The idea of invisibility has been around in mythology and fiction for thousands of years but the Harry Potter books and
Invisibility Cloak in Action (Photo Credit: Warner Bros.)
movies brought the idea of an Invisibility Cloak into the public eye. Everyone has thought at some point about what possibilities being able to make themselves invisible would present. But invisibility is only the stuff of fiction.. right?
Well, right now researchers haven’t quite got to the level of Harry’s cloak but they’re certainly getting there. There are many different approaches that are being taken towards this technology and I’m going to give an insight into a few of them.
The first and currently most effective technology is called optical camouflage technology. This involves a camera filming what is behind an object and this image is then projected onto the front of the object, in effect allowing you to see ‘through’ the object. This is similar to blue screen technology used in Hollywood but in this instance what you are wearing acts as the blue screen rather than you standing in front of one. It is just like the technology seen on James Bond’s Aston Martin in the movie Die Another Day.
Researchers at the University of Tokyo are leading this field and have created an ‘Invisibility Coat’ that resembles a rain jacket but is made out of retro-reflective material (that reflects and refracts the light back at the source) . It is made from 50 micron beads that are lined up and tightly packed together. Because the beads are so small, you can still project an image onto it regardless of how it is wrinkled. There are many potential uses for the technology such as using it in car interiors to eliminate blind spots and be able to see right ‘through’ to the surroundings.
Adaptiv technology, created by BAE systems is designed to conceal military vehicles. It allows the vehicles to mimic the temperature outline of it’s surroundings. This can make the vehicle invisible to both night vision systems that see infrared light and heat seeking systems which is clearly a major advantage on a battlefield. The technology works by projecting temperatures onto the special outer layer of the tank. A database of recognizable outlines has been created and a tank can be made to look like anything from a cow to a truck when seen through an infrared camera. Researchers are now working on making this technology work in other wavelengths, especially visible light, so as to create ‘true’ invisibility. BAE estimate that the Adaptiv technology could go into production within 2 years. Further reading and video can be found here.
Finally, the technology that is most likely to be able to create the effect of Harry’s invisibility cloak are ‘meta-materials’ with negative refractive indexes that are being worked on by many researchers. Meta-materials have the ability to manipulate light and can in effect bend light around them. Last November Scientists managed to create flexible meta-materials that bent visible light for the first time. Currently they can only be made on a small scale but this was a huge step forward. Interestingly these meta-materials may also be used to create lenses that “can zoom to the micron level, making it possible to spot germs, chemical agents and even DNA, using basically a pair of binoculars.”
30 years after the first reported cases of AIDS we still do not have a cure for a disease that has killed 25 million people.
Source: Wikipedia
The World Health Organization currently estimates at least 33 million people are currently infected worldwide and approximately 2 million deaths are attributed to the disease each year. While in most western countries the impact of HIV is limited due to the use of Antiretroviral drugs with HIV+ patients sometimes having life expectancies close to the average uninfected individual. However in less affluent countries AIDS is a serious problem.
Now to explain how HIV/AIDS infects an individual and how the current treatments work. The HIV virus replicates in the human body by inserting it’s genetic code into human cells, most commonly a type called CD4 cells, which then produce a large amount of HIV particles before dying soon afterwards. Antiretroviral drugs interfere with this replication process of the HIV virus in the human body and reduce the amount of HIV to extremely low levels (so low that sometimes the presence of HIV can’t even be detected by a standard test). However a problem lies with ‘resting’ CD4 cells that can lie dormant for years and keep HIV’s genetic material in the body. Then when the patient stops receiving the treatment the “HIV can re-establish itself by leaking out of these “viral resevoirs”” (avert.org). So there is 2 potential paths for HIV cures:
A Sterilising Cure – A cure that would remove all infected cells.
A Functional Cure – A cure that will keep the virus dormant and prevent it from replicating after the discontinuation of antiretroviral drug treatment. (Further reading on potential functional cure)
AIDS related discoveries have been in the news regularly in recent months. The first of these stories was published in the journal Nature Structural and Molecular Biology and acknowledged an unprecented number of people as helping to make the discovery. Scientists had been trying to work out the structure of “M-PMV retroviral protease – an enzyme that plays a key role in the development of a virus similar to HIV” (http://www.bbc.co.uk/news/technology-14986013), for over a decade without success. Amazingly when the protein was given to players of an online game called Foldit it only took 10 days for the 57,000 players (that were acknowledged in the paper) to work out the lowest energy configuration of the protein. “This result could be an important step forwards in the development of anti-Aids drugs”. MSNBC Video on Foldit Discovery
Source: dailymail.co.uk
Another recent lead in the hunt for a cure is the discovery that removing cholesterol from the membrane of HIV can stop it from damaging the immune system. Cholesterol is necessary to keep the outer membrane fluid and the virus picks it up from the first immune cells it infects. When the cholesterol is removed, HIV can no longer communicate and disrupt the immune system. These findings were published in journal Blood and scientists are now working on seeing if they can turn the inactivated virus (that no longer contains cholesterol) into a vaccine. (Further reading on cholesterol discovery)
A third paper published recently in the journals Vaccine and Journal of Virology by researchers in Spain details a new vaccine called MVA-B that has demonstrated promising results. The vaccine is “made with bits of non-infectious HIV genetic material and is designed to train the body’s immune system over time to detect and fight different components of the virus”. The vaccine has been tested on healthy volunteers (without HIV infection) and achieved an immunological response against HIV in 92% with 85% of them maintaining immunity for 12 months. The next stage is to test the vaccine on HIV positive individuals and if these trials go well “the scientists believe they may well have found a vaccine that could turn HIV into a minor chronic infection, similar to Herpes” and would therefore only be a problem for people with compromised immune systems. (Articles for further reading on MVA-B vaccine here and here)
With these recent discoveries this elusive cure may not be far away and it is exciting to think that we may live to see major diseases cured in the very near future.
Cross-section of the CNGS experiment through the Earth.
On the 23rd of September 160 scientists from the OPERA experiment published a paper online suggesting they have found evidence of neutrinos travelling faster than the speed of light. This announcement has thrown neutrinos and the potential implications of the finding with relation to Einsteins Theory of Relativity into the scientific spotlight.
First of all to provide a little background to the study, neutrinos are tiny subatomic particles each with a “mass of less than a millionth the mass of an electron”. They are uncharged, hence the name neutrino coming from the word neutral, and hardly react with other matter which allows them to pass right through the Earth. Most neutrinos we know of are radiated by our Sun, with 65 billion neutrinos passing through every square centimeter of the Earth perpendicular to the Suns rays every second. They are also hit the Earth from other cosmic rays and are produced as a product of radioactive decay. Scientists can create neutrinos in particle accelerators like the one at the CERN research facility in Geneva, Switzerland (home of the Large Hadron Collider) shown below.
Artistic view of the underground layout of CERN and the SPS (Super Proton Synchrotron)
The CNGS (CERN Neutrinos to Gran Sasso) experiment’s main focus is to investigate the phenomenon of how neutrinos ‘oscillate’ (change between the 3 types or flavours of neutrinos (electron, muon and tau neutrinos)) as they travel long distances through matter. Determining the velocity of neutrinos is a secondary aim of the experiment (however after these findings I’m sure it moved up the list of priorities). Muon neutrinos are created in the Super Proton Syncrotron (SPS) particle accelerator at CERN and fired 732km through the Earth to the OPERA (Oscillation Project with Emulsion-tRacking Apparatus) detector in Gran Sasso, Italy. The speed of these neutrinos is calculated using the same basic physics of Speed = Distance / Time that you learned in high school, however with more precision than ever before. The distance between the SPS in Switzerland and the OPERA detector in Italy is known to within 20cm and the timing is measured using GPS timing signals and a cesium atomic clock with the sensitivity of this experiment “roughly an order of magnitude better than previous experiments.” This experimental design is shown below.
Cross Section of the CNGS Experiment through the Earth
Neutrinos are notoriously hard to detect due to their neglible mass but after 3 years the OPERA experiment has managed to collect 16,000 neutrinos (only 10^-14 % of the neutrinos created!) with some very interesting findings. When comparing the time it took the neutrinos to make the trip to Gran Sasso to how long it would take light, they were shocked to find the neutrinos “arrived at Gran Sasso sixty billionths of a second earlier, with an error margin of plus or minus 10 billionths of a second”. This has led them to publish their findings for the wider scientific community to scrutinise.
This paper has pushed physics into the media spotlight due to the implications this finding could have if it is replicated. If it is proven that the neutrinos are in fact travelling faster than the speed of light (rather than this being the result of some experimental error or statistical miscalculation) then they are breaking one of the fundamental laws of modern physics – that nothing can exceed the speed that light travels at in a vacuum (effectively the speed limit of the universe). This is the foundation of Einsteins Theory of Relativity and a cornerstone of the maths we use to understand and model the universe. Brian Cox, a professor of particle physics at the University of Manchester said, “If you’ve got something travelling faster than light, then it’s the most profound discovery of the last 100 years or more in physics. It’s a very, very big deal. It requires a complete rewriting of our understanding of the universe.”
If neutrinos do in fact travel faster than light then this “raises the troubling possibility of a way to send information back in time, blurring the line between past and present and wreaking havoc with the fundamental principle of cause and effect.” Another explanation being proposed is that the neutrinos are skipping through another dimension on their way to Gran Sasso which also raises a lot of fascinating questions.
However the media should be prepared to wait a long time before this is proven/disproven because theres an important paragraph in the paper published by the OPERA team that hasn’t recieved as much attention (or the media has chosen to ignore).
“Despite the large significance of the measurement reported here and the stability of the analysis, the potential great impact of the results motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly. We deliberately do not attempt any theoretical or phenomenological interpretation of the results.”
I find this very interesting because it shows how the team of scientists are not reading too much into their own results, at least for now and are cautious of making a revelationary claim that could be disproven. “They do not claim that the neutrinos are actually exceeding the speed of light, only that the measurements to date show something unexpected [and they] are reaching out to the high-energy physics community to improve the experiment and data analysis.” Therefore despite the enthusiasm of the world’s media, the scientists lack of belief suggests we shouldn’t rush to get too excited or too worried about the consequences of this finding until other scientists such as those working on the T2K experiment in Japan have replicated their results.
However, one thing’s for sure, it’s definitely an intriguing time for the physics community.
