<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I recently posted a question about the legitimacy String Theory being called a theory. I also only just made a regrettably smart-alecky comment about the Big Bang theory also not being a real one. However, I'm doubting myself somewhat now. Isn't there some observable proof of the big bang such as the way matter is moving away from a common centroid? A colleague of mine did say there were some "problems" with it being a theory- although he didn't specify what those might be. Could someone clear me up or at least add better conjecture than my own? <br /> Posted by Anglocowboy</DIV></p><p>String theory, using a 'by the book' definition is not a true scientific theory because it can not be tested through experimentation or observation and therefor can not be falsified. I wouldn't suggest telling a string theorist that their theory is not science, even though they would likely agree with you. At least if you want to get on their good side, I wouldn't suggest it.<br /><br />A theory is never really proven or factual in the dictionary sense of the term. A good theory is supported by evidence that has yet to be refuted and through a theory, predictions should be able to be made. I always find that using the word 'proof' is a bit misleading. Proof in on a more personal level. I can prove something to you with crappy evidence. However, that doesn't make it valid.<br /><br />Another important factor in being a good scientific theory is that it has to be consistent with other theories. One thing to keep in mind is that theories are almost never complete and never considered as a fact. Despite how well General Relativity and Quantum Mechanics describe their respective realms, they are not complete and have measurable limits. They don't necessarily conflict with each other, but they're not consistent when scaled up or down into the others realm. A quantum theory of gravity is now and has been quite the active field of study for nearly 100 years.<br /><br />In cosmology, theories are quite difficult to reconcile. Often, ideas are highly speculative. Trying to figure out the origin of the universe is no easy task. Explaining how it came to its current state is equally difficult. One of the first things to remember about the Big Bang Theory is that it is not a description of the origin of the universe. It is built to describe the evolution of the universe.<br /><br />The Big Bang Theory is heavily reliant on mathematical models and remote sensing observation that require interpretation. It's pretty difficult to test in the lab. Nevertheless, the BBT is still a highly supported by an overwhelming amount of evidence. A few of the more solid pieces of the puzzle is the homogeneity over the largest scales, the Cosmic Microwave Background radiation (CMB), the Hubble constant coupled with redshift and type Ia supernova time dilation and the amount of light elements present described through nucleosynthesis.<br /><br />Do these "prove" the big bang? Of course not, but there are no better theories to date. There are no better models that present a consistent description of what we observe. Does the Big Bang have what you might consider issues? Certainly. However, these issues don't falsify the theory. Are there other theories out there? Sure, but they are generally not consistent with observation, nor are they consistent with other theories and models. Are their questionable, debatable theories and models within the BBT? Definitely. No theories are ever really complete. Especially concerning cosmology and astrophysics. There just too many damned questions!!! <br /><br />The BBT is not perfect, nor is it complete. It doesn't claim to have all the answers, nor does it claim to be fact. It is simply the best we've got at the moment and there is no reason to not continue with it. Folks are welcome to investigate the petabytes worth of data collected and come up with something better. Folk have tried and folks have failed. Folks are still trying and still failing. Maybe there will be a paradigm shift someday and I hope I'm around to see it if there is one. That would be truly exciting. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>