Professor Brian Cox Official Merchandise.
The variation of the scale factor with time. The white curve is our Universe, i.e. 30% matter and 70% dark energy. The red curve is the same but with no dark energy, and the blue is for a universe containing 100% matter. The green is for a universe with no dark energy and a matter density 10 times the critical density - as can be seen, it is a universe that ends with a Big Crunch.
Size Chest (to fit)
S - 34/36", M - 38/40", L - 42/44", XL - 46/48", 2XL - 50/52"
S - 10, M - 12, L - 14, XL - 16, 2XL - 18