COSMOLOGY:

Q: What is Cosmology?

A: Cosmology is the study of the Universe as a whole. As cosmologists we try to  uncover and map the evolution of the Universe from its beginning through to the present and to determine what may happen to the Universe in the future. We also try to determine what the Universe is made of, and how the material that makes up the Universe is distributed.

Q: What is dark energy?

A: The short answer is no one knows! However even though we do not know what dark energy is we do know some of its properties. Dark energy is the name given to a phenomenon that is causing the expansion of the Universe to accelerate. There are many theoretical explanations for what dark energy could be, for good reviews see Peebles & Ratra, 2003 or Copeland, Sami & Tsujikawa, 2006. The main contenders are an extra gravitational constant known as the “cosmological  constant”, in addition to Newtons constant, that causes an acceleration; an extra cosmological fluid with negative pressure - this is what is most commonly meant when people refer to “dark energy”; or the acceleration could be due to a modification of gravity - that means gravity could actually be more complicated than general relativity and that the extra complexity causes an acceleration.

ICOSMO:

Q: Why is iCosmo written in IDL/ What is IDL?

A: IDL is the Interactive Data Language provided by ITT Industries. It is a very common programming language for scientists and engineers because of its ease of use, user-friendly syntax and compiling and the vast suite of libraries and graphical packages available. It is for these reasons that we choose IDL as the language in which to write iCosmo.

INTERACTIVE WEBPAGE:

Q: How can I find out what constraints on dark energy parameters my experiment will achieve?

A: If you are planning a lensing, bao or supernovae survey you can use the online interactive tool available here. You should then select FIsher matrices on the first page of the Interactive pages and fill in the specific experiment you have in mind by selecting “Custom” on step 2. Alternatively you can select to download the iCosmo source code linked from here.

Q: How do I download a postscript version of the plot I have made?

A: The plots on screen are in gif format, to download a postscript simply click on the plot. In most browsers (internet explorer, firefox, opera) this will then prompt you to either save or open a postscript version of the plot. In some other browsers, for example Safari the postscript may be opened automatically in-screen, you can then save by clicking file and “save as”.

Q: I wish a particular survey option was available/ I wish I could change this parameter.

A: If we have not provided the online option you require you can download the source code from the Tools page.

Q: The webpage looks very odd/ the text looks wrong / the graphs looks wrong.

A: We have tested the webpage in all of the most up-to-date browsers. We suggest that you upgrade your browser or, if you are using an old browser type then you should change to a more modern browser. Not only will a more modern browser enable you to view webpages such as icosmo.org but it will also be more secure. The browsers we recommend are Firefox (for all platforms), Safari (Mac OSX and Windows), Opera (all platforms), IceWeasel (linux).

Here we will endeavor to answer some of your questions about the Tools and Resources we provide here. We are happy to help in any way and if you cannot find the information you need in the help pages provided please email help@icosmo.org.