As we know the universe which temperature is 2.7 degree Celsius too cold Is not a small galaxy there are many galaxies beside our milky way also ,So there are other things that we will talk later like the black holes is our main motive to discover about ; the scientist are trying to find the date till today many scientist have given theory but the most accurate is that from my opinion the theory by Einstein and the theory was started to come in his mind because when a team of Cambridge was releasing heat rays or some kind of uv rays then they get the heat signature again so it might be any thing and if you thing I am telling you a lie so go and read the last chapters of black holes and baby universe by Stephen Hawking
