deletions | additions       diff --git a/The_difference_between_the_two__.tex b/The_difference_between_the_two__.tex  index e7166cc..8b37186 100644  --- a/The_difference_between_the_two__.tex  +++ b/The_difference_between_the_two__.tex 
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The difference between the two curves is known as the galaxy rotation problem. It means that either Newton's laws of gravitation are incorrect, or that there is some unobservable force acting within the galaxy leading to the observed effects. There are several proposed solutions to this, with the most widely accepted one being the presence of dark matter that is not mainly distributed in the centre of the galaxy, instead forming a dark matter halo.   \subsection{Measurement of Galaxy Rotation Curves}  The difference between Original observation on  thetwo curves is known as the galaxy  rotation problem. It means that either Newton's laws rates of galaxies was pioneered by Vera Rubin in the 1960’s and 70’s. She inferred the existence  of gravitation are incorrect, or dark matter by calculating  that galaxies would rip themselves apart at current speeds, unless  there is some unobservable was an unseen  force acting within the galaxy, leading holding them together. A spectrograph was used  to measure  the observed effects. There are several proposed solutions to this, with rotation of  the most widely accepted one being galaxies, by looking at  the presence redshift  ofdark matter, that is not mainly distributed in  the centre of stars. Whilst doing this,  the galaxy, instead forming a dark matter halo. redshift due to expansion had to be taken into account.