Scientists at Duke and Rutgers universities have developed a mathematical framework they say will enable astronomers to test a new five-dimensional theory of gravity that competes with Einstein’s General Theory of Relativity.
Charles R. Keeton of Rutgers and Arlie O. Petters of Duke base their work on a recent theory called the type II Randall-Sundrum braneworld gravity model. The theory holds that the visible universe is a membrane (hence “braneworld”) embedded within a larger universe, much like a strand of filmy seaweed floating in the ocean. The “braneworld universe” has five dimensions — four spatial dimensions plus time — compared with the four dimensions — three spatial, plus time — laid out in the General Theory of Relativity.
The framework Keeton and Petters developed predicts certain cosmological effects that, if observed, should help scientists validate the braneworld theory. The observations, they said, should be possible with satellites scheduled to launch in the next few years.
If the braneworld theory proves to be true, “this would upset the applecart,” Petters said. “It would confirm that there is a fourth dimension to space, which would create a philosophical shift in our understanding of the natural world.”
The scientists’ findings appeared May 24, 2006, in the online edition of the journal Physical Review D. Keeton is an astronomy and physics professor at Rutgers, and Petters is a mathematics and physics professor at Duke. Their research is funded by the National Science Foundation.
The Randall-Sundrum braneworld model — named for its originators, physicists Lisa Randall of Harvard University and Raman Sundrum of Johns Hopkins University — provides a mathematical description of how gravity shapes the universe that differs from the description offered by the General Theory of Relativity.
Keeton and Petters focused on one particular gravitational consequence of the braneworld theory that distinguishes it from Einstein’s theory.
The braneworld theory predicts that relatively small “black holes” created in the early universe have survived to the present. The black holes, with mass similar to a tiny asteroid, would be part of the “dark matter” in the universe. As the name suggests, dark matter does not emit or reflect light, but does exert a gravitational force.
The General Theory of Relativity, on the other hand, predicts that such primordial black holes no longer exist, as they would have evaporated by now.
“When we estimated how far braneworld black holes might be from Earth, we were surprised to find that the nearest ones would lie well inside Pluto’s orbit,” Keeton said.
Petters added, “If braneworld black holes form even 1 percent of the dark matter in our part of the galaxy — a cautious assumption — there should be several thousand braneworld black holes in our solar system.”
But do braneworld black holes really exist — and therefore stand as evidence for the 5-D braneworld theory?
The scientists showed that it should be possible to answer this question by observing the effects that braneworld black holes would exert on electromagnetic radiation traveling to Earth from other galaxies. Any such radiation passing near a black hole will be acted upon by the object’s tremendous gravitational forces — an effect called “gravitational lensing.”
“A good place to look for gravitational lensing by braneworld black holes is in bursts of gamma rays coming to Earth,” Keeton said. These gamma-ray bursts are thought to be produced by enormous explosions throughout the universe. Such bursts from outer space were discovered inadvertently by the U.S. Air Force in the 1960s.
Keeton and Petters calculated that braneworld black holes would impede the gamma rays in the same way a rock in a pond obstructs passing ripples. The rock produces an “interference pattern” in its wake in which some ripple peaks are higher, some troughs are deeper, and some peaks and troughs cancel each other out. The interference pattern bears the signature of the characteristics of both the rock and the water.
Similarly, a braneworld black hole would produce an interference pattern in a passing burst of gamma rays as they travel to Earth, said Keeton and Petters. The scientists predicted the resulting bright and dark “fringes” in the interference pattern, which they said provides a means of inferring characteristics of braneworld black holes and, in turn, of space and time.
“We discovered that the signature of a fourth dimension of space appears in the interference patterns,” Petters said. “This extra spatial dimension creates a contraction between the fringes compared to what you’d get in General Relativity.”
Petters and Keeton said it should be possible to measure the predicted gamma-ray fringe patterns using the Gamma-ray Large Area Space Telescope, which is scheduled to be launched on a spacecraft in August 2007. The telescope is a joint effort between NASA, the U.S. Department of Energy, and institutions in France, Germany, Japan, Italy and Sweden.
The scientists said their prediction would apply to all braneworld black holes, whether in our solar system or beyond.
“If the braneworld theory is correct,” they said, “there should be many, many more braneworld black holes throughout the universe, each carrying the signature of a fourth dimension of space.”
SOURCE: Duke press release
I cannot approve this news because is an unethical news (not from sciencebase of course but from original source).
String (brane) theory cannot compete with general relativity and string theory predicts anything, the rest is pure hype.
See Hype from the Swampland
for more information and links to previous hypes published in media.
The current status of string theory and the full nonsense is published around the field remember me the famous Sokal affair. Remember?
Nobel winner Sheldon Glashow, one of multiple critics of string theory repeated the Sokal Affair (but now in physics), publishing a supposed verification of string theory a year ago.
String theory specialists were unable to see that was a joke :-) See Lubos Motl review of the paper (Glashow finds the correct stringy vacuum)
Matti Pitkanen wrote:
I would carefully recommend to science writers do not follow the hype generated around string theory not the unethical spreading of the “theory” in mass media.
Further reading:
Twenty Years After
Juan R.
Center for CANONICAL |SCIENCE)
To sciscoop readers:
It’s odd to see that a single negative comment stopped people from voting on the article. Just think for a second why you personally do not want to vote on it. Because it stirs a discussion? If you vote for it someone will think ill of you? What is it?
I noticed that a while ago – a touch of controversy, a trivial typo, a little doubt and everyone but a few stop voting. They don’t vote for, or against, not even abstain. They just hide. Why? Any rational answer?
Stand up and vote. For or against. You have nothing to loose.
Let’s get it to the front page and have a discussion. That’s the whole purpose of this site.
The point of this news is different from what you seem to think. They are proposing a realistic experiment that would permit falsification of a particular theory. Yes, the majority of the 1020 string theories predicts anything and everything and cannot be tested. So, when someone comes up with a way to test predictions of a particular theory he should not be branded “unethical”.
If you know any better way to do science than by proving theories through experimentation, please enlighten me.
Unfortunately, you appear to not understand my comment. Unfortunately the “Science News” was approved and posted in sciscoop ignoring my advice.
Fortunately, after of posting my comment a blog comment on the news with similar points to mine appeared here
String Theory Makes Prediction – Pig Grows Wings
People can still obtain a more accurate version.
P.S: A bit of topic but anyone interested in current status of string theory would read future (September) book by quantum gravity specialist Lee Smolin:
Juan R.
Center for CANONICAL |SCIENCE)
You are wrong in a different place than you think. I am not contesting the fact that the journalist in this particular article overhyped the event. OK? Thus the point #1 is settled. I am not contesting the fact that there is a problem with string theories in general – they can predict anything and thus cannot be falsified. That’s point #2 that you keep brining up, and no one is arguing with you. OK? No need to prove #1 and #2. Peace.
The issue is different. First, Sciscoop is a place to discuss science news (or, in reality science-related news). Consequently, there is nothing unfortunate that the piece got through the moderation queue. It is science and thus can be discussed here. We are having a discussion. The Sciscoop’s purpose is served.
Second, the guy you cited basically claims that the proposed experiment won’t yield positive results. Fine. I even agree with him. But if the experiment is done right, even a negative result is valuable. That’s the beauty of experimental science. Negative result is still a result. OK?
In science, there is only observation, theory to explain the observation, and experiments to test whether that theory remains valid for another instance of the observation.
There is no such thing as scientific proof. Just because the sun rises every morning and has done for billions of years, doesn’t mean it will tomorrow. We have a theory to explain why it happens, but and observation that contradicted the theory (the sun not rising, in other words) would invalidate it and we’d have to devise a new theory.
Same goes for the variou cosmological theories. It just happens that some of them are yet to be tested experimentally and thoughts of Occam’s Razor come to mind when theories are constructed that are intestable and explain reality in a far more complex way than a current theory.
Just a quick flip of my 2c
db
If the earth is flat, then we should not observe a circular shadow on the moon during a lunar eclipse. But, we do, the earth must be round.
BUT.
We make an awful lot of assumptions about that observation don’t we? (the following is adapted from http://www.personalityresearch.org/metatheory/flatearth.html by G Scott Acton of Northwestern University) .
First, we assume that the sun illuminates the moon.
Secondly, we assume it is the earth and not something else between sun and moon during a lunar eclipse.
Thirdly, we assume universality of the behaviour of light.
Fourthly, we assume that earth’s rotation doesn’t affect the shadow cast.
Fifthly, we assume that no other heavenly bodies intervene.
Finally, we also assume that optics can tell us the difference between a curved and flat shadow.
Now, let’s assume the earth is flat, but round, like a quarter…then our fourth assumption could be demonstrated to be wrong and so prove that the earth may indeed be flat. If you spin a quarter, the shadow it casts will be a circle.
It is widely acknowledged that the earth is spinning at 1000 miles per hour, so surely the shadow it casts would be a circle just like the spinning quarter.
Clearly, the earth should cast a circular shadow!
DaveB
Yes, the one you found is fun.
If you spin a quarter, the shadow it casts will be a circle – but it won’t be solid. A fraction of light (defined by the ratio of Earth’s disk thickness to its diameter) would pass through :-P
A while ago, I think in the late 70s, I read an ideologically similar theory. It was published as a mind exercise in some popular science magazine (not Popular Science). The theory claimed that the Universe was really a spherical bubble surrounded by a hard surface. The hard surface was Earth. We lived on the inside of the surface. The light traveled not in straight lines, but in circles going through the center of the Universe. The closer it got to the center, the slower it went. The article was asking readers to pick inconsistencies and to suggest ways to fix them.
Yes the shadow “intensity” would be the giveaway, but I am sure there’d be a way to construct the argument to take that into account by inventing some other assumption about the way light behaves when it passes near a flat spinning disk…
d
I want not continue this discussion, however I see obligated to fix some points with the aim of clarifying the entire thread.
1) I titled my first message as “The news is unethical and would be not published” and offered some justification on my position.
The original news sure us that a new theory of gravity based in 5D brane theory (a recent modification of traditional string theory: strings are 1-branes) could compete with general relativity and would be tested in a future experiment. Nothing of that was true. There is not consistent theory of gravity on string-brane models, and there is not falsifiable models.
2) Then jdoe said
Precisely one of my two main points was there was not such one “particular theory”, just the traditional hype of last 40 years.
3) Then clarified my point (at least that I thought) and offered additional data on why news was unethical and no competitor or falsifiable model had been published. I included quotes as
and a link to future book on the topic claiming in public that academicians and workers in gravity know during many years:
4) Now jdoe argues that he agree on “the journalist in this particular article overhyped the event.” And that “there is a problem with string theories in general […] cannot be falsified”
but your original criticism to my post was
I said nothing on scientific method (precisely highlighted that string theory is not scientific at all). I critiqued the unethical character of the news (the excessive hype beyond reality) and I argued that the proposed brane model was not testable!
And now adds
I simply warned of the unethical character of the news and recommended was not published since had little science on it. People can agree or disagree with me, but I also can and I can state my opinion here. For me, the publishing of the news in sciscoop was unfortunate.
The problem with string, brane, and M theory is that can predict anything and the contrary to anything. If the property X is measured in a future experiment, any result for X will be compatible with string theory, just changing parameters. In fact, the history of the discipline is full of that. Therefore, both positive and negative result (you state) are compatible with string theory and the hype self-perpetuate.
Negative result is not “ok” (because do not falsify the model) and reason of some quotes I cited.
—–
I am also glad that media begins to discover the great fiasco of string theory (i.e. like public has been misinformed during some decades with string theory promises by means of dishonest news, books, and some TV series).
Nothing gained in search for ‘theory of everything’
Just as you’ve solved every problem in the Universe, the string breaks
The dean of debunking
P.S: Even if you do not know difference between observation and experiment, it exists and is reason that disciplines as cosmology are considered to be in the limit of natural science whereas atomic physics or molecular chemistry for instance are full sciences.
In string (brane and M) theory there is not observation or experiment possible therein is not scientific: you can call it proto-science, metaphysics, or even religion.
Juan R.
Center for CANONICAL |SCIENCE)
The visible universe is a membrane or translucent film. Our side is populated with galaxies, stars, planets and black holes (including, supermassive black holes). The flipside of the film has a similar configuration; however, supermassive black holes on this side are the center of white holes that generate the galaxies on the reverse side. Conversely, the SMBH on the reverse generate our galaxies. Smaller black holes on the reverse create our stars on the obverse. On the reverse, prodigious amounts of energy is sucked into black holes to emerge through the white holes on the obverse to give birth to our stars and our galaxies. Our black holes and SMBH suck in matter to spit out energy systems on the reverse. The flux between the two creates the warp in time, space and gravity that we are unable to measure from this side alone.