Complete these sentences by matching the phrases below. When light waves are emitted by a moving source scientist can measure:
?
Doppler affect
Scientists smash
together tiny bits
of matter using:
?
cosmic microwave
background radiation.
Scientists
extrapolate
backwards in
time to derive:
?
particle accelerators.
The extremely
low temperature
of outer space
can be explained
as:
?
the Big Bang theory.