Getty Images/Suvendu Giri
- A new paper uses string theory to propose a new model of the universe.
- The researchers think our universe may be riding a bubble expanded by dark energy.
- All matter in the universe may exist in strings that reach into another dimension.
Our universe may be having itself quite a great time it seems. Cosmologists from Uppsala University came up with a new model that proposes the universe may be riding on an ever-expanding bubble in an extra dimension.
In particular, according to this theory, published in Physical Review Letters, the researchers offer a novel explanation for how the universe may be getting bigger. The fact of its accelerating expansion has been known for about the past 20 years but the explanation for that has relied rather unsatisfyingly on the mysterious "dark energy".
In their new paper, the Swedish scientists approach this topic from the direction of string theory, which maintains that all matter is made of tiny vibrating strings. The theory also allows for the existence of extra dimensions, in addition to the three spatial ones we experience on a daily basis.
The groundbreaking new idea by the researchers says that the universe may be sitting on the edge of an expanding bubble, while all matter exists on strings that reach outward from it into an extra dimension. Dark energy would be the inflating force in this bubble, the existence of which is supported by string theory, claim the scientists.
In case you're wondering, they think such bubbles should be rather stable, writing there's "a strong indication in favor of the stability of these bubbles."
Perhaps even more excitingly, there could be more bubbles than just the one with our universe on it. Each one of those carrying another universe.
'In this context, the cosmology we see as 4D observers is not due to vacuum energy, but rather arises as an effective description on a dynamical object embedded in a higher dimensional space,' the researchers explain.
The Uppsala University team included Souvik Banerjee, Ulf Danielsson, Giuseppe Dibitetto, Suvendu Giri, and Marjorie Schillo.
As they write in their paper, black holes can also be re-defined by this new theory:
"Gravitational collapse of the string endpoints in four dimensions results in an unstable black string solution in five dimensions," state the scientists.
Check out their research for yourself here.
Michio Kaku: The multiverse has 11 dimensions
Image source: Sereno, et al
Mind & Brain
- A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
- The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
- This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.
Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).
A neural crêpe
A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.
So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.
The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."
Study's cross-sections of a folded cerebellum
Image source: Sereno, et al.
A complicated map
Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."
That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.
It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."
This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."
Bigger and bigger
The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.
"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."
As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."
Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."
