DII. The minimum sampling rate at 9fps is 9MHz per ADC. To exceed 12 bit dynamic range (DR), we require a read noise of better than 13.4e which is plausible, though whether this can be achieved at 9MHz is to be seen. The switchable 12/14 bit resolution may indicate that Nikon engineers do not consider the system having greater than 12 bit DR.

The D300 sensor is the most relevant to Sony's plans as on the surface, it looks like the IMX021 (left) recently announced by Sony. The D300 sensor is a Sony-made 12MP APS-C sized CMOS sensor with 5.49 micron square pixels and 14 bit readout at at least 8fps. The IMX021 only specifies 12bit output but at 10fps. It is unknown whether the D300 sensor employs parallel column ADC.

For such a smaller pixel (half the area and presumably FWC), the read noise would have to be half that of the D3 sensor to achieve the same DR. Hence, it is unlikely that the DR exceeds 12 bits, making the 14 bit ADCs superfluous, unless parallel column ADC and multi-sampling have been employed to significantly improve read-noise. A rough estimate gives a 36 multi-sampling with an ADC frequency of 1MHz at 10 fps leading to a reduction in read noise of 6.

It is this latter scenario which is promising for a future Sony DSLR. Though Nikon have a habit of ordering bespoke sensors from Sony (e.g. sensors for the D70s, D2x), the IMX021 seems to be a wholly Sony in-house development, hence the ability to use the parallel column ADC architecture for low noise, high DR imaging may not be proprietary to Nikon.

We will hopefully be able to infer more when Pentax makes its announcements soon, otherwise we will have to wait till Sony make their rumoured announcements early September.

PS A useful introduction to noise sources in CCD imaging is here. Much of the material on signal analysis applies equally well to CMOS sensors.

Sony DSLR Speculations

Update (20/8/2007): Sony have released the details of the IMX021 12.47MP CMOS sensor which will presumably be in the new Sony DSLR. The main features include parallel ADC and 10fps.

My regular camera is a Konica Minolta Dynax 7D, I've had it for 2 1/2 years so far and it's given me stellar service. I was able to use the lenses I bought for the Dynax 7 (and AF 9000) to which I've added one reduced circle lens, the Tamron 17-50mm/2.8 XR di II. For (Konica) Minolta's first DSLR (ignoring the RD-175 and RD-3000, and even the video back for the 9000) of the modern era, it was a great camera, first with in-body anti-shake, more knobs and dials you could poke a stick at, and a nice hefty feel to the body.

However, times have moved on and it's time to upgrade. I think that 6MP is more than enough for 99% of the shots I take, but it's that 1% where higher resolution could come in handy that moves me to want 10MP or more. The AF was a step backwards compared with the Dynax 7, and digital flash has always had the problem of Off-The-Film (OTF) metering incompatibility leading to worse flash performance than in the film days.

So, with Sony having taken over the camera division of Konica Minolta and released the Alpha-100 DSLR last year, many Minolta AF mount (alpha mount) shooters are eagerly awaiting Sony's next move. From all indications, the next camera to be released will be the one on the right, referred to by Sony as an Advanced Amateur Model (hereby to be referred to as the AAM). No details have been released, nothing about the size of the sensor, the resolution, or any other features apart from the inclusion of Super Steady Shot (SSS). So I will dare to make some predictions, and wishes, about what this camera will bring. This is based on the technology developments which have occurred since the 7D was released in 1994 and what should be fitting for the spiritual successor of the 7/700/7000 in the Minolta line.

The heart of a camera is the sensor, whether it be film, a CCD or CMOS. Sony have jumped on the CMOS bandwagon, trying it out on the large sensor R1 previously and stating that it would be transferring its development and production efforts in this direction. CCD technology does have a few theoretical advantages over CMOS in the areas of fill factor, full-well capacity and fixed pattern noise but Canon has shown that practically, CMOS implementations can match or exceed CCD performance in the consumer space. However, some advantages of CMOS are too great to ignore hence Sony's interest in transitioning from CCD. CMOS sensors allow greater integration of image processing functionality into the sensor itself, and it is this functionality which Sony may well want to use to bring DSLRs into the mainstream.

Whenever I hand my 7D to someone else to use, I invariably get asked how do the turn the back screen on in order to frame the shot. I have to explain that they have to look into the viewfinder which leads to much confusion. Integration of Live-View into a large sensor is much more easily achieved in a CMOS chip. Instead of having to clock all the charges out of a CCD in order to rapidly display only a subset, in a CMOS sensor, region of interest (ROI) addressing is easily achieved by random access to each pixel.

Sony recently announced the IMX017CQE 1/1.8" 6MP sensor. What was interesting about this chip is the implementation on a consumer-type device of parallel or column analogue to digital conversion (ADC). Each column of the device has a dedicated readout circuit, hence the charge in each pixel can be measured much more rapidly than in conventional devices. This technology is not new, but so far has been confined to research or low volume high-end devices. It would not be inconceivable that Sony will implement parallel ADC on the new CMOS sensor for the AAM. This is assuming that the technology can overcome some potential hurdles: Cost, more circuitry means larger silicon, lower yield; fixed pattern noise, calibration of each ADC will be essential especially with changes in temperature. With so many ADCs, each one needs to only read out pixels less quickly, hence read-out noise can be much lower. This is due to lower intrinsic noise at lower frequency of operation and also from multi-sampling, where the number of electrons in each pixel is samples many times and averaged, leading to a reduction in the random noise by a factor of the square root of the number of samples. It should be quite possible to reduce the equivalent read-out noise to single electron figures by this method and still retain high frame rates. This would result in very high signal to noise and good low light performance. Video also becomes a viable option for DSLRs, though whether it would be a useful feature is to be seen.

Recently, Kodak announced a "new" Bayer pattern array which mixed clear or "white" pixels with green, red and blue pixels primarily to increase the sensitivity of a sensor. This was touted as a revolutionary development, but in fact is merely one permutation out of many possible Bayer patterns, many of which have been proposed and tried before. For maximum sensitivity, a monochrome sensor would be optimum, however there would be no chroma information recoverable. At the other extreme, the traditional Bayer RGBG pattern gives reasonably good chroma resolution. In between these two points, a continuum of possibilities balance sensitivity versus chroma resolution. One pattern implemented has been the use of complementary filters, Cyan (Green and Blue) Magenta (Red and Blue) Yellow (Green and Blue). An alternative would be to use White (R+G+B) Cyan and Yellow in a CWYW pattern. This would be equivalent to a RGB pattern in terms of chroma resolution, but would have an average photo-electron absorption of 5/6ths compared to 2/6=1/3 of an RGB array, or 2 1/2 times greater sensitivity. In terms of colour accuracy, the CWYW pattern may be more sensitive to noise so this would have to addressed in the de-mosaicing process.

Flash performance on DSLRs has been problematic. This stems from the fact that digital sensors have specular reflection characteristics. OTF metering relies on diffuse reflection from the surface of the film in order to calculate flash exposure. However, the light reflected from the surface of the sensor (of the order of a percent or less due to anti-reflective coatings on the IR filter/anti-aliasing stack) bounces like as from a mirror, which means that the usual flash metering sensors cannot intercept the rays. There are several ways this could be overcome in an all-electronic flash metering system embedded in the sensor. Most sensors incorporate overflow drains, pixels which exceed full well capacity dump their excess electrons into these drains and not into neighbouring pixels. By suitable high speed monitoring of these drains, overexposure could be detected and the flash output cut-off. The overflow regions could be segmented allowing a degree of selective exposure. More sophisticated would be a layered structure, the top surface pixels would be the conventional picture taking elements but below would be larger light sensitive regions which would capture a small fraction of the photons falling onto the sensor. These metering regions could also be used for on-chip continuous metering, useful for mirrorless operation.

With the use of Live-View, contrast AF becomes feasible. This could be used in conjunction with phase-difference AF as a Minolta patent shows. Phase-AF would provide coarse AF after which the mirror flips up and then contrast AF fine tunes the focus. I can imagine several permutations being available depending on the shooting situation. Sony may also implement an electronic shutter (like Kodak's CMOS Global Shutter). This would also mean far higher flash-sync speeds.

Another Minolta patent may show a future development, though it is not likely in the near future. This being the integration of in-lens image stabilisation with the current in-body SSS. This would combine the advantages of both systems, long lens performance of the in-lens system, and universal performance (especially wide aperture short focal lengths) of the in-body system.

The above are the more revolutionary aspects of the camera I envisage Sony releasing shortly. More mundane features I would like are: interchangeable viewfinders screens, type M/ML in particular; intervalometer; focus distance display; custom metering programs; a real mirror lock-up (MLU) as well as the 2s option; 1/2 pixel shift using SSS; Bluetooth GPS compatibility; good ergonomics.

My specifications/wishlist for the Sony AAM:

• 24mm x 16 mm (approx.) 12MP CMOS Bayer Array (White,Cyan,White,Yellow this is pure speculation)


• 5.5 micrometer pixel with 50,000 e- FWC


• Parallel ADC readout, 10e- equivalent noise in normal mode, 5e- in "slowscan" mode


• Pentaprism 95% coverage viewfinder, x0.85 magnification. Interchangeable screens including Type M/ML (for manual focussing/gridlines)


• 9 AF sensors (distributed wider than on the 7D). Centre X and + type, outer + type


• Imaging AE in pentaprism, colour sensitive


• Live-View, real-time histogram and metering


• 4 fps with conventional mirror flip up, 10fps with live-view


• 30s to 1/8000th shutter (mechanical) or 1/16000 (electronic)


• On chip flash metering system. Flash sync to 1/16000


• Wireless flash control, compatible with 5600HS/3600HS


• Red focus assist lamp


• Super Steady Shot with improved low frequency drift


• Focus distance display on rear LCD


• Dual CF and SD card slots


• Compressed RAW format/DNG


• Bluetooth connectivity for GPS, file tagging, camera control

For David Kilpatrick's take on things, look here.

D-Wave to Wave Goodbye?

D-Wave just recently "demonstrated" their 16 qubit prototype at the Computer History Museum. It has understandably garnered quite a lot of press, particularly amongst the geekier elements of the World Wide Wibble. From what I've read, they are trying to build an adiabatic quantum computer from superconducting qubits (Josephson junctions). Other quantum information scientists have commented on the plausibility of the device actually working, some more optimistic than others. I would class the general plausibility as just above Steorn, but I will reserve final judgement for if or when they actually release technical details, like temperature, energy gaps, decoherence rates, speed of operation, charge fluctuator noise levels and algorithms run. If they do actually manage to build a 1024 qubit device which is controllable by 2008 (and I don't mean just a bunch of SQUIDs connected to each other), then I will be very, very, very surprised.

I hope that the whole media circus surrounding the company and its claims will not seriously damage quantum information and computation in general. Inevitably, when commercialism meets science, science usually takes a back seat to publicity and PR.

Quantum Sock Theory

I wrote this piece up for Quantiki, thought it may be good to share here (especially considering the glacial pace of my posting history):

Quantum Sock Theory

The advent of mechanised means of cleaning clothes brought new challenges and exposed new phenomena unexplainable by the old manual theory of laundry. In particular, the discovery of spontaneous sock disappearance was totally contrary to the principles of pair production. A new theory of laundry was required, one that took into account quantisation of the textilo-clothic field, whose quantised carriers are called lint. Not only did the new theory correctly predict the spectral distribution of coloured lint on a black garment, but also the phenomenon of tunneling, the disappearance of socks from a nominally closed laundry system being one of the more startling consequences.

Socks obey Hoson article statistics which apply to indistiguishable articles of clothing such as a pair of socks. Socks do not like to be in the same state, even the same country, let alone the same washing machine. When brought into violent collision within the agitation cycle, and the spin cycle in particular, the inter-sock potential can reach such high levels leading to an interdimensional tear in the fabric of spacetime. How this actually occurs is still uncertain, requiring a deeper theory which can take into account the discontinuous nature of fabric at the Pluck length. The leading, or most vocal, candidate for such an ultimate explanation is called Thread Theory.

Sock Chromo Dynamics (SCD) is a development of the basic theory to take into account another property of socks, which Sockocists whimsically have called colour. However, it seems that, unlike spin or charge, colour is not a conserved quantity, especially in the presence of bleach. It has also been posited that a phenomenon call mixing can also occur. Observed is also the related phenomena of Fashion Violations, such as the wearing of different coloured socks, but this is usually only observed in Universities, especially Maths, Engineering and Physics departments.

Sockocists are eagerly waiting for the completion of the LHC (Large Hosiery Collider) which will be able to explore the collision of heavier or larger articles, such as stockings, pantyhose and tights. Vigorous tumbling of these larger articles may lead to insights into the elegant, but yet unproven, Twisted Theory and even the more abstract Knotted Theory.

Two Talks

Yesterday (Wednesday 4th October), I went to two contrasting talks. The first was by Harry Collins, of whom I have already said something about in my previous post, speaking at the University of Glasgow Physics Colloquium. The second was by David Reid, the director of the Glasgow Homeopathic Hospital, speaking at the Glasgow Philosophical Society.

The talk by Collins briefly recapped his research into "Interactional Expertise", but the main body of his talk was devoted to the notion that you can be a physicist without maths. He goes so far as to advocating specific physics courses with no mathematics, to train physics-savvy grads for managerial roles in society. Now, if one looks at the spectrum of mathematical ability within the physics community, it varies by quite alot, from mathematical geniuses, like Witten, to the less adept (but perfectly satisfactory physicists) usually to be found in the laboratory:-). Just because not all physicists are at the former end of the spectrum (and I would count myself firmly in the middle of the pack, or even below due to atrophy), it would be wrong to conclude that simply the existence of mathematically less capable physicists means that it is desirable to try to teach physics without maths. Usually, great physicists (Collins presents Bohr and Drever as examples, which may be arguable) who aren't great mathematically succeed despite their mathematical failing, usually compensated by a formidable intuitive grasp of the physics. However, these people lie way outside the norm (for physicists) and they are the exception which proves the rule. One may argue that traditional physics courses are predicated on the assumption that students be mathematical, so it is not surprsing that physicists have in general greater mathematical ability than the general populace, hence the mere fact that physicists have mathematical ability (to greater of lesser degree) does not in itself show that you need maths to be a physicist. But I'd argue that what separates physics as a science from merely a collection of facts about the universe is that mathematical models give concrete form to theory, and without being able to grasp the language in which the models are described, one cannot really be called a physicist. Besides which, trying to teach physics without maths is a like doing a marathon walking on your hands, in principle doable, but ultimately fruitless.

The other talk was a different kettle of fish. I wasn't quite sure exactly what Reid was tring to say. Most charatibly, he is imploring a more humane, kind and individually tailored approach to patient care, or basically better bedside manner. I have no objections to this sentiment. Less charitably, he could thought to argue that a doctor should be concerned mostly with making a patient "feel" well, rather than concentrate on the notion of "disease". There certainly is some scientific evidence that psychological factors are important in physiological response to illness and treatment. However, one should balance the relative magnitude of this effect with respect to other physical factors. There are philosophical questions raised by this approach. We should bound ourselves in nutshells and count ourselves kings of infinite space. If we perceived ourselves as well or bettter, then the actual reality is not important.

Reid was quick to duck any questions on Homeopathy, preferring to concentrate his talk on his vision of Integrative Healthcare, where doctors are melded with the role of welfare officers and crisis talklines. Sprinkled throughout were potshots (via cartoons) at NHS managers and drug companies, easy targets especially since the majority of the audience seemed to be quite sympathetic.

I think underlying the current rise in Complementary and Alternative Medicine (CAM) is the unrealistic expectations people have about medicine, a victim of its own success one may say. "Shit Happens" and when fate deals out a losing hand, people feel cheated by conventional medicine and seek alternative treatments to fill their hopes.

There are parallels between the fight against quack medicine and pseudo-science. Both stem from a mis-understanding of what science actually is and what its limits are. People prefer certainty, but if Science and Modern Medicine cannot provide that, they will seek out other forms of assurance. That's not to say that modern conventional medicine doesn't have its own failings, but the inability to "cure" the incurable isn't one of them, just like the inability of science to provide "truth". I cannot see a quick fix to this problem, apart from making everyone pass a basic course in philosophy (of science) and critical thinking.

Interactional Expertise (Blagging Your Way in Academia)

A story which appeared in Nature a few months ago has tickled my ribs. Basically, a sociologist of science hung out with Gravity Wave physicists for a 30 years and picked up enough of the lingo that his responses to seven questions on gravitational wave physics was indistinguishable from answers from real gravity wave physicists. Some have called it a reverse-Sokal hoax. The sociologists involved in the experiment have likened it to a Turing test. I find that the findings of the experiment resonate with my experiences as a research scientist with fingers in half-a-dozen pies (like geometric phase, quantum channels, cryptography, quantum dots, ion traps, and control theory). My interactions with specialists in several fields are very like those of the sociologist and the GW physicists, trying to pass myself off as someone conversant with the specialist terminology and concepts. I find myself now doubting my own competence as a physicist, maybe I've just blagged my way to where I am?

One may try to use the results of the sociology experiment (Is this ironic, to use the techniques and methodology of the subject under study?) to reinforce the claim that all of science is simply social construction, that scientific truths have no greater claim to validity that any other socially conventions, and other notions of linguistic hegomonies. However, we need to look at the actual study and how it fits in with the wider framework of their sociological research. They distinguish between different grades of expertise and in particular, the sociologists do not claim to have imitated "contributory expertise", the ability to do research, merely the ability to appear to speak as if one had the ability.

I myself am philosophically in the functionalist camp. If someone does all of the things that a gravitational wave physicist does, then functionally they are a gravitational wave physicist. A full Turing test would probe the full technical competence of the subject. As it stood, the questions asked in the test were conceptual rather than technical or claculational so did not probe all of the functional aspects of being a gravity wave physicist. A movie set of submarine may look like a sub but can't submerge. I am reminded of the great mathematician, Ramanujan, who exemplified the total opposite of interactional expertise. He was totally self-taught, not even having talked to another professional mathematician before he was brought to Cambridge by Hardy, yet even today his results are still filtering into mainstream mathematics.

You can't spend 30 years with gravity wave physicists and not pick up some of the physics. The important part of the responses were that they were technically correct. Even though the sociologist couldn't do calculations in linearized general relativity, he had absorbed enough physics to answer the questions correctly. This is what happens when you go slightly out of your speciality, you may not be able to be perfectly conversant with the theoretical techniques but may know enough to understand the general concepts involved. But a thorough scientific training should allow one to bootstrap what one already knows to learn the new field. I greatly admire S. Chandresekhar who changed his specialism six times in his career, writing monographs on each field at the conclusion of each episode.

So what? Science, contrary to what some radical cultural relativists would say, is not about making up stories about the world and merely talking in the right terminology and giving the expected answers demanded by a imperialistic and fascist orthodoxy, but is about doing, probing nature and contributing to a tightly constrained framework of observation, experiment and theory.

Not Even Wrong?

I've recently read this book by Peter Woit and can recommend it as an (partial) evaluation of the String Theory programme. Woit's argument is that String Theory has not lived up to the hype of its greatest proponents and that 20 years of continued work have not lead to the breakthroughs which would warrant the dominant position it has in high energy and gravitational physics departments.

A String Theorist, with whom I spoke about the book, was quick to affirm that he himself did not think strings were going to be the fundamental theory, but rather the techniques developed by string theory has actually be useful for conventional QCD. So even if the strong claims, by a minority of String Theorists it was stressed, were mostly hype, he reiterated the argument, "It's the only game in town". Whether this is a compelling argument is not clear to me but Lee Smolin, who has worked in String Theory, would disagree, citing several different approaches to unification in his book which also is critical of the present domination of the String Theory.

I think it's an exciting time to be a physicist despite the apparent stagnation of fundamental particle physics. We are only beginning to plumb the depths of complexity of many-body physics. Quantum computation and information is an example of where whole avenues of phenomena were waiting to be discovered, despite all the work on quantum theory and the foundation of its mathematical principles. Though it's not inventing "new" physics, we are discovering surprising things about the connections between established sub-fields of science. Looking further out, new astronomical observations are raising more questions than they answer, dark matter, the cosmological constant, gamma ray bursts etc. The opportunity to discover important insights is not simply confined to String/M/Brane Theory.

Perpetual Dreams

Yet another claim of free energy, this time due to magnets. And yet again, the media report these claims without critical examination. Of course it isn't the job a newspaper to analyse the scientific aspects in great depth, but a bit of meta-analysis may have been useful to apply to all such non-mainstream claims (from the Guardian article):

And they are so confident that they have thrown down the gauntlet to the scientific community in a bid to prove that they have rewritten the laws of physics. Last week, frustrated that they couldn't persuade scientists to take their work seriously, McCarthy, Walshe and the other 28 shareholders of Steorn, a privately owned technology research company, took out a full-page advertisement in the Economist. In it, they called upon scientists to form a 12-member jury to decide whether their free-energy system is real, hoaxed, imagined or incorrectly well-intentioned.

The problem is that extraordinary claims require extraordinary evidence, and that the burden of proof in such a case is really on the side of those making such claims. When modern physics, within its long-established borders, has been so successful and consistent, coming up with a perpetual motion machine would seem to be extremely unlikely.

According to McCarthy and Walshe, the marketing manager, there have been no fewer than eight independent validations of their work conducted by electrical engineers and academics "with multiple PhDs" from world-class universities.

The fact that conventional physics is so successful and consistent, any credible evidence that the inventors' claims were true would have any true physicist to drop everything they were working on, and instantly switch to studying such a violation of all known laws of physics. They are claiming up to 4 times as much (mechanical) energy as they are putting in. A signature of free energy this large would be absolutely unmissable. Why haven't we seen anything run? They need only hook up one of their devices via a generator to the electricity grid and start making money.

Of course, the whole affair is running along the usual lines for a fringe claim. Conventionally, if a scientist makes a great discovery, after filing the necessary patents of course, they will disclose the set-up and techniques required to reproduce those results by independent researchers. If others are able to reproduce the results or confirm the observations, then one can have more confidence in the validity of the original claims. However, the inventors of this latest affair are, "seeking a jury of twelve qualified experimental physicists to define the tests required, the test centres to be used, monitor the analysis and then publish the results." This strike me as very odd. Science is not about testing black boxes. Without access to the inside of the black box and an attempt to understand its properties, the whole thing looks especially dubious. Why are their white papers restricted to registered academic users of their web-site and potential jurists? Why not post them on the arXiv like every other working physicist? The papers, here and here, claiming an anti-gravity effect above rotating High Tc superconducting discs were posted there (not that I find these claims credible either).

Even the Pons and Fleischmann affair was conducted slightly more openly. Other researchers tried to reproduce the experimental set-up but failed to obtain convincing data. Even then, the manner in which th original "results" were announced, the supposed signatures of fusion, and the ultimate lack of firm confirmation by anyone else has lead to cold fusion dying away. The supposed mechanism of cold fusion was at the extreme boundary of known physics, ultimately beyond it, but at least it was not totally inconsistent with what we know (just a extremely inconsistent).

It isn't up to the physics community to take up any "challenge", the challenge is for the inventors to back up their claims with proper disclosure for a truly scientific evaluation. Until that is done, the whole business cannot be taken seriously.