Why is dark energy/matter better than a new theory?

[kenewbie]

If this can be explained in a way that I can understand, I would appreciate it.

Why does one believe that there are things like dark energy and dark matter which skew results from observation away from the predicted results, rather than assume that the predictions are incomplete?

The first thought should obviously be "hmm, guess we have an incomplete view of gravity". But since people in the know rather concludes that there are hereto unobserved matter and energy instead, there is probably a very good reason for this?

k

 

[Teeril]

And recently read that the estimate mass for even the milky way was off by 50%, makes me wonder about the same thing.

 

[turbo]

And recently read that the estimate mass for even the milky way was off by 50%, makes me wonder about the same thing.

About this recent development - it is very difficult for us to accurately measure some basic qualities of our galaxy simply because we are embedded in it.

Looking at other galaxies, we can measure their rotation curves, luminosities, etc, and infer a mass for them, though there are lots of assumptions that play into these estimates. It's very hard to make comparable measurements from a location inside the galaxy under scrutiny.

 

[Hunterbender]

Well, physicists are working to incorporate Dark Matter and Dark Energy with the current models. Those theories receive less hits than string theories and others because there are less hype about them.

A recent paper I read was about a special case model that incorporate some elements of Dark Energy/Dark Matter with a modified GR. I have heard that some particle physicists believe that Dark Matter is just a side effect of unknown particles. There are hundreds of theories, the only problem is: which of these/combination is the right theory.

 

[Steely Dan]

I think it's worth pointing out that dark energy is not really a "theory;" it's more like, the scientific community admitting that it doesn't know what's going on, and saying there needs to be something out there that we can't see in order for our models to make sense.

I think the crux of the dilemma is that it's certainly possible we have flawed observations or predictions and that an extension of the Standard Model would answer some questions; but we're talking about things on a macroscopic scale here. Things violate Newtonian models drastically, more so than a few missed observations would explain. Some people have ventured the idea that Newtonian mechanics is simply incorrect on a large scale, but this isn't something a lot of people enjoy considering without any justification for it. So as long as you accept that Newton's theories of gravity were accept to some decent order of approximation, that's why the idea of dark dark matter is acceptable.