![]() ![]() So as the universe expands, it could be that just more and more space appears to ‘fill the gaps’, and this leads to a faster-expanding universe. Empty space is not ‘nothing’-it has its own energy, it can generate more space and is quite active. One idea is that dark energy is not a ‘thing’ but just a property of space. We have multiple ideas what dark energy might be. Empty space has more energy than everything else in the universe combined. So, dark energy seems to be some kind of energy intrinsic to empty space-energy that is stronger than anything else we know and that keeps getting stronger as time passes by. Wherever there is empty space in the universe, more is forming every second. ![]() Galaxies are tight bound clusters of stuff, held together by gravity so we don’t experience this expansion in our daily lives, but we see it everywhere around us. New space is constantly created everywhere. Space doesn’t change its properties as it expands there’s just more of it. ![]() Before that, it was thought that the pull of gravity would cause the expansion to either slow down or even retract and collapse in on itself at some point. More recent discoveries have shown that the expansion of the universe is accelerating. The redshift occurs because the wavelengths of light are stretched as the universe expands. Hubble determined that this was because the universe itself is expanding. He found that fainter, more distant galaxies showed a large degree of redshift closer galaxies, not so much. ![]() In 1929, Edwin Hubble examined how the wavelength of light emitted by distant galaxies shifts towards the red end of the electromagnetic spectrum as it travels through space. We can’t detect it, we can’t measure it and we can’t taste it. We know dark matter is not just clouds of normal matter without stars, because it would emit particles we could detect.ĭark matter is not antimatter, because antimatter produces unique gamma rays when it reacts with normal matter.ĭark matter is also not made up of black holes, very compact objects that violently affect their surroundings, while dark matter seems to be scattered all over the place.īasically we only know three things for sure:ĭark matter is probably made up of a complicated exotic particle that don’t interact with light and matter in a way we expect-but right now we just don’t know.ĭark energy is even more strange and mysterious. Right now we have more ideas about what dark matter is NOT, than what it IS. Places with a high concentration of dark matter bend light passing nearby, so we know there’s something there that interacts with gravity. Something dark …īut besides being able to calculate the existence of dark matter, we can see it-kind of. Something that doesn’t emit or reflect light. So we know there is something else inside and around them. Stars would more likely be scattered all over the place and not form galaxies. When we calculated why the universe is structured the way it is, it quickly became clear that there is just not enough ‘normal’ matter-the gravity of the visible matter is not strong enough to form galaxies and complex structures. So, what DO we know?ĭark matter is the stuff that makes it possible for galaxies to exist. We really have no clue what dark matter and energy are, or how they work. This is kind of strange because it suggests that everything we experience is really only a tiny fraction of reality. About 25 per cent is dark matter and 70 per cent dark energy. This matter accounts for less than 5 per cent of the known universe. Matter as we know it: atoms, stars and galaxies, planets and trees, rocks and us. ![]()
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