Hey guys!
This is Astronomical Thoughts where I discuss
really cool ways of thinking about astronomy
phenomena.
And today, I'm going to be talking about Olbers'
paradox.
This paradox was named after Heinrich Wilhelm
Olbers and he lived between 1758 - 1840.
And during this time, people use to believe
that the universe was infinite in time and
length.
And Olbers saw a paradox with that.
He said that if the universe is infinite then
there should be infinite number of stars in
our sight when we look up at the night sky
and when he calculated the light coming from
all these stars, it added up to around the
brightness of our sun.
So he concluded that even during night time,
there should be as much light as there is
during the day time, if the universe is infinite
that is.
But we don't see any of this light during
the night.
Hence, the paradox.
Now there are multiple explanations to this
paradox but I'm only going to discuss the
main explanation to this paradox which is
this: Scientists are pretty sure that the
universe started with the big bang and if
so, then the universe cannot be infinite because
the universe had a beginning so it is finite
in size and age, according to the big bang.
Now, during the time Olbers was living, they
didn't know about the big bang theory so you
might think well this solves the paradox.
Olbers thought the universe was infinite but
it's not.
Well, it's not that simple.
If we are going to use the big bang theory
to debunk Olbers' paradox, we need to look
at what predictions the big bang theory is
making and one prediction is that we should
be seeing orange light from the early stages
of the big bang and this light should make
our sky very bright during the night time.
So, are we back to square one?
Well, no.
Actually, we are seeing this orange light
but due to the expansion of the universe,
space is being stretched and so the wavelength
of this orange visible light has increased
to microwave.
And we have detected this microwave light
using microwave telescopes.
And this microwave light is called Cosmic
Microwave Background radiation or CMB.
Ok, so to conclude, universe is not infinite
but Olbers didn't know that and we used the
big bang theory to debunk Olbers' paradox
but the big bang theory also predicts that
our night should be bright and we learned
that it is but in microwave wavelength, not
visible light.
Thanks for watching and take care.
