We may have got it all wrong about the shape of the Universe

Scientist reveal that competing studies suggest our existing models for the shape of the Universe may need totally revising.

Nov 19, 2019 |
3 min read

We all know the Universe, right? Big thing, full of stars and planets. Constantly expanding on a sort of flat plane. Well, it turns out we may not know it half as well as we thought we did.

The traditional model of the Universe has seen it as ‘flat,’ an image based on, and borne out by, repeated observation and measurements from numerous different sources, but new evidence suggests that the picture astrophysicists have extrapolated from this data is misleading. In fact, according to readings from the European Space Agency’s Planck telescope, the Universe may not be a ‘flat’ shape, where lines extend out in ever-expanding ways into infinity but instead be a ‘closed’ shape, a sphere-like our own planet, where lines curve back round on themselves.

This change of thinking could be a disruption in our understanding of the cosmos, so shattering that it will require a total redraw and the contemplation of some funky new physics to explain what we’re seeing. Or it may be an anomaly, a fluctuation in an otherwise consistent picture.

Our image of a flat plane Universe has been built up from many different observations across many different observatories but the datasets gained from these myriad institutions over time have been collated and compiled based on particular sense of how they should fit together when, in reality, these data are not actually measured in the same consistent way, or even from the same cosmological model. Therefore the conceptual framework we try to fit them into or measure them against really matters.

The differences they have presented from one another have traditionally been flattened out (see what I did there…?) into the flat Universe model, with attempts made to excuse, explain away or ignore some of the more troubling inconsistencies. However, the new Planck data suggests such inconsistencies may, in fact, make perfect sense, providing you allow for a closed shape to the cosmos.

The key discovery of the Planck telescope was an “enhanced lensing amplitude in cosmic microwave background power spectra” which, in layman’s terms means that that the CMB (or Cosmic Microwave Background), the background radiation leftover from the Big Bang (a very faint and cold trace energy which can be found absolutely everywhere in the Universe), can be seen to bend more than it should, or at least more than can be accounted for by the objects between us and it.

Einstein predicted and proved the concept of gravitational lensing the idea that space itself is curved by the gravity, or mass, of the objects in it, a phenomena which can be observed by the displacement of distant stellar objects, whose light has been curved in its path by intervening massive objects.

However, the idea that the Universe itself is a curved sphere, closing in on itself at the edges, is new, exciting, and, as yet, as hotly contested as it is totally unproven. The anomalous bending could be a mere fluctuation, it could be something unseen, but the team from the ESA is confident that not only is the bending consistent with a closed model of the Universe but that this may be the best explanation for what they have found.

The ESA has already used previous Planck experiments to examine the CMB (discovering, in the process, that the Universe was slightly older than had been thought) but the cosmological crisis they may have unveiled is next-level stuff.

That said, when it comes to the closed Universe model, here are a lot of things going against it. For one thing, all previous analysis of Planck data has been consistent with the flat Universe model, for another that famously tricksy Hubble Constant only gets harder to predict if you place it in a closed Universe model and equally both cosmic shear data and baryon acoustic oscillation surveys of dark energy are inconsistent with a closed Universe model.

So do we need to rethink space as we know it? Only time and a lot more data will tell.

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