Why is a fine-tuned universe a problem?

[34student]

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.

[Genady]

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

[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.

[Genady]

Why then wouldn't you write to these scientists and ask them directly for the missing explanations?

BTW, here is what Neil deGrasse Tyson had to say about how fine the universe is tuned for life. Spoiler: "stupid design."

 

Edited February 13, 2022 by Genady

[erik]

13 hours ago, Genady said:

 

Excellent video which sums up the futility of finetunists.

if you could get teleported to a random spot in the universe, the chance for you to die instantly on arrival would be 99,999999999...% and even if you added a sextillion of 9 after the comma you still would be far from how ridiculous your chance to survive is

Even if you got spawned on a random spot of the planet earth you'd instantly burn to a crisp under the surface 99,99999999......% of the time.

 

By the way all that fine tuning rubbish which is not part of science (I can't stress it enough) comes from string theorists, and was used as a way to promote the multiverse, because some believed the multiverse was a strong prediction of the string theory.

All of that nonsense was developed long before the string theory was proven wrong through experimentation at the LHC. I am not really surprised that over a decade later, medias still push that thing.

 

[Airbrush]

If anyone understands these 6 constants, please summarize them for us.  I think Michio Kaku said the apparent fine-tuning suggests a multiverse of universes with all the wrong parameters, but OUR universe is the lucky one!

Fine-tuned universe - Wikipedia

"Martin Rees formulates the fine-tuning of the universe in terms of the following six dimensionless physical constants.^[2][17]

• N, the ratio of the electromagnetic force to the gravitational force between a pair of protons, is approximately 10³⁶. According to Rees, if it were significantly smaller, only a small and short-lived universe could exist.^[17]
• Epsilon (ε), a measure of the nuclear efficiency of fusion from hydrogen to helium, is 0.007: when four nucleons fuse into helium, 0.007 (0.7%) of their mass is converted to energy. The value of ε is in part determined by the strength of the strong nuclear force.^[18] If ε were 0.006, a proton could not bond to a neutron, and only hydrogen could exist, and complex chemistry would be impossible. According to Rees, if it were above 0.008, no hydrogen would exist, as all the hydrogen would have been fused shortly after the Big Bang. Other physicists disagree, calculating that substantial hydrogen remains as long as the strong force coupling constant increases by less than about 50%.^[15][17]
• Omega (Ω), commonly known as the density parameter, is the relative importance of gravity and expansion energy in the universe. It is the ratio of the mass density of the universe to the "critical density" and is approximately 1. If gravity were too strong compared with dark energy and the initial metric expansion, the universe would have collapsed before life could have evolved. If gravity were too weak, no stars would have formed.^[17][19]
• Lambda (Λ), commonly known as the cosmological constant, describes the ratio of the density of dark energy to the critical energy density of the universe, given certain reasonable assumptions such as that dark energy density is a constant. In terms of Planck units, and as a natural dimensionless value, Λ is on the order of 10⁻¹²².^[20] This is so small that it has no significant effect on cosmic structures that are smaller than a billion light-years across. A slightly larger value of the cosmological constant would have caused space to expand rapidly enough that stars and other astronomical structures would not be able to form.^[17][21]
• Q, the ratio of the gravitational energy required to pull a large galaxy apart to the energy equivalent of its mass, is around 10⁻⁵. If it is too small, no stars can form. If it is too large, no stars can survive because the universe is too violent, according to Rees.^[17]
• D, the number of spatial dimensions in spacetime, is 3. Rees claims that life could not exist if there were 2 or 4 dimensions of spacetime nor if the number of time dimensions in spacetime were anything other than 1.^[17] Rees argues this does not preclude the existence of ten-dimensional strings.^[2]

Fine-tuned universe - Wikipedia

Edited February 28, 2022 by Airbrush

[erik]

Quote

that the observed values are, for some reason, improbable.^[1]

The source given to claim that the constants are improbable is not a scientific paper but a philosophical paper. Which makes sense since the whole idea is nonscientific. The science of probabilities requires multiple occurrences and in the case of the universe as a whole, there is only one occurrence, so you can not make any valid scientific claim regarding the probability of it constants.

Honestly this whole discussion should be moved to the philosophy or theology forums because there isn't any scientific background to back it up at this time.

[MigL]

For the OP to make sense, one must first establish that the universe is 'fine tuned'.

No such thing has been established, so it is a bit presumptuous to call it a problem.

[erik]

String theorists truly have hurt science.

I wish I could talk to one of them right now and tell them "hey look at what you did with your rubbish" even a decade after your theory was proven wrong we still get people breaking our balls with your fine tuned rubbish because all they see through their bias is "omg science proved god".

[Genady]

10 hours ago, erik said:

String theorists truly have hurt science.

I wish I could talk to one of them right now and tell them "hey look at what you did with your rubbish" even a decade after your theory was proven wrong we still get people breaking our balls with your fine tuned rubbish because all they see through their bias is "omg science proved god".

I don't have any attachment to the string theory. Just curious, what do you refer to in "a decade after [it] was proven wrong"? The LHC experiments?

[erik]

1 hour ago, Genady said:

I don't have any attachment to the string theory. Just curious, what do you refer to in "a decade after [it] was proven wrong"? The LHC experiments?

string theory originally predicted sparticles to exist at an energy level lower than the higgs boson's, we detected the higgs boson but we didn't detect any sparticle

string theorists have ever since changed their theory to make sparticles pop up at higher energy levels, but at that point it died as a scientific theory since it was no longer falsifiable

furthermore the recent observations about the neutron stars fusion once again proved the string theory predictions wrong, the event GW170817 showed high consistency between GW and EMW, whereas string theory claims there are hidden dimensions where only gravity can go, which should have resulted in inconsistencies between GW and EMW

 

[Genady]

1 hour ago, erik said:

string theory originally predicted sparticles to exist at an energy level lower than the higgs boson's, we detected the higgs boson but we didn't detect any sparticle

string theorists have ever since changed their theory to make sparticles pop up at higher energy levels, but at that point it died as a scientific theory since it was no longer falsifiable

furthermore the recent observations about the neutron stars fusion once again proved the string theory predictions wrong, the event GW170817 showed high consistency between GW and EMW, whereas string theory claims there are hidden dimensions where only gravity can go, which should have resulted in inconsistencies between GW and EMW

 

AFAIK sparticles are predicted by SUSY rather than string theory, aren't they?

[joigus]

48 minutes ago, Genady said:

AFAIK sparticles are predicted by SUSY rather than string theory, aren't they?

When people say "string theory" what they really mean is "superstring theory" or "M theory" with SS. A theory of strings without supersymmetry is a non-starter.

One of the reasons for this is that you need the fermionic diagrams to correct for the uncontrollable bosonic diagrams, to remove the fine tuning in the Higgs mass.

The other is that the best-behaved QFTs are those with supersymmetry. They can be exactly solved or perturbatively convergent.

 

[Genady]

2 minutes ago, joigus said:

When people say "string theory" what they really mean is "superstring theory" or "M theory" with SS. A theory of strings without supersymmetry is a non-starter.

One of the reasons for this is that you need the fermionic diagrams to correct for the uncontrollable bosonic diagrams, to remove the fine tuning in the Higgs mass.

The other is that the best-behaved QFTs are those with supersymmetry. They can be exactly solved or perturbatively convergent.

 

OK, there is no string theory without SUSY. Is there SUSY without string theory? If so, does it predict sparticles independently of the string theory?

[MigL]

Supersymmetry was also proposed as a way to get rid of all the excess energy of the vacuum predicted by QFT, by destructively interfering all the contributions by regular particles with those of ssparticles.
This would have effectively made vacuum energy equal to zero, which also cannot be right as we have a very good approximation of the vacuum energy required for expansion, about the order of 10^-8 ergs.
And since QFT  ( with just regular particles and a Planck cutoff ) predicts a vacuum energy of 10¹¹² ergs, we have a vacuum catastrophy of 120 orders of magnitude.

Edited March 1, 2022 by MigL

[joigus]

3 hours ago, Genady said:

Is there SUSY without string theory?

Yes. The ambitious (not toy models, like supersymmetric quantum mechanics, etc.) are called supersymmetric extensions of the standard model. There are several of those, depending on the number of so-called central charges. The simplest is known as minimal SS extension of the SM.

[Genady]

4 minutes ago, joigus said:

Yes. The ambitious (not toy models, like supersymmetric quantum mechanics, etc.) are called supersymmetric extensions of the standard model. There are several of those, depending on the number of so-called central charges. The simplest is known as minimal SS extension of the SM.

Hence, if somebody (e.g. @eric in a post above) claims that the fact of not detecting sparticles in LHC refutes string theory, this claim is equally valid to all SS theories, not only the string theory? Or, other SS theories predict much heavier sparticles to begin with?

[joigus]

1 hour ago, Genady said:

Hence, if somebody (e.g. @eric in a post above) claims that the fact of not detecting sparticles in LHC refutes string theory, this claim is equally valid to all SS theories, not only the string theory? Or, other SS theories predict much heavier sparticles to begin with?

I don't think one can say that not having found squarks or photinos in LHC does away with M theory for good. There's a mixed blessing in superstring theory, which is: There's so much freedom in the theory that it's very difficult to rule it out completely --I think--, almost as much as getting concrete predictions from it.

As to supersymmetry, my comment is: High-mass predictions of superpartners are based on masses arising from spontaneous symmetry breaking. That's the only game in town now. But, what if there are other ways for a symmetry to be hidden?

Supersymmetry is a very compelling idea. It's not just about superpartners. I think it goes deeper. It's about symmetries of space-time and internal symmetries. It relates both. Very compelling. Maybe we need to understand quantum mechanics better in order to see what it's telling us.

I'm not saying it must be pushed forward at all costs, but I don't think we're done with trying it out just yet.

I think I can argue in favour of SS a little more, but not now. 😫

[MigL]

Would like to hear those arguments, Joigus.
When you have time, of course.

[Markus Hanke]

On 2/13/2022 at 11:08 AM, erik said:

The idea that the constants could have been different is not part of science, it can not be tested, it can not be falsified, it predicts nothing. It is just a "what if" fantasy.

I agree that the question as to whether they could have been different cannot be scientifically tested, at least not based on current knowledge.

However, asking if at least some constants were different in the past is something that can be done - for example using natural fission reactors.

Of course there’s some conceptual overlap between the above.

[joigus]

On 3/2/2022 at 10:14 PM, MigL said:

Would like to hear those arguments, Joigus.
When you have time, of course.

Ah, I missed this, @MigL. I'm sorry. Let me get back to you later. It's based on some musings by Leonard Susskind. During his lectures on supersymmetry, he laments that SUSY probably is telling us something very deep, but we still don't know what it is. I'm quoting him almost literally.

Essentially it rests on the (mathematical) fact that the SUSY generators, that exchange boson for fermion, can be arranged in a way that produces space-time translations.

Now that could be just a mathematical mirage, but it seems very profound. Another one is that, when you put superspace variables (anticommuting complex coordinates) together with space-time, the Lagrangians of relativistic quantum field theory appear as if by (mathematical) magic. That's what I mean by "really compelling."

Now, I think you know me enough to know that I don't easily fall for 'big' new ideas that have to do with forcing the mathematics. I'm convinced that the way to go is to look at the mathematical form that we know to be right, while trying to interpret it in a way that opens the way to an extrapolation.

I'm not sure I'm explaining myself very well. Maybe tomorrow.

(Famous last words.)

 

[MigL]

9 minutes ago, joigus said:

I don't easily fall for 'big' new ideas

Supersymmetry is now fairly old.
( it was about 10 yrs old, when I first read about it in the 80s )

 

11 minutes ago, joigus said:

the way to go is to look at the mathematical form that we know to be right,

That is what happened with Sstring/M theory.
Unfortunately, in these areas, theory has vastly outpaced observational capabilities.

Sometimes beautiful math isn't enough.
( but you insights are instructional and always valued )

[joigus]

1 minute ago, MigL said:

Supersymmetry is now fairly old.
( it was about 10 yrs old, when I first read about it in the 80s )

 Right. The emphasis was meant on the 'big.'

There was a time when we were new too, remember?

It's been knocking at our door for so many decades that it still sounds new.

You could say it's the future of physics, it's always been, and it always will be.

[beecee]

1 hour ago, MigL said:

Unfortunately, in these areas, theory has vastly outpaced observational capabilities.

Yeah, I have heard that mentioned before. Which prompts the question...are we at the limits of our observational data and capabilities? How much more would we have been able to observe with the cancelled, much larger SSC or "Superconducting Super Collider" Could the construction of the SSC ever be recommenced? 

Edited March 10, 2022 by beecee

[studiot]

A couple of brief comments about constants.

Firstly there are not as many independent constants as some in this thread seem to think.

(Welcome back genady )

On 2/11/2022 at 12:48 PM, 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.

The SI scientific system which defines all scientific measurements, is based on 7 base quantities and 7 universal constants

Quote

https://www.bipm.org/en/measurement-units

From 20 May 2019 all SI units are defined in terms of constants that describe the natural world. This assures the future stability of the SI and opens the opportunity for the use of new technologies, including quantum technologies, to implement the definitions.

So sure there are lots of more convenient constant and quantities for all and sundry, but they can all be related back to these 7 + 7.

Secondly I would put it more strongly than Markus +1

On 3/3/2022 at 1:39 AM, Markus Hanke said:

I agree that the question as to whether they could have been different cannot be scientifically tested, at least not based on current knowledge.

However, asking if at least some constants were different in the past is something that can be done - for example using natural fission reactors.

Of course there’s some conceptual overlap between the above.

I have always understood that astronomers knew that the further away we observed, the further back in time the light we observe came from.
As a result they have spent decades seeking changes to spectroscopic observations that could only be explained by changes to these constants in an earlier age.
As far as i know, no such changes have ever been observed.
That is a major task of the Hubble, James Webb and SKA telescopes. 

SKA:      https://www.bbc.co.uk/news/science-environment-63836496

Thirdly I agee with MigL +1

On 2/28/2022 at 4:47 PM, MigL said:

For the OP to make sense, one must first establish that the universe is 'fine tuned'.

No such thing has been established, so it is a bit presumptuous to call it a problem.

This should have been established on page 1 of this thread.