Space is everywhere. Energy and matter are continuously in motion.
Energy and matter change and conform to the forces that direct them, giving them duration, coherence, shape, and form. These forms eventually decay, devolving back into space.
Standard models in physics and astronomy predict that the universe is expanding, that space is flexible, perhaps even multidimensional. We have compiled sliced images of the large scale structure of space.* There are proposed universe’s with boundaries, without boundaries, with holes like Swiss cheese, elastic models, rigid models, etc.
Since the time of Galileo, the scientific method has been employed to interpret and describe the external world. Yet, as individuals, we inhabit the center of a unique perspective. We experience the world in proportion to our sensory and perceptual limitations. Still, scientists have learned to collect data in reliable and elegant fashion, in the service of truth, despite their profound perceptual biases.
And yet we can easily visualize an expanding universe as having a spherical shape, simply because of our knowledge of physics. Or perhaps because the planet we live on is spherical. We also know that our solar system and galaxy are spinning, orbiting systems.
The regions of our brain that are responsible for comprehending whole to parts relationships may have evolved as an adaptation to this primary form. Or maybe our brains simply make the jump from a spinning planet to a spherical universe by association.
However, that doesn’t mean that the shape of the universe is necessarily spherical or egg-shaped, or is even limited by a boundary.
Perhaps we can be sure of only one thing: that the shape of the universe is the shape of space, of matter and energy everywhere, ongoing.
* see Margaret Geller and John Hukra, Smithsonian Observatory, Harvard University