SoylentNews is people
SoylentNews
More than 40 years ago, a leading relativity theorist made a surprising prediction. Whereas empty space should feel immeasurably cold to any observer gliding along at a constant speed, one who is accelerating, say because he's riding a rocket, would find empty space hot. This so-called Unruh effect seemed practically impossible to measure, but now four theorists claim they have devised a doable experiment that could confirm the underlying physics. Skeptics say it will do no such thing—but for contradictory reasons.
"The hope is that this will convince skeptics that the whole thing is coherent," says Stephen Fulling, a theoretical physicist and mathematician at Texas A&M University in College Station who was not involved in the work. But Vladimir Belinski, a theorist at International Network of Centers for Relativistic Astrophysics in Pescara, Italy, says, "The Unruh effect is nonsense, it's based on a mathematical mistake."
[...] The effect is too feeble to measure directly. To see the vacuum heat to 1 K, an observer would have to accelerate 100 quadrillion times faster than the best rocket can. But Daniel Vanzella, a theorist at the University of São Paulo in São Carlos, Brazil, and colleagues argue that it should be possible to detect the key thing—the fog of photons seen by the accelerating observer—by studying light radiated by electrons. [...] Vanzella and colleagues start their analysis in the accelerating frame, where they assume the circulating electrons encounter that fog of photons. The electrons will both absorb photons from and radiate photons into the fog. Weirdly, every event in the accelerated frame in which the electrons absorb or emit a photon corresponds to an event in the lab frame in which the electrons emit a photon. The theorists use relativity theory to predict the spectrum of emitted photons in the lab frame, as they report in a paper in press at Physical Review Letters.
The Unruh effect (or Fulling–Davies–Unruh effect) "is the prediction that an accelerating observer will observe blackbody radiation where an inertial observer would observe none. In other words, the background appears to be warm from an accelerating reference frame; in layman's terms, a thermometer waved around in empty space, subtracting any other contribution to its temperature, will record a non-zero temperature. The ground state for an inertial observer is seen as in thermodynamic equilibrium with a non-zero temperature by the uniformly accelerating observer."
(Score: 4, Insightful) by Zinho on Tuesday April 18 2017, @03:20PM (6 children)
Not a bad bit of reporting. let me take a stab at a layman's summary:
* one researcher has a theory, which he says is testable with today's equipment; if he's right, then light will be emitted by accelerating electrons at a predicted wavelength
* another researcher says that the experiment will show the predicted result, but for a different reason, and that the first researcher's model of the universe is incorrect
* A third researcher says that the first researcher's model of the universe is correct, but his analysis is wrong and that the predicted photons will not be emitted
So the first researcher is looking for funding to get time on a particle accelerator to see what happens. We've got the labs and know-how needed to make this happen, but no one's really looked at the system this way before.
The second researcher is hoping for the predicted result, and will try to get funding for a follow-up experiment to show that his model of the universe is better than the first researcher's one.
The third researcher is hoping for a negative result, because otherwise he has to revise his worldview as well.
This is the kind of thing I'd like to keep my eye on, with an endless bucket of popcorn to go with it (it's going to take a while to work this out no matter the result). Good article!
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin
(Score: 3, Insightful) by maxwell demon on Tuesday April 18 2017, @07:10PM (4 children)
Or in short, science as it is meant to be: An experiment decides a disagreement between theorists.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by Zinho on Tuesday April 18 2017, @08:00PM
Or in short, science as it is meant to be: An experiment decides a disagreement between theorists.
Exactly! Well put.
For me, the popcorn-worthy drama is the two disagreeing scientists who each believe that either a positive or a negative result will support their side of the disagreement. :P
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin
(Score: 2) by kaszz on Tuesday April 18 2017, @10:21PM
Can't have that. My magic book says it can't be so and anyone that disagree must be beheaded.. ;-)
(Score: 2) by wisnoskij on Wednesday April 19 2017, @12:09PM (1 child)
Is that not the opposite of this situation?
No matter the result, it will "confirm" a host of separate and incompatible theories. One scientist will take it as proof that their is no Unruh effect another will take it as proof that their is a Unruh effect.
(Score: 2) by maxwell demon on Thursday April 20 2017, @04:52AM
No need to use square quotes. Yes, the experiment might confirm several theories. Guess what? With one bit of information you cannot distinguish three different possibilities. The important thing is that no matter the result, the experiment will falsify at least one theory. That is what experiments are for.
There will never be a set of experiments that narrows down the set of possible theories to just one. This is a logical impossibility. But every good theory allows experiments that falsify it, and every good experiment falsifies at least one theory.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 1) by Demena on Wednesday April 19 2017, @02:56AM
You might want to google 'MiHsC' as you will find a good explanation of why Unruh radiation may account for the phenomenon of inertia.