<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'm curious why they couldn't determine the type of elements that were emitting the light and simply measure the redshift of the actual photons from the event? I guess if you can't isolate the elements, you can't determine a redshift? <br />Posted by michaelmozina</DIV><br /><br />sigh...</p><p>I don't know if you understand how spectra work. Certain elements (and energy states of specific elements) emit and/or absorb EM radiation at specific wavelengths. When they are redshifted by the expansion of the universe, those frequencies are shifted by a certain amount. If you can detect a known pattern of emission/absorbtion shifted by a constant factor you can identify the elements/atoms/molecules/energy states that created them. The ratio between the lines stays the same, and that is what confirms the observations identify certain atoms/molecules/energy states.</p><p>However, if you have no other constraints other than a few lines, there are many possible identifications. If you can detect more lines (and more frequency ratios) then it becomes a much more solid ID. If you only have a few lines, there are many possible interpretations, limited by the accuracy and resolution of the observations. It's tough science some times.</p><p>Believe it or not, the spectra don't stand up and wave little flags saying "I'm Hydrogen I and I'm Neon II"</p><p>It's sometimes real hard science to extract the truth out of raw data. Sometimes it's easy (like of the sun from earth)</p><p>In this particular case (unlike most others) the intepretation is very difficult, so there is more than one answer that can fit the data within the error bars. Hopefully more observations will provide sufficient data to resolve the question.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>