Universe as a doughnut hole? New astrophysics perspectives challenge flat pancake theory

Interestingly enough, many astrophysicists are unconcerned by the universe's shape. Given the vast scale of their research, a lot of their intriguing findings are not dependent on this particular characteristic. A parallel can be drawn to human scientific inquiry about the Earth, where, despite initial ignorance of its topography and features, we still managed to extensively learn about its flora and fauna. Yet, keen scientists are closely studying the universe's form, and it seems the prevailing flat pancake theory is beginning to wobble.

Three primary factors lead scientists to consider the universe as flat:

• the light remaining from the Big Bang,
• the universe's rate of expansion,
• the evolution of matter and light within the universe.

Astrophysicist David Spergel has challenged these assumptions, particularly the first one. He carried out a study of the irregularities in relic radiation (cosmic microwave background) - the light leftover from the Big Bang. Utilizing data from WMAP and Planck probes, he proposed that the observed irregularities in radiation effectively negate each other, implying a flat universe with no curvature.

It's important to clarify that when we say the universe is geometrically flat, we don't mean flat in the ordinary sense of the word. From a geometrical perspective, a shape like a cylinder is considered flat. To understand, try drawing parallel lines on a piece of paper, then roll the paper so the linear ends meet – the resulting shape won't appear flat to the naked eye, but in geometric terms, it is, as the drawn lines never intersect.

In contrast, the Earth isn't geometrically flat, as its lines of longitude meet at the poles. Similarly, the universe has no such intersecting points, hence it's likened to flat shapes like a pancake or a Möbius strip.

However, since Spergel concluded his research in 2003, analysis of relic radiation has continued. After two decades, some astrophysicists argue that excessive deviations from his original data and perspective, along with the observed anomalies that can't be explained by the presence of black holes and galaxies, are causing uncertainty. These experts assert that they're not necessarily claiming the universe is curved, but rather, the accepted assumptions might be flawed. This includes the belief that the universe "wraps" around itself in only one dimension, and a complex multi-dimensional rounding is just as possible.

Scientific experts intend to review past observations of relic radiation, exploring alternative shapes of the universe. One such contender for a new model is a three-dimensional toroid or a similar shape. This leads some to suggest that the universe might resemble a doughnut with a hole. However, this theory implies an infinite, multi-dimensional doughnut, and it's just one of several options derived from previously discarded models of the universe that are up for reconsideration.