Testing relativity in the lab

Jul 20, 2009
Through the optical-mechanical analogy, metamaterials and other advanced optical materials can be used to study such celestial phenomena as black holes, strange attractors and gravitational lenses. Here an air-GaInAsP metamaterial mimics a photon-sphere, one of the key black hole phenomena in its interactions with light. Credit: Xiang Zhang

Even Albert Einstein might have been impressed. His theory of general relativity, which describes how the gravity of a massive object, such as a star, can curve space and time, has been successfully used to predict such astronomical observations as the bending of starlight by the sun, small shifts in the orbit of the planet Mercury and the phenomenon known as gravitational lensing. Now, however, it may soon be possible to study the effects of general relativity in bench-top laboratory experiments.

Xiang Zhang, a faculty scientist with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and professor at the University of California Berkeley, lead a study in which it was determined that the interactions of light and matter with spacetime, as predicted by general relativity, can be studied using the new breed of artificial optical materials that feature extraordinary abilities to bend light and other forms of .

"We propose a link between the newly emerged field of artificial optical materials to that of celestial mechanics, thus opening a new possibility to investigate astronomical phenomena in a table-top laboratory setting," says Zhang. "We have introduced a new class of specially designed optical media that can mimic the periodic, quasi-periodic and chaotic motions observed in celestial objects that have been subjected to complex gravitational fields."

A paper describing this work is now available on-line in the journal . The paper is titled: "Mimicking Celestial Mechanics in Metamaterials." Co-authoring it with Zhang were his post-doctoral students Dentcho Genov and Shuang Zhang.

Xiang Zhang has been one of the pioneers in the creation of artificial optical materials and their applications to such phenomena as negative refraction, electromagnetic invisibility devices and microscopy with super-resolution. Credit: photo by Roy Kaltschmidt, Berkeley Lab Public Affairs

Zhang, a principal investigator with Berkeley Lab's Materials Sciences Division and director of UC Berkeley's Nano-scale Science and Engineering Center, has been one of the pioneers in the creation of artificial optical materials. Last year, he and his research group made headlines when they fashioned unique metamaterials - composites of metals and dielectrics - that were able to bend light backwards, a property known as a negative refraction that is unprecedented in nature. More recently, he and his group fashioned a "carpet cloak" from nanostructured silicon that concealed the presence of objects placed under it from optical detection. These efforts not only suggested that true invisibility materials are within reach, Zhang said, but also represented a major step towards transformation optics that would "open the door to manipulating light at will."

Now he and his research group have demonstrated that a new class of metamaterials called "continuous-index photon traps" or CIPTs can serve as broadband and radiation-free "perfect" optical cavities. As such, CIPTs can control, slow and trap light in a manner similar to such celestial phenomena as black holes, strange attractors and gravitational lenses. This equivalence between the motion of the stars in curved spacetime and propagation of the light in optical metamaterials engineered in a laboratory is referred to as the "optical-mechanical analogy."

Zhang says that such specially designed metamaterials can be valuable tools for studying the motion of massive celestial bodies in gravitational potentials under a controlled laboratory environment. Observations of such celestial phenomena by astronomers can sometimes take a century of waiting.

"If we twist our optical metamaterial space into new coordinates, the light that travels in straight lines in real space will be curved in the twisted space of our transformational optics," says Zhang. "This is very similar to what happens to starlight when it moves through a gravitational potential and experiences curved spacetime. This analogue between classic electromagnetism and , may enable us to use optical to study relativity phenomena such as gravitational lens."

In their demonstration studies, the team showed a composite of air and the dielectric Gallium Indium Arsenide Phosphide (GaInAsP). This material provided operation at the infrared spectral range and featured a high refractive index with low absorptions.

In their paper, Zhang and his coauthors cite as a particularly intriguing prospect for applying artificial to the optical-mechanical analogy the study of the phenomenon known as chaos. The onset of chaos in dynamic systems is one of the most fascinating problems in science and is observed in areas as diverse as molecular motion, population dynamics and optics. In particular, a planet around a star can undergo chaotic motion if a perturbation, such as another large planet, is present. However, owing to the large spatial distances between the celestial bodies, and the long periods involved in the study of their dynamics, the direct observation of chaotic planetary motion has been a challenge. The use of the optical-mechanical analogy may enable such studies to be accomplished in a bench-top laboratory setting on demand.

"Unlike astronomers, we will not have to wait 100 years to get experimental results," Zhang says.

Source: Lawrence Berkeley National Laboratory (news : web)

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User comments : 22

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5 / 5 (1) Jul 20, 2009
Doesn't mass curve space and time to produce the effect or appearance of gravity?
5 / 5 (1) Jul 20, 2009
I'm all in favor of transformational optics, but this application is just ridiculous. Basically, they propose to create mock-up models that approximate postulated theoretical structure. But why bother? One could instead use arbitrarily accurate computational models, based on the exact equations involved, and simulate the same problem on a supercomputer. Compute capacity is getting cheaper and more abundant every day.
1 / 5 (1) Jul 20, 2009
not backward, outward
3.7 / 5 (3) Jul 25, 2009
Alizee - you predict nothing. Your "Aether Wave Theory" is total nonsense. I remember Zephir put forth the challenge to "find flaws" in the "theory" and I found upper AND lower limit math flaws by the bottom of the first page of your website... The Casimir effect is a FAR more cogent explanation of vacuum behavior, considering it's quantization and such. As an experimentalist who sits underneath a supercon magnet almost every day doing MAS NMR, I challenge YOU to build a device or make ANY predictions that GR or the standard model doesnt. Your ex-post-facto handwaving puts the capital "K" in "krackpot" and does a disgraceful disservice to passionate but broke scientists like me who KNOW THE VALUE of employing the Scientific Method: building a theory that is CONSISTENT w/ previous theory (i.e., Newtonian -> GR -> etc.), but can PREDICT something that previous theory cannot. AWT completely and UTTERLY fails at this - you can't even get your math right.
1.3 / 5 (15) Jul 25, 2009
..your ex-post-facto handwaving..
But I explained metamaterial properties of vacuum at many places on the web a well before the publication described in this article was ever published.


So I don't steal my ideas from anybody - I can say, this publication was predicted by AWT or it was even motivated by AWT, instead... ;-)
1.3 / 5 (14) Jul 25, 2009
...the Casimir effect is a FAR more cogent explanation of vacuum behavior, considering it's quantization and such...
Indeed, inside of our Universe everything is connected with everything - but can you really explain metamaterial behavior of vacuum by Casimir force? At least on the conceptual level?

Can you at least attempt for it?
1.5 / 5 (2) Jul 25, 2009
Testing relativity in a lab?
I suggest another title.
Mimicking relativity in a lab.
1.3 / 5 (15) Jul 25, 2009
..Mimicking relativity in a lab..
If vacuum foam is massive environment, then the scale doesn't matter, just principle. Indeed,a foam formed in condensing supercritical fluid or simmilar environment would be a much better environment, because such foam gets more dense under introduction of energy in the simmilar way, like soap foam under shaking - thus mimicking behavior of vacuum foam in much more realistic way.

The modelling of vacuum by solid state metamaterial foam works for light of very narrow range of wavelength only. Real vacuum adopts its behavior to energy density nearly exactly - so we cannot see rainbow behind gravitational lens, for example.
3 / 5 (1) Jul 25, 2009
Is there a rainbow (chromatic abberation)behind gravitational lens?

I am very interested to know that.
1 / 5 (14) Jul 26, 2009
Here are other experiments, which are modeling event horizon, Hawking radiation and other artifacts by foamy material environment. For example modern optical cables have structure of sponge, so they can be used for modeling of these optical phenomena, too.


So that the metamaterial behavior of vacuum isn't surprising at all for scientists, who are informed about subject. Just the malicious people, who want to prohibit publicity from such understanding are labeling my posts be minimal number of points possible repeatedly. They want to keep "their" science mysterious and secret like Holy Church in medieval era to keep their information monopoly.
5 / 5 (2) Jul 26, 2009
If somebody ranks a question made with 3/5 by a user named Alizee who ranks all Slotin sayings with 5, then I conclude

1 / 5 (2) Jul 26, 2009
Do you mean "schizotypal"? Certain terms are too complicated for me.

You see, you are very gifted to not making friends.

Occam's razor?
Why does space(time) bend?
Because light always goes in a straight line.
The latter is is an assumption that may or may not be true. Maybe that is where Einstein went wrong.
Einstein was besides a mathematician and a physicist a great communicator and entertainer, and not only that. You need these skills to become famous.
1 / 5 (2) Jul 26, 2009
And about religion.

They are also right as Paul said in one of his letters something you should read.

Though I speak with the tongues of men and of angels and have not love. I am become as sounding brass or a tinkling cymbal. And though I have the gift of prophecy, and understand all mysteries, and all knowledge, and though I have all faith so that I could remove mountains, and have not love, I am nothing.
1.3 / 5 (15) Jul 28, 2009
You see, you are very gifted to not making friends.
Friend of you, who is labeling unknown people a "schizotipical" personality? No, thank you - I've enough of friends, who don't call me in such way already.

For me sounds a bit funny, if person like you, who is labeling others like psychiatrist without asking mentors people, how to get friends..;-) The fact, you mistyped the name of my alleged disorder is symptomatic. This is simply very dull behavior .
1.3 / 5 (15) Jul 28, 2009
light always goes in a straight line
How can you explain gravitational lensing (or lensing effect in general), after then?
..you need these skills to become famous..
I don't need to become famous. If people become fammiliar with Aether theory, it will be quite enough for me. And while AWT has no personality disorder, i don't expect some social problem here.
1 / 5 (2) Jul 28, 2009
The fact, you mistyped the name of my alleged disorder is symptomatic.

It just means that English is not my native language. I learned psychiatry in Spanish which is also not my native language. That is where the typo came from.
1.3 / 5 (16) Jul 28, 2009
OK, try to explain gravitational lensing, if you believe in constant speed of light in vacuum. Shouldn't be vacuum completely homogeneous, after then? Where's the factual problem of light speed invariance interpretation?

A hint: http://aetherwave...tum.html
1.3 / 5 (15) Jul 28, 2009
Here's nothing schizotypal on Aether concept - it's illustrative and natural model of spatial probability distribution in random system without laws. Aether is just a physical representation of concept, everything, what we can see inside of Universe is driven by pure probability laws existing inside of high number of elements like inside of particles of chaotic gas - nothing else.
1 / 5 (1) Jul 28, 2009
Lets wait a couple of billion years. When the lensed objects we can see now moved away from the lensing object we have more data to draw conclusions.

But hey I feel that through that razor, just maybe Einstein went too far to put an end to Euclidian space.

I suddenly have an idea though how things stick together (another 2 cents theory on the limit of my knowledge)
I will make a nice animation to explain and when ready I might post it.
1.3 / 5 (15) Jul 28, 2009
The whole trick is, you cannot observe gravitational lensing and constant speed of light at the same place/moment, i.e. the interpretation of gravitational lensing by space-time curvature is incongruent. Many people have suddenly many ideas when reading about AWT...;-)
1 / 5 (1) Jul 28, 2009
That is why I wanted to know if there is chromatic aberration in gravitational lenses. That would not be consistent with spacetime curvature. But I think I read that the spacetime curvature is only cause of part of the bending. So that leaves relativity also with chromatic aberration. As far as I understand the bending effect is hardly measurable. Let alone chromatic aberration inside that effect. I don't think anybody has measured gravitational chromatic aberration.
1.3 / 5 (15) Jul 29, 2009
..if there is chromatic aberration in gravitational lenses...
Indeed it is - from exsintric perspective. From insintric perspective light always follows its most effective path, and space-time of observer follows such path as well, so no dispersion occurs here. As the example of chromatic aberration can serve GZK limit, for example. http://tinyurl.com/m9oltc

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