Meaning of 'by a factor of' in the sentence

[eng7]

The invisible matter in the universe needs to exceed the luminous matter in density by a factor of roughly 70.
I was reading an article where I found this line and could not understand the meaning.

 

[Rover_KE]

Welcome to the forum, eng7.

Please name the source and author of any text you quote.

 

[Tarheel]

That surprises me. I thought it was more like 3-1, but definitely not 70-1.

 

[Raymott]

It means that the density of the invisible matter is seventy times the density of the luminous matter.
Density (invisible matter) = Density (luminous matter) x 70.
But this could mean various things. Does it refer to the total amount, or the comparative density of an equal amount (volume or mass) of invisible matter and luminous matter?

It's not that simple.
https://en.wikipedia.org/wiki/Dark_matter

[Not a Physicist]

 

[jutfrank]

I assume it refers to the total amount as it sound like they're talking about inflation of the Universe. Of course, we'd need to read the article to be sure.