Hollow Man

Ok so, so far I’ve been talking about seeing what is normally hidden without actually touching, removing or breaking anything. But what’s the state of affairs at the other side of this spectrum? Invisibility.

Camouflage is a universal trait of any living thing thing out there and humans have always been preoccupied with its developpement, from using the fur from other animals to stealth bombers. The ultimate camouflage would ofcourse be pure invisibility, so yeah, how close are we to getting an invisibility cloack?

I found this old TEDInvisible-Man-SFX talk from 2013, which you can watch here if you wish: TED talk video. I’ll give you the quick rundown tough:

Basically it mentions that H.G. Wells wasn’t that far off with his theory in the book “The Invisible Man”.  The talk might disappoint you however, no true visual invisibility is achieved. The theory they propose does have some interesting arguments though. “Meta-materials” that provide a negative refraction index.

A short refresher:
Refraction is the principle of different materials bending light in different ways, normally the refraction number is positive, measured against a complete vacuum as a reference. (Which has a refraction number of 1, air has 1.000293.) The most famous example to illustrate this phenomena is a straw in a glass of water, seeming oddly ‘broken’ and shifted as shown on the left in the image below. Negative refraction would result in the even more distorted straw deformation seen in the glass on the right.
negative_refraction-640x369In theory the property of negative refraction should allow you to bend light in the opposite direction to which you’d normally expect it to go, essentially opening the door to invisibility. If you really want to go deeper into the physics of it I can start you off with these Wikipedia articles on the topic: http://en.wikipedia.org/wiki/Negative_refraction and http://en.wikipedia.org/wiki/Snell%27s_law.

For now the guys from the TED talk haven’t been able to apply it to visible light, but they have been successful in the domain of radio waves.  Applying these materials as a cover could be used to make radio towers (like the ones for your mobile phone) invisible to each other, dramatically reducing mutual interference. The meta-material allows electromagnetic waves to be emitted from within but makes incoming radio waves just ‘pass trough’ the antenna.

This again shows how messing  around with a certain technology or theory can result in major advances in other areas of technology than intended.

The only thing close to an actual invisibility cloak i could find on the net make use of complicated suits, using camera’s  strapped to the back and either LCD/ LED technology ‘clothing’ or using a projector placed in front of the subject. The entire setup is hardly subtle and is very far away from providing true invisibility of any sorts in my opinion.

In short: invisibility cloaks, on our way but far from actually getting there.

So, there’s an evident ethical question to be posed here, do we really want invisibility cloaks to ever be a thing? It didn’t end well for the protagonist in Well’s book, but i won’t ruin the plot for you. Harry potter might have only used his invisibility cloak for doing good in the scenes that were shown to us, but what about all those other times we weren’t told about?!

So, do you personally see more advantages than disadvantages in this technology or do you think this is just another thing that just shouldn’t ever be a thing? Also, where do you think it could actually be handy?

I think this research should just continue, i can see many benefits but I’m going deeper into that in a future blog.
I’d get very paranoid however. But in the end aren’t we all already walking around with devices that could, in principle, listen to everything we hear, say and see ourselves to some extent? I don’t think covering an invisible person with a post-it would do that much.

As a personal extra: what use of invisibility in fiction is your favorite? Mine was in the movie ‘Hollow Man’ also shows the concept of invisibility,if you haven’t seen it, I recommend it as an entertaining watch !

Innovations in x-ray technology

Röntgen rays were discovered over 100 years ago, and yet, even now, improvements on its application are still being made.

I’ve read an interesting article about a new technique researched by the NIST (National Institute of Standards and Technology) to improve measurements of x-rays by reducing the error on the measurements.

Almost every material has its own, unique energy signature. This makes it possible for the police to distinguish between different materials in suitcases (as mentioned in my previous post). But to measure this “signature” accurate measurement of angles is of utmost importance. each material actually absorbs some of the wave, but reflects the rest, and it’s by measuring the angle at which the waves are reflected, scientists can determine what material it is they are scanning.

Using the new technique, the first major improvement since the 1970’s, it’s possible to measure the angles with an uncertainty of only 0,06 arcseconds or as the author of the article said

If a giant windshield wiper stretched from Washington D.C. to New York City (364 kilometers) and were to sweep out the angle of one of these errors, its tip would move less than the width of a DVD

To me, this is very hard to imagine something that precise, but I’m amazed at what accuracy can be achieved and I hope this new method will make a lot of new techniques possible or improve detection methods as used in  several areas of science such as astronomy, physics, chemistry,…

For those who want to read more about this, with a more detailed explanation of the old and new technique, the article can be found in the link below


What’s really inside?

At airports around the world, the question “What’s inside that bag?” is answered thousands of times a day, to detect explosives, poison, chemical compounds,… in both carry on and checked in luggage.

Checking all those bags, trolleys and suitcases by hand would be too much work and might also be dangerous, so thank god for CT-scanners.

Using x-rays, it’s possible to see the content of the bags without opening them and thanks to some smart technology, it’s even possible to distinguish a difference between organic, inorganic or metal objects because of a difference in density and amount of radiation the objects absorb.

Most bombs are made from organic material, but most organic objects are low-energy, so for this reason, the rays from the scanner are passed through 2 detectors: first through a full detector, then through a high-pass filter to filter out the low energy signatures and then through the second filter. The software automatically compares the data from both detectors and the differences between them are the low energy objects, most often the organic material.


I’m sure most of us have heard stories about camera’s not working after passing through a scanner at the airport, laptops that stop functioning,…
These are however myths if those objects are in the carry on luggage. The scanners used at the security checkpoints are what they call “film-safe”. The amount of radiation is so low there will be no effect what so ever on film or electronic devices.

If however you put your camera in you checked bag, there is the possibility of damage. The checked luggage is often processed in larger batches, with more powerful equipment, higher levels of radiation and so more effect on the film. Laptops and other electronic devices should however be safe with the latest technology.

This is once again a great way NDT makes our lives easier. It is however interesting to note that this isn’t the best bomb detection method available. Most airports still have a dedicated staff of trained dogs to sniff out suspicious items, often with a higher success ratio than modern technology research has found.

No matter how good technology is, nature still does it better.

For more information about how the scanners at airports work and what other methods are used check out this link

Getting up the mountain safely

Some of you were probably skiing a few weeks ago. Hopefully nothing bad happened like the cables of the skilift failing.

Those cables are actually rather prone to failure but luckily the cables are designed to withstand a lot and there are easy methods to check the cables and replace them if necessary, before any real dangerous situations occur.

First lets go over the different ways the cables can fail. The most obvious one is of course broken wires, which happens rather frequently, but because the rope actually is made from several smaller ropes twisted together as you can see in figure 1

broken rope element
Figure 1: Rope with broken wires

Other possibilities include but are not limited to:  birdcage (the outer layers of the rope becoming longer than the inner ones, as seen in figure 2), loose wires, loop formations, nodes which can be seen in figure 3 and many others Continue reading Getting up the mountain safely

Imaging systems and your privacy.

Part 2: Seeing your thoughts.

Upon researching the previous privacy blog i stumbled upon some other stuff too.

For instance, have you at any point ever wondered why that police helicopter just kept going in circles above your neighborhood? Well, as it turns out they found out a rather clever trick to discover possible illegal  marijuana plantations.

Using heat camera’s they scan entire neighborhoods for unusual heat signatures, weed plantations are easy to spot as they usually clearly stand out on the special footage.

article-2461412-18C0914600000578-186_634x356Or as in the picture on the left, the plantation in this flat was just literally glowing with an absurd amount heat. (Corresponding article here.)

It’s another method to see whats going on inside people’s private property. But unlike the technology used in the first blog I personally don’t feel this one really invades privacy as it doesn’t pierce trough the surface of your home… What’s your opinion on this method?

On a way different level they are experimenting with stuff you can only dream of:
Looking into someone’s brain !

In the following Youtube clip researchers show video fragments to  test subjects while extracting brain activity data using fMRI. Subsequently they use this data to re-create the original footage by matching the original data with a huge database of random video’s (youtube clips). Sort of like how you can now use Google images by uploading a picture yourself and getting the same or similar pictures as a search result.

The footage in the red square is the original, shown to the test subject.
The footage in the green squares is the reconstructed video (3 different iterations are shown), which is composed by averaging out the video’s from the blue squares, which are possible matches.

Obviously the resulting  footage is currently relatively raw and inaccurate. The Youtube video above stems from 2011, but if you look at a video from only a year prior, you can see they have made huge advancements already.

If they ever get this right, they might be able to ‘fully’ visualize a persons thoughts and dreams.

So obviously this technology can go many ways. Both bad and good, obviously by the title of this blog i’m hinting towards possible privacy abuse when used against someones will. But it’s easy to see it has many possible positive applications too.

What do you see for the future of this technique? If it reaches it’s full potential, and provides a pretty clear image, will it mostly be used for evil or good?

Say now for instance, should the law be allowed to use this on key witnesses ?
Could it be used as a lie detector on inmates? What in the case of people who ended up in a coma or vegetative state.
Should the family be allowed to hook them up on such a machine, just to see what’s still going on in there?

I know it’s very hypothetical  and personal, it also covers a fairly ‘general’ side of privacy, but I’d still like your opinion…

Read the abstract and full text of the related research paper here: