The beginning and end of the universe?

[hypervalent_iodine]

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Moderator Note

schmengie,

Stop dragging this thread off topic. I have removed the last lot of posts. If you continue to hijack threads, you will be suspended from posting.

If other members could simply report OT posts, it would be appreciated.

[ajb]

I wasn't trying to hijack any thread.

I think you are trying to hijack this thread again.

 

(The comments below are also for SimonFunnell as well as shmengie)

 

The point is that the Lambda CDM model is an effective theory (not considered fundamental) that has a parameter space that fits just about all of the observations reasonably. As an effective theory it cannot and is not expected to be the final say in cosmology: there is still work to do understanding dark matter, dark energy and so on. However, today just about all cosmologists agree that it fits so well that any 'alternative cosmology' for the very early Universe must quickly evolve into the Lambda CDM in some suitable limits.

 

So, if we want to discuss cosmology then we need a model. As the best fitting model and the minimalistic one is the Lambda CDM model it makes sense that we reply to people's questions within this model. We are all happy to discuss the problems with this model, but without a better model we cannot really be discussing science by simply saying 'Lambda CMB is wrong'. Moreover, most objections that we see on this forum are usually due to misunderstandings from pop-sci analogies or they are philosophical objections. Neither is really enough to start the debate on building better models.

[shmengie]

So, if we want to discuss cosmology then we need a model. As the best fitting model and the minimalistic one is the Lambda CDM model it makes sense that we reply to people's questions within this model. We are all happy to discuss the problems with this model, but without a better model we cannot really be discussing science by simply saying 'Lambda CMB is wrong'. Moreover, most objections that we see on this forum are usually due to misunderstandings from pop-sci analogies or they are philosophical objections. Neither is really enough to start the debate on building better models.

 

If we must discuss LCDM as the best fitting model. We should also point out its the most actively worked model not necessarily the best in any respect because we do not know what all we do not know.

 

LCDM is the most active because it is the most accepted. Its kinda a defacto-standard.

 

IMO GR is the best model, from which many aspects of LCDM is based, ironically they were only taken into consideration because GR happens to be the simplest to date model of time-space-and-gravity for the Universe ever developed by man (Einstein).

 

I've been working to understand it. Why my last post was removed, is a joke, because it was directed to be on topic, not a high slapping I might have made it sound to be. Did prove what I was expecting. There's little room for opinions when the obvious is hidden in plain text.

 

Tho, I guess I don't fit the model of a utopic [latex]\lambda[/latex]pot.

Edited April 5, 2016 by shmengie

[ajb]

We should also point out its the most actively worked model not necessarily the best in any respect because we do not know what all we do not know.

It is the best we have right now. Also we should point out that other variants of the 'big bang' were heavily studied. The Lambda CDM model is now the 'standard model' as it is the simplest model that can be made to fit the data reasonably. This is why it is now so popular with cosmologists.

 

LCDM is the most active because it is the most accepted. Its kinda a defacto-standard.

And why it is the most accepted I state above.

 

IMO GR is the best model, from which many aspects of LCDM is based, ironically they were only taken into consideration because GR happens to be the simplest to date model of time-space-and-gravity for the Universe ever developed by man (Einstein).

Yes GR is the best model we have of gravity today. The Lambda CDM is a relativistic cosmology: general relativity is inherent in this model. Any cosmological model today will have to be based on general relativity as its framework: or something very close like a F( R ) gravity.

 

I do not understand your claims here. They seem confused.

 

 

 

Anyway, there are some theoretical problems that the Lambda CDM model opens. These include, the particle nature of dark matter; the source of dark energy; the cosmological constant problem (also an issue in particle physics); small anomalies in the CMBR; the question of if general relativity holds on the large scale. Every cosmologist knowns of these and many are working on how to address them. Still, today the Lambda CDM model describes the Universe pretty well. What comes next will be exciting and for sure combine even further particle physics and cosmology... and hopefully at some point quantum gravity.

Edited April 5, 2016 by ajb

[hypervalent_iodine]

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Moderator Note

Once again, I have split the last spate of posts into the trash. A reminder to all members to keep this on topic. That means, if someone attempts to re-hijack this thread, please just report it. Replying and thereby continuing to drag a thread off topic is not appreciated.