Rotating Question Curious About Astronomy? Ask an Astronomer

Can we look back far enough in time to see the Big Bang?

As we look at other galaxies we are essentially looking back in time. Can we look back far enough to see the big bang itself? If this is so and c is constant, how did we get here before the light arrived?

It turns out that we cannot see the Big Bang for a "technical" reason. If you think about it, we can use light to look at distant objects because light propagates freely from the matter which emitted it. This was not always the case: when the Universe was less than 100 000 years old, the matter and radiation were so densely packed that light was "coupled" to the matter. This means that light which was emitted when the Universe was less than 100 000 years old couldn't "go anywhere", and hence can't reach us today. Observationally, this means that when we try to look at higher and higher redshifts, we hit a "wall" corresponding to the redshift when the Universe was 100 000 years old. This wall is the cosmic microwave background, or CMB. Look at this topic page for more information for more information about the CMB.

So, we cannot look back to see the Big Bang. And, since the expansion of the Universe has been less than the speed of light since the emission of the CMB, we do not have to worry about the problems you mention.

November 2002, Kristine Spekkens (more by Kristine Spekkens) (Like this Answer)

Still Curious?

Get More 'Curious?' with Our New PODCAST:

Related questions:

More questions about Cosmology and the Big Bang: Previous | Next

How to ask a question:

If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.

Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist

This page has been accessed 51177 times since May 2, 2002.
Last modified: October 18, 2005 6:49:13 PM

Legal questions? See our copyright, disclaimer and privacy policy.
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.

Warning: Your browser is misbehaving! This page might look ugly. (Details)