34student

2 hours ago, Genady said:

Maybe you shouldn't look into youtube videos as representation of scientific thinking?

I don't care about the medium; I care about the content and the source.

30 minutes ago, Genady said:

I think that most physicists think, this IS a valid option. Many think that one day we'll be able to derive Lambda and other numbers which today we need to put in "by hand", from some first principles. So, they are what they are because they cannot be anything else, any other numbers will lead to some inconsistencies.

I just watched another Closer to the Truth about the fine-tuned universe.  In this one, Robert interviews Michio Kaku.  In the beginning, Michio only present 2 options as an explanation of a fine-tuned universe, God or Multiverse 2:55.  He doesn't even seem to want acknowledge the option that I am currently stuck on, but believe it nonetheless.

Then at 4:00, Robert does bring that option.  But they dismiss it quickly as Robert says that it is "less and less like as an alternative".  But I don't understand why it is less and less likely.  Further more, Michio uses terms like "significant" and "special" to describe the universe.  I just do not understand this line of thinking.  

19 hours ago, exchemist said:

I do not think what you say it true.

Most scientists, it seems to me,  don't give a moment's thought to the question and simply accept the values of the fundamental constants are what they are.  So in effect your "so what" option is what they subscribe to, by default.

I think you are making a fuss about nothing, to be honest. 

Then you just haven't looked into this subject close enough.

43 minutes ago, Genady said:

That's right. Why do you expect "there being a problem?"

Let me explain it this way.  Scientists believe we have only one of the three choices I mentioned earlier: God, multiverse and the universe is not fine-tuned.  For me, and others on this thread, there is a very obvious - too obvious - 4th option.  The 4th option is that the universe is fine-tuned for life, so what.  I am trying to understand why they don't think this is an option.

13 minutes ago, Genady said:

You said some time back that "it has to do with the universe existing the way that it does is too improbable".  I think that I didn't make it clear then, so I do now: I don't think that it has to do with the universe being improbable, but rather with it having improbable value of some parameter, e.g. Lambda. I said then that all universes have the same probability to exist, but the values of Lambda don't have the same probability. That's why Lambda is in the picture. I do not compare probabilities of different universes. They are equal. I compare probabilities of having various Lambdas. These are not equal.

But with so many variables that the universe has, then it should not be surprising that some of these variables are less likely.  

I could understand there being a problem if all posible variables were unlikely or something like that.

21 hours ago, Genady said:

The Lambda was what led to the comparison. It was not chosen for comparison. What is your reason for comparison?

Yes I agree in the order of events.  Lambda happened, then 14 billion years later you wanted to give me an example of something that our universe has that most of the others don't.  Then you chose lambda.  These are the order of events.  

9 minutes ago, Genady said:

Sorry, I'm missing something in your argument. I didn't chose anything.

Yes you did. You chose the variable lambda to compare us to other universes.

6 minutes ago, Genady said:

I don't understand this. The question is not about "something", but specifically about our value of Lambda. Relatively small change in this value of Lambda would lead to a universe without planets, stars, galaxies, almost all chemical elements, etc, i.e. without life.

But you chose the unlikely variable.  It may be an important or interesting variable to choose for humans, but it is not important or interesting objectively.

15 minutes ago, Genady said:

If you imagine a probability distribution of different values of Lambda in various universes, then supposedly there are more universes with Lambda many orders of magnitude larger than what we got here. Or, there are more possible initial conditions that lead to the larger Lambda than the ones that lead to such a small Lambda. Each specific universe has the same probability to exist, but by picking a universe at random you get very small probability that it will have our value of Lambda. Vast majority of them will have a much larger value.

But you have chosen something in our universe that is unlikely.  You could have chosen something about our universe that is likely.  Then wouldn't they cancel each other out?

25 minutes ago, Genady said:

I don't see, why it is not. I think so, too. And as I understand, Alan - and many other physicists - think so as well: it just happened so that this universe, either alone or one of many, can and does have life in it. I don't know where the impression of this being an issue came from. I mean, where in the science of physics. Philosophy is a different story, but that would be a different forum.

I *think* it has to do with the universe existing the way that it does is too improbable.  Alan, and many others, think we need to resort to a multiverse so that there can exist the more probable universes too.  But it would seem to me that any universe had an equally likelihood of existing, given the randomness of initial conditions at the big bang - I think.  

2 hours ago, Genady said:

I've seen him interviewing Alan Guth. Guth said about the same that I've described regarding the vacuum energy density. Anyway, being interviewed doesn't mean that they "are submerged in this topic and they believe that there is a problem/issue that needs to be solved." Guth is not and does not. I don't know who is / does.

Here it is: Alan Guth - What Does A Fine-Tuned Universe Mean? - YouTube

 

In the video you posted, right off the bat Robert presents Alan with 3 explanations about how the universe is so fine-tuned and Alan agrees with him.  The 3 choices are God, multiverse and the universe is not so fine-tuned.  An option that makes sense to me is that the universe we have just so happen to have life in it.  But clearly this is not a good option.  So, I know I am missing something, something that must be so obvious that they do not even need to mention it. 

13 minutes ago, Genady said:

Who are they? The only seriously considered related issue that I know of is the value of cosmological constant / vacuum energy density. And this is not because its fitness for life. Rather, the other way around:

if we assume that this number can be different and that it actually is different in different "pocket universes", then the specific value that we observe is what it is simply because most other values don't allow for existence of an observer in those universes.

Here is a quote from Robert Lawrence Kuhn (a neuroscientist himself) who investigates mysteries in science, "How can so many numbers of nature, the constants and relationships of physics, be so spot-on perfect for humans to exist? Beware: there is more than one answer lurking here. Featuring interviews with John Leslie, Steven Weinberg, David Gross, John Polkinghorne, Robin Collins, and Paul Davies.".

Here is the video link if you are interested, 

9 hours ago, erik said:

It is too anthropocentric.

I meant: why is it even considered by scientists as an issue.  I am where you are in that it is too anthropocentric like you say.  But it seems very hard to know their side of the argument.  That is what I want to know.

4 hours ago, Genady said:

A fine-tuned universe is not a problem, but an observation that the universe is very sensitive to a couple dozens of numbers that we put into our fundamental theories "by hand". These numbers are obtained experimentally or observationally. Relatively small changes in their values would lead to big changes in the observable universe.

There are many very smart scientists that are submerged in this topic and they believe that there is a problem/issue that needs to be solved.  I wish I knew what their issue is with a universe that seems to be fine-tuned for life.

2 hours ago, TheVat said:

If you imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in — an interesting hole I find myself in — fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!'

-- Doug Adams

 

Yeah this is where I am at with all of this in that it is just a type of universe that just so happens to have life in it, so what.  But there seems to be another side of this view; I hope to learn what it is.

I don't understand in what sense there is an issue here.

33 minutes ago, MigL said:

If you place your finger about a foot away from your face, and you look at it with one eye closed, you see it in a certain position relative to the background.
If you then close the open eye, and open the other one, you see your finger in a different position relative to the background.
Do you think your finger moved ???
Is it in two places at once ???
Is that a superposition of ststes ???

Or is it simply your viewpoint that has changed ?

But aren't we assuming that length contraction is not just an illusion?  In that case, when you and I say "see it in a different position" doesn't this really mean, "is in a different position"?  

26 minutes ago, Ghideon said:

Why do you speak of only length contraction and never mentioning time dilation in this context?

I do not know what context you are referring to because you cut out only "length contraction".

27 minutes ago, Ghideon said:

Can you support that claim with a reference to relativity? 

Relativity says that length contraction is not just an illusion.  So when a sufficiently fast particle turns Earth into a pancake, then I have to figure that this changes the structure of the universe from what it would have been if there were no such frame of reference from the particle.

33 minutes ago, Ghideon said:

From the point of view of the passengers on the train they, and the train, are not moving. And from the same point of view (the passengers on the train) an object in the trains path will appear to be moving towards the train and strike the train. 

Yes, but the outcomes are the same.  The outcomes are not the same in the muon evidence of length contraction.  Something different happens because of the length contraction than if there were no length contraction, specifically the impact on the Earth's surface vs not impacting it without length contraction.

6 minutes ago, swansont said:

Why not? 

I tried to explain in the following sentences.    

11 minutes ago, swansont said:

The contraction of the length doesn’t affect the “structure of the universe”

As you have acknowledged, length is not a physical object. It’s merely the distance between tow points, which is shorter when there is relative motion.

But the different shape from length contraction causes the muon to interact with the universe in a different way than if there were no length contraction.  Of course the structure of the universe has changed because of length contraction.

15 minutes ago, swansont said:

Tell that to an object in its path.

You are not paying attention to what I am saying.  Your argument about the relativity of kinetic energy of the train is not the same as the relativity of the difference in shape from a length contraction (keep reading because I am about to explain why.).  

The length contraction from muon's frame of reference actually causes something different to happen, such as impacting the Earth's surface when it should have decayed before making it to the surface.  The change in shape actually causes something different to happen than if there were no length contraction from the muon's frame of reference.  But with the kinetic energy of the train versus no kinetic energy from the passengers' point of view, nothing different will happen.  An object in the train's path is still going to get struck, etc.

14 hours ago, swansont said:

True of any relative property. 

Shape is not relative.  It is inherent to the structure of the universe. 

Equating kinetic energy to length contraction as being the same kind of relative property to the universe does not work either. 

We know this because the change in the structure of the universe from length contraction actually causes the muon to interact with the Earth's surface earlier than it should.  But if there were no contraction, it would not interact with the Earth's surface. 

Whereas a train having kinetic energy does not cause something different to happen than the train not having kinetic energy as seen by the passengers.   

11 hours ago, MigL said:

I thought you said you understood relativity ...

Something cannot be relative to itself.
The particle has different positions ( and times ) relative to different observers.
Each observer, in a different frame, sees the particle in a different position ( and at a diferent time ).
That is why frames of reference are so important.

So if each observer sees the same particle in a different position, how is that not a superposition of position?

1 minute ago, swansont said:

They are. 

Yet two different shapes of the same particles exist.

1 hour ago, swansont said:

That’s nonsensical. There is one particle, and “relative to itself” isn’t a thing. “Relative” requires two frames.

Particles should be in the same place that they are in.  If not, I do not know how else to describe it other than a superposition of position.

57 minutes ago, MigL said:

The 'duration' and 'length' of an event, in relativity, is equivalent to the projection on the spatial and temporal axis, of its rest frame ( proper ) length and duration.
This projection is different for different observers, depending on their position on the spatial/temporal axis. IOW, depending on the speed ( and vice versa ).

 

Yes, I am with you on this.  I understand.

57 minutes ago, MigL said:

 

The frame has no physical effect, nor does it change anything directly.
It is simply the point of view of the observer, taking his circumstances into consideration.
It is similar to measuring your shadow in a North facing frame, as opposed to a south facing frame. In the first you will measure your shadow to be very long because the sun is at your back, while in the second, you will be facing the sun , and will see little, or no shadow.

In your example, both universes are identical, they overlap perfectly.   

But when the universes of length contraction overlap, we do not get an exact match.  The positioning is different.  We have the same particles, but they are in different positions relative to themselves.

55 minutes ago, beecee said:

 Space and time, (spacetime) are not physical. You have already agreed to that.

I told you in my last post to you that I agreed that distance is not physical, not spacetime.  Spacetime is clearly physical.

17 minutes ago, swansont said:

A muon being shaped like a worldline is not “well known” and not a true statement.

 

Well then you do not understand fundamental implications of GR.  In GR particles extend through time.

6 minutes ago, beecee said:

Space and time (like length, breadth, and height) are certainly not physical...I thought you agreed with that. Yet they (spacetime) warp, twist, curve in the presence of mass/energy.

 That still doesn't make spacetime ( or space and time) physical.

 

Of course it does.  What more can you ask for than for it to have causal properties, and in a predictable manner yet?

Distance, however, seems nonphysical IMO.  It is like asking if nothing exists.  Well it kind of does but it also doesn't.

25 minutes ago, beecee said:

The warping and curvature of spacetime, by mass/energy, causes light to follow geodesic paths and such phenomena as gravitational lensing.

The interchangebility of space and time.  https://www.physicsoftheuniverse.com/topics_relativity_spacetime.html#:~:text=Thus%2C space and time are,approaching the speed of light.

Yes, I understand that space and time are interchangeable.

3 minutes ago, beecee said:

The warping and curvature of spacetime, by mass/energy, causes light to follow geodesic paths and such phenomena as gravitational lensing.

Cause and effect are very strong indicators that something is physical.

You mention spacetime.  Matter causes a spacetime curvature, so we are half way there.  And, spacetime curvature also affects matter.  It has a cause and it has an effect; it is physical.

36 minutes ago, Phi for All said:

So I'll mention (AGAIN) that you're wrong about length contraction not being observer dependent.

Yes, it would definitely appear that length contraction is observer dependent.  I know that there is a lot of evidence and theory to support this claim.  I know this.

However, when I take GR further, I see that observation and frames of reference don't really exist in any physical way.  There doesn't seem to be a direct mechanical explanation for how an observer or frame of reference causes this length contraction.

Even worse, frames of reference do no even seem to physically exist in GR even though we use them and need them to support the theory of GR.

4 minutes ago, MigL said:

Just about everything you've said.
And people have been telling you for two pages already, but you simply ignore them and go on.
That's no way to learn anything ...

I am always open to learning.  Contrary to what you are saying, I understand the basics of GR.  I learnt about SR in university 10 years ago, and I have been reading about it ever since.  I would really really like to know what I have said about GR that is wrong on this thread.