The universe is usually believed to be increasing at an accelerating fee, because of a mysterious drive dubbed dark energy. However how precisely does this drive work? Researchers within the UK have performed an experiment to check a speculation that this fifth elementary drive works on single atoms – and located no hint of it.
Darkish vitality was “found” in 1998, when physicists realized that the enlargement of the universe wasn’t slowing down, as they anticipated. As a substitute, it appeared to be doing the precise reverse. Additional observations over time have backed up the idea, and now it is a broadly accepted clarification that explains numerous weirdness in the usual mannequin of cosmology.
However what’s darkish vitality, precisely? No person actually is aware of, nevertheless it seems to be a fifth elementary drive, with the recognized 4 being gravity, electromagnetism and the sturdy and weak nuclear forces. No matter darkish vitality is, it appears to behave virtually like the other of gravity, strongly pushing matter away from all different matter as a substitute of pulling it collectively.
One department of theories means that darkish vitality will get weaker the extra matter is round it, that means it is at its strongest out within the vacuum of area. That might additionally clarify why some earlier exams to detect it got here up empty – they had been utilizing giant weights, which might have decreased the impact of the drive.
So a group from the College of Nottingham and Imperial Faculty London devised new experiments to check this principle. They got down to examine the interactions between a big and a small weight. On this case, the “giant” weight was a metallic ball the scale of a marble, whereas the small weight was a single atom.
The researchers positioned the ball in a vacuum chamber, then dropped atoms round it. The thought was that if there was a fifth drive appearing between the 2 weights, and it behaved the best way this principle advised, then the trail of the atom ought to bend barely because it handed the marble.
After working these exams, the group discovered no hint of any such drive. That successfully guidelines out this explicit principle, which might even have required modifications to the idea of gravity. Equally, one other current research dominated out “chameleon” particles from the Solar as carriers of the drive.
However a null outcome is not affirmation that darkish vitality itself would not exist – it simply means it may very well be hiding elsewhere, and we have now narrowed the search.
“This experiment, connecting atomic physics and cosmology, has allowed us to rule out a large class of fashions which were proposed to elucidate the character of darkish vitality, and can allow us to constrain many extra darkish vitality fashions,” says Ed Copeland, lead creator of the research.
The brand new experiments might additionally add to a pile of accelerating proof that the darkish vitality principle itself is fallacious. Different different explanations embody “Tardis” regions of spacetime which can be greater on the within, a “dark fluid” with detrimental mass, or that by simply accounting for the altering construction of the cosmos, the need for dark energy as a stand-in vanishes. Some even name into question the validity of the unique discovery that the enlargement of the universe is accelerating.
With so many questions surrounding this mysterious drive, little question many extra research might be performed to attempt to unravel the enigma.
The analysis was printed within the journal Physical Review Letters.
Supply: Imperial College London