by a spin to field that's gravitational radiation or gravitons if you quantize it and so for gravity it's just the other way around again like charges attract and unlike charges repel keep in mind that for gravity the charge is the gravitational mass this means if there is anti-gravitating matter it would be repelled by the stuff we are made of but clump among itself indeed it could form planets and galaxies just like ours the only way we would know about it is its gravitational effect that sounds kind of like dark matter and dark energy right indeed that's why i thought it would be interesting because i had this idea that anti-gravitating matter could surround normal galaxies and push in on them which would create an additional force that looks much like dark matter normally the excess force we observe is believed to be caused by more positive mass inside and around the galaxies but aren't those situations very similar more positive mass and side are negative mass outside pushing in and if you remember the important thing about dark energy is that it has negative pressure certainly if you have negative energy you can also get negative pressure somehow so using anti-gravitating matter to explain dark matter and dark energy sounds good at first sight but at second side neither of those ideas work the idea that galaxies would be surrounded by antigravitating matter doesn't work because such an arrangement would be dramatically unstable remember the anti-gravitating stuff wants to clump just like normal matter it wouldn't enclose galaxies of normal matter it would just form its own galaxies so getting anti-gravity to explain dark matter doesn't work even for galaxies and that's leaving aside or the other evidence for dark matter and dark energy well the reason that dark energy makes the expansion of the universe speed up it's actually not that it has negative pressure it's that the ratio of the energy density over the pressure is negative and for antigravitating matter they both turn negative so that the ratio is the same contrary to what you expect that does not speed up the expansion of the universe another way to see this is by noting that antigravitating matter is still matter and behaves like matter dark energy on the contrary does not behave like matter regardless of what type of matter this is why i get a little annoyed when people claim that dark energy is kind of like anti-gravity it isn't so in the end i developed this beautiful theory with the new symmetry between gravity and anti-gravity and it turned out to be entirely useless what did i learn from this well that i wasted a considerable amount of my time on this was one of the reasons i began thinking about more promising ways to develop new theories clearly just guessing something because it's pretty is not a good strategy in the end i wrote an entire book about this today i try to listen to my own advice at least some of the time i don't always listen to myself but sometimes it's worth the effort this video was sponsored by brilliant whether or not you believe that anti-gravitating matter exists it's fun playing around with the idea what you could do with it if it exists and it's really basic physics if you want to freshen up your knowledge about physics or learn something new brilliant is a great place to start brilliant is a website and app that offers interactive courses on a large variety of topics in science and mathematics i love
START_SPONSOR_TOKEN this video was sponsored by brilliant whether or not you believe that anti-gravitating matter exists it's fun playing around with the idea what you could do with it if it exists and it's really basic physics if you want to freshen up your knowledge about physics or learn something new brilliant is a great place to start brilliant is a website and app that offers interactive courses on a large variety of topics in science and mathematics i love END_SPONSOR_TOKEN