Astronomy & formulae

thecommander

Bit of an odd question here regarding astronomy.

At what point do scientists stop looking thru telescopes at blackholes/stars/galaxys as a way of understanding the universe and turn to mathematics and formulae on a blackboard.

Silly question I know, and cant probably be explained in a single post but it baffles me as to what relation the numbers have to a physical thing out in space.

Alliandre

Well first of all you can't look through a telescope and see a black hole.

It works in a number of ways, depending on what you're studying. You might want to observe something in particular using the Keck telescope (or HST etc), in which case you put in a proposal for observing time and hope you're approved. If you are, then you go to the relevant observatory and tell the technician what you want. You never actually look through the professional telescopes. It's all CCD imaging and it's the data you're after. Then hopefully you get a few nights of data and you go away for 6 months and analyse it all and discover something cool.

If it's a project that has constant access to it's own telescope, such as OGLE, then there is a continuous stream of data, which is reduced via a reduction pipeline. Often the data reduction is months behind the observations. This is why Kepler has only announced a few planets yet. It takes a while to go through all the data.

As for formulae on blackboards, it's all done via computers. Unless you're trying to work out a certain equation or something (and I'd use a notepad not a blackboard ). Computers are used to solve equations, fit models to theory, get actual information out of the pretty pictures, analyse spectra to find the composition of a star etc etc. You can't tell an awful lot from just looking at the stars and galaxies. A lot of astronomy is done from fitting computer models to the actual data and then hoping the theory behind the model is correct.

It's not a silly question and I can go in to more detail if you want.

thecommander

So its basically gathering data to prove a model, rather than creating a model from the data?

Alliandre

It's a little of both I suppose. A model is created from data, say for example it's just a curve. But on it's own, we have no idea what that means. Therefore the same result is recreated on a computer. Once the computer curve matches the actual curve from the data, we should know what the data means, assuming that all the correct parameters were put into the computer model. Of course, there's always some uncertainty involved and there are often arguements over what computer model will fit the actual data best, and thus which theory is more correct. It's not always graphs, I'm just picking one particular thing.

For example, there's a particular graph that COBE and WMAP etc have that measures the baryonic acoustic oscillations that occur in the Cosmic Microwave Background. Here's a link to the WMAP data that you can play with: http://wmap.gsfc.nasa.gov/resources/camb_tool/index.html

The red line is taken from actual measurements. You can adjust the amount of dark matter, dark energy etc until your curve matches the observed curve. It's in this manner that we can find out what the actual curve means and it can give us information such as the age of the universe. I hope that makes sense.