We are pretty sure they exist though. So, what can we know? Dark matter is that the stuff that creates it possible for galaxies to exist. When we calculated why the universe is structured the way it’s , it quickly became clear that there is just not enough normal matter. The gravity of the visible matter isn’t strong enough to make galaxies and sophisticated structures. The stars would more likely be scattered everywhere the place and not form galaxies. So, we all know there’s something else inside and around them. Something that does not emit or reflect light.

      Something dark… but besides having the ability to calculate the existence of substance , we can see it… kind of. Places with a high concentration of substance bend light passing near by. So we all know there’s something there that interacts with gravity. Right now, we’ve more ideas about what dark energy isn’t , than what it is! We know substance isn’t just clouds of normal matter without stars, because it might emit particles we could detect. 

     Dark matter isn’t anti-matter, because anti-matter produces unique gamma rays when it reacts with normal matter. Dark matter is additionally not made from black holes, very compact objects that violently affect their surroundings, while substance seems to be scattered everywhere the place. Basically, we only know 3 things for sure; 

1. Something is out there. 

2. It interacts with gravity. 

3. there’s tons of it.

      Dark matter is perhaps made from a sophisticated exotic particle that doesn’t interact with light and matter during a way we expect, but immediately , we just do not know . Dark energy is even weirder and mysterious. We can’t detect it, we will not measure it and that we can’t taste it. But we do see its effects very clearly. In 1929, Edward Hubble examined how the wavelength of sunshine emitted by distant galaxies, shifts towards the red end of the spectrum because it travels through the space. 

He found that fainter, more distant galaxies showed an outsized degree of red shift; closer galaxies, not such a lot . 

     Hubble determined that this was because the universe itself is expanding. The Doppler effect occurs, because the wavelengths of sunshine are stretched because the universe expands. More recent discoveries have shown that, the expansion of the universe is accelerating.

      Before that, it had been thought that the pull of gravity would cause the expansion to either hamper or maybe retract and collapse in on itself at some point. Space doesn’t change its properties because it expands; there’s just more of it. New space is consistently created everywhere, galaxies are tight bound clusters of stuff held together by gravity so we do not experience this expansion in our daily lives. But we see it everywhere around us. 

     Wherever there’s empty space within the universe, more is forming every second. So, dark energy seems to be some quite energy intrinsic to empty space. Energy that’s stronger than anything we all know and it keeps getting stronger as time passes by. Empty space has more energy than everything else within the universe combined. We have multiple ideas about what dark energy could be . 

One idea is, the dark energy isn’t a thing, but just a property of space. Empty space isn’t nothing, it’s its own energy. It can generate more room and is sort of active. So, because the universe expands, it might be that just more and more room appears to fill the gaps and this results in a faster expanding universe. This idea is on the brink of a thought that Einstein had back in 1917, of the concept of a constant , a force that counteracted the force of gravity. 

      The only problem is, that once we tried to calculate the quantity of this energy the result was so wrong and bizarre , that it only added to the confusion. Another idea is, that vacant space is really filled with temporary, virtual particles that spontaneously and continually form from nothing then dissapear into nothing again. The energy form those particles might be dark energy. Or maybe dark energy is an unknown quite dynamic energy fluid or field which permeates the whole universe, but somehow has the other effect on the universe than normal energy and matter.

      But if it exists, we do not skills and where or how we could detect it. So there are still tons of inquiries to answer. Our theories about substance and dark energy are still just that; theories. On one hand, this is often quite frustrating, on the opposite hand this is often frontier science making it very exciting. It shows us that regardless of what proportion we feel we’re on top of things, we are still considerably apes with smartphones, on a tiny fragile island in space looking into the sky wondering how our universe works There is such a lot left to find out , which is awesome right…!