Did you know that all observable matter that we know of makes up less than 5% of all of the matter of the universe? It may seem unbelievable that this “normal” matter is such a tiny fraction of the matter in the universe, especially since we do not necessarily know what makes up the other parts. For the other 95%, we have given the names dark energy and dark matter, which make up about 68% and 27% of the universe respectively. On a general level, both of these are invisible. Dark matter is responsible for how galaxies are organized, and dark energy drives the expansion of the universe.
Dark Energy
Since so much of the properties of dark energy is unknown, what can people actually say about it. Well for one, NASA says that it affects the expansion of the universe. It is also a property of space. There are several theories about the properties relating to dark energy, one theorized by Einstein, who said that it was possible for more space to come into existence. This space contains its own energy, influenced by a cosmological constant. Since the universe is expanding, this would mean that more of this dark energy would appear, and creates an accelerating loop where more dark energy means more acceleration means more dark energy, etc. This can explain why galaxies seem like they are moving away from us at increasing rates – because they are. Another theory relates to the quantum theory of matter, which says that empty space is filled with temporary particles. However, the calculations that come from this do not make sense in a mathematical way, which does not make it a particularly viable explanation.
I will describe one more theory for dark energy, which says that Einstein’s theory of gravity is not correct. This means that we would need a new theory of gravity not only for the expansion of the universe and dark energy, but also for our solar system and normal matter. It would be interesting to see how a new theory could be created since our current theory of gravity mechanically works so well on our planet.
Dark Matter
So, what is dark matter? Seems like it could be pretty similar to dark energy just based on the name. Similarly to dark energy, we know very little about dark matter. We do know that it is not in the form of matter that forms stars and planets, its invisibility giving it its “dark” attribute. It also is not dark clouds of normal matter either. We do have ways of detecting dark matter, however. In gravitational lensing, matter acts as a lens by bending space and distorting light (Britannica). In the center of galaxies and clusters of galaxies, this “missing” normal matter can be explained by dark matter. Dark matter does seem to create a “halo” surrounding the normal matter in a galaxy or a cluster, and since it has mass, it influences how galaxies move inside this halo. It would be interesting to see more research done in both the domain of dark matter and energy, since it does make up basically all of our universe.
Is dark-matter the same thing as anti-matter? I don’t know much about astrophysics, but I think it’s absolutely crazy how our universe is built and the actual science and materials behind it (and being honest I don’t think I completely understand it either). I think it’s really interesting how you mentioned that even Einstein’s theory was wrong, so we need a new model, which demonstrates that we all still have a LOT to learn about the way life, the universe, and everything works. It’s been a pleasure reading your blogs! They definitely inspired me to look more into these topics.
It’s crazy to think how it took millennia for humans to gain even a basic understanding of how the world around us works, and how a lot of it seems to be completely wrong when applied to things that are really far away, like other galaxies. It just goes to show that the inner workings of the universe will probably never be something we completely understand.
It is astonishing that there is an entire category of matter that is defined by the fact that we know next to nothing about it. This reminds me of the time that they conducted a study to figure out how much what percentage of matter was baryons( regular matter) and only found half of what they expected to find. They thought the matter was just missing until they eventually realized it was hidden by this “dark” matter.