Is Paul Steinhardt's Statement "Rather Pathetic"? Why?

[Fuzzy Logic]

It's not nearly so bad as that. We may not know the requirements for life in detail, but it is very easy to place limits based upon general, overall requirements. For example, if you want to have life, you are going to need structure formation. That is, you need galaxies. And simple limits like this are enough to make pretty powerful statements about the possible values of some parameters that any observer can potentially measure.

It is interesting how fickle life seems to be but it doesn't matter how many times you roll the dice, the odds of rolling a 1 are always the same. You can maximize chance with iterations but not odds. It is just as likely that life emerged on the first iteration or the trillionth.

All of nature is uncanny how it manages to work, not just life. I don't think that uncanny is evidence of anything.

 

[Chalnoth]

It is interesting how fickle life seems to be but it doesn't matter how many times you roll the dice, the odds of rolling a 1 are always the same. You can maximize chance with iterations but not odds. It is just as likely that life emerged on the first iteration or the trillionth.

All of nature is uncanny how it manages to work, not just life. I don't think that uncanny is evidence of anything.

What are you trying to say here? Because as near as I can tell it has nothing to do with anthropic arguments. Anthropic arguments are, at their heart, arguments about what aspects of nature we have a right to be surprised about. If a certain aspect of nature seems, on its face, highly unlikely, but it turns out that something like it is required for life to exist, then we don't have any right to be surprised to see it. The cosmological constant is a good example here. Sure, the number $10^{-120}$ seems fantastically small, but it can't possibly have been much bigger and still allowed the existence of galaxies. Because a cosmological constant this small is required for us to exist, we can't, by rights, be surprised about it.

 

[MathematicalPhysicist]

I am not sure, my message was really understood.

How do you define "universe"?

If it's:"All existing matter and space considered as a whole; the cosmos."

Then multiverse=universe, multiverse is just another name for "all that exists".

If on the other hand you say that a universe is all that is made of the same matter as we are, then there might be other universes with different type of matter different than ours.

But it depends on your definition.

 

[Chalnoth]

I am not sure, my message was really understood.

How do you define "universe"?

If it's:"All existing matter and space considered as a whole; the cosmos."

Then multiverse=universe, multiverse is just another name for "all that exists".

If on the other hand you say that a universe is all that is made of the same matter as we are, then there might be other universes with different type of matter different than ours.

But it depends on your definition.

The only way in which it's an interesting topic of discussion is in regard to the low-energy laws of physics varying from place to place within the universe.

 

[Fuzzy Logic]

Ok in that sense sure, but do we really need a principle to define it? That is just elementary deduction. "I think, therefore I am"

I was referring to the anthropic principle being a justification for a multiverse.
As far as I understand, there is no evidence that any of the fundamental conditions must or even could change, only predictions.

 

[Chalnoth]

Ok in that sense sure, but do we really need a principle to define it? That is just elementary deduction. "I think, therefore I am"

The fact that so many people argue so vociferously against it seems to indicate that yes, yes we do.

I was referring to the anthropic principle being a justification for a multiverse.

I don't think that's an entirely correct way of thinking about it. Rather, as I said earlier, the anthropic principle must be taken into account when considering any law for how new regions of space time are born, or how the low-energy laws of physics might vary.

As far as I understand, there is no evidence that any of the fundamental conditions must or even could change, only predictions.

Any spontaneous symmetry breaking event causes a change in the low-energy laws of physics. The electro-weak symmetry breaking is one we know of. There are probably many more.

 

[marcus]

The only way in which it's an interesting topic of discussion is in regard to the low-energy laws of physics varying from place to place within the universe.

The way I think of it can connect with this. I think of the universe as the unique whole of nature with a unique set of fundamental laws.

Spontaneous symmetry-breaking may have resulted in regional variation in some constants that emerge at lower energy. I think that is extremely interesting and I think it is something we humans may be able to study and understand.

At present I don't see any compelling reason to involve multiple big bangs in our model of the big bang---the start of expansion. Pending evidence to the contrary I expect one start of expansion, operating under one set of fundamental highenergy laws of physics will probably fit the data.

It would be quite interesting if we got some evidence of other big bangs having happened, of course. But absent such evidence *shrug*.

So my view is similar to the one expressed in post #1---the reductionist program is on track, no need to give up on the program of finding ever deeper explanations for what we see in terms of one universe, one start of expansion, one set of fundamental physics laws.

 

[Chalnoth]

At present I don't see any compelling reason to involve multiple big bangs in our model of the big bang---the start of expansion. Pending evidence to the contrary I expect one start of expansion, operating under one set of fundamental highenergy laws of physics will probably fit the data.

Well, it kinda has to. But that same model may unambiguously predict other bangs, other low-energy laws of physics (our current model already predicts other low-energy laws of physics...and other bangs are the natural expectation of any model that produces at least one).

Now, I don't think there is any conceivable way that we will ever be able to obtain direct evidence of universes with different fundamental laws. Though I do think it may be interesting to think about the possibility.

 

[marcus]

Since we just turned a page, I'll recall the post of mine (#112) you were responding to just now

==quote post #112==

The only way in which it's an interesting topic of discussion is in regard to the low-energy laws of physics varying from place to place within the universe.

The way I think of it can connect with this. I think of the universe as the unique whole of nature with a unique set of fundamental laws.

Spontaneous symmetry-breaking may have resulted in regional variation in some constants that emerge at lower energy. I think that is extremely interesting and I think it is something we humans may be able to study and understand.

At present I don't see any compelling reason to involve multiple big bangs in our model of the big bang---the start of expansion. Pending evidence to the contrary I expect one start of expansion, operating under one set of fundamental highenergy laws of physics will probably fit the data.

It would be quite interesting if we got some evidence of other big bangs having happened, of course. But absent such evidence *shrug*.

So my view is similar to the one expressed in post #1---the reductionist program is on track, no need to give up on the program of finding ever deeper explanations for what we see in terms of one universe, one start of expansion, one set of fundamental physics laws.

==endquote==

Then continuing the discussion with your post #113, which think was mainly in response to what I just highlighted blue:

Well, it kinda has to. But that same model may unambiguously predict other bangs, other low-energy laws of physics (our current model already predicts other low-energy laws of physics...and other bangs are the natural expectation of any model that produces at least one).

Now, I don't think there is any conceivable way that we will ever be able to obtain direct evidence of universes with different fundamental laws. Though I do think it may be interesting to think about the possibility.

That seems pretty reasonable to me.

 

[Radrook]

I understood Hawking to mean that the universe is as it is because we can't help but perceive it that way because of what we are-human.