Dark Matters of the Universe Dark Matters of the Universe
Photo by Matt Gross/Unsplash
Outer Space, Science

Dark Matters of the Universe

The Invisible in Astronomy
Piotr Stankiewicz
time 9 minutes

Dark companions, dark matter, dark energy: astronomy finds the invisible more interesting than that which glows.

Some statements sound trite, but they are worth uttering anyway; and once we do utter them, they turn out not to be so trite after all. Take the (quite obvious) idea that, throughout the bulk of its history, astronomy’s only research material has been electromagnetic radiation reaching the Earth from space. The last several decades of new technology and space flights are but a tiny fraction of history. Most of the time, what the human study of space amounted to was this: we watched the visible spectrum as it arrived from the sky (in the 20th century, we also had radio waves and other electromagnetic spectra to contemplate), trying to analyse and make sense of our observations.

Once we have reached that conclusion, we are only a step away from another semi-trite remark: it’s the glowing stuff that astronomers like the most; whether it’s an astral body’s own light (that of stars, galaxies or, to name a less obvious example, meteors) or reflected light (planets, comets or moons). There needs to be some sort of light if we are to observe the object directly. That which is dark (and thereby doesn’t radiate and is not within an electromagnetic spectrum we can grasp) can only be detected indirectly – and that obviously makes the


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The black hole in the photo contributes to the formation of stars a million kilometres away. Source: X-ray: NASA / CXC / INAF / R. Gilli et al; NRAO / VLA radio; Optical: NASA / STScI
Outer Space

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The Life Cycle of Stars
Piotr Stankiewicz

Stars have their own life cycle: they are born, change and die, often bringing to life another star. And so it goes on…

Although this text is devoted to the evolution of stars, the first explanation is not related to astronomy but semantics. This is necessary because the concept of ‘evolution’ means something different than in the context of Darwin’s theory. Biological evolution refers to changes occurring within a certain species over the course of thousands and millions of generations. The evolution of stars is different, because it refers to the life cycle of a single star – from birth until death. Stars have no DNA and are not regulated by the fundamental principle of the animate world, namely that ‘like generates like’. They do not inherit, fight for existence or partake in the ‘survival of the fittest’. The evolution of stars is a term that has been accepted in astrophysics, but it would probably be more accurate to employ the more poetic term ‘life of stars,’ or, to borrow straight from Ovid, ‘metamorphoses of stars’.

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