# B Examples of theoretical proofs overturned by evidence?

#### PeterDonis

Mentor
If I were to make a direct comparison between the H - P singularity theorems and Inflationary theory, Ekpyrotic theory and Steady State theory, that would be incorrect, wouldn't it? The first isn't an empirical theory, while the others are. That would be like comparing oranges and apples, right?
Yes.

if I were to claim that the first must be true, because it is proven, then I'd be making an error. A mathematical proof (even though it relates to the origin of the universe) cannot be taken as legitimately describing the universe in the same way that an empirical does. Is that so?
Yes. As Bertrand Russell famously said, "Mathematics is the subject in which we do not know what we are talking about, nor whether what we are saying is true."

#### Cerenkov

Why do you say "stand or fall"? Mathematical theorems are mathematical theorems. The H-P singularity theorems are still true mathematical theorems even if it turns out that there is nowhere in our actual universe in which their premises are satisfied.

More generally, why do you care about "standing or falling"? What problem are you trying to solve, and why does it matter for that problem whether the singularity theorems "stand or fall"? Math is math and physics is physics; math is a tool used in physics, but the tool and the user are not the same.

Peter,

Please try to see things from my p.o.v. I have no formal training in the sciences and so it's an uphill struggle for me to untangle what you've learned years ago and now understand with little effort. For you these matters seem obvious, but for me they are not. You can easily see the lines of demarcation between math and physics, while I do so with difficulty. You can see what the tool is and who the user is, but I struggle to do so.

Therefore, when I commit errors, go down blind alleys and make mistakes, these are indicators of my lack of knowledge, training and experience. Nothing more. So please cut me some slack.

Why do I care about GR standing or falling? What problem am I trying to solve? Why does it matter to me?

Ahh... if only I were clever enough to be able to understand what the problem even is! The bottom line here is that I'm a passionately-interested amateur who's very much out of his depth, but still grateful to receive your help.

I hope that explains things.

Cerenkov.

#### PeterDonis

Mentor
if only I were clever enough to be able to understand what the problem even is!
In other words, you're asking questions but you don't even know why you're asking them? Isn't that an indication that maybe those aren't questions that need to be asked?

Presumably you had some reason for starting this thread in the first place. What was it?

#### pinball1970

Gold Member
Pop science books are not valid references for PF discussion.
I assumed he published his papers then put out a pop Science book to make some of the ideas accessable to the general reader as Hawking did.
It was more of an invite for someone to explain what the papers were outlining and what the current experimental data has done to support or refute them.

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#### Cerenkov

In other words, you're asking questions but you don't even know why you're asking them? Isn't that an indication that maybe those aren't questions that need to be asked?

Presumably you had some reason for starting this thread in the first place. What was it?
Not exactly, Peter.
I do know why I'm asking them, but if they are improperly worded, then that's down to what I've already mentioned. My inexperience, my lack of training and my lack of knowledge.

Yes, of course that's an indication that these aren't the questions that need to be asked! I've already stated it as plainly as I can that I'm struggling to do this. Hence the need for your guidance.

My reason for starting this thread is exactly this - a burning desire to know just how the H - P theorems work. What they are saying and what they aren't saying. What they can do and what they can't. Where they apply and where they don't. That is why.

As strange as it may seem, it is possible for a non-scientist to be passionately interested in science as a scientist. Here in PF I'm trying to learn about the singularity theorems of Hawking and Penrose. But I'm also just as interested in neutrino experiments like DUNE and the gravitational wave discoveries of LIGO. In due time I'll try asking questions about those experiments. But the H - P theorems come first.

Dogged persistence in the face of difficulty is simply a hallmark of my character. It's who I am. I don't give up. Ever. Just ask the people who play tabletop war games against me. I fight to the last man if need be. I never yield, even in the face of insurmountable odds. It's what I do.

So Peter, I display this same kind of unyielding determination, here in PF.

Thank you.

Cerenkov.

#### PeterDonis

Mentor
I assumed he published his papers then put out a pop Science book to make some of the ideas accessable to the general reader as Hawking did.
And if your assumption is correct, then there will be published peer-reviewed papers by him that can be used as references. That doesn't change the fact that his pop science book is not a valid PF reference.

It was more of an invite for someone to explain what the papers were outlining and what the current experimental data has done to support or refute them.
And if you can reference particular papers, then that is a valid subject for discussion. But his pop science book is still not.

#### pinball1970

Gold Member
And if your assumption is correct, then there will be published peer-reviewed papers by him that can be used as references. That doesn't change the fact that his pop science book is not a valid PF reference.

And if you can reference particular papers, then that is a valid subject for discussion. But his pop science book is still not.
Ok trying to find them. I'll feedback

#### PeterDonis

Mentor
My reason for starting this thread is exactly this - a burning desire to know just how the H - P theorems work. What they are saying and what they aren't saying. What they can do and what they can't. Where they apply and where they don't. That is why.
Then that's what you should have asked in the OP of this thread. And the thread title should have been something like "How do the H-P theorems work" or "What do the H-P theorems say and when do they apply". Basically we've wasted more than 30 posts finding out that what you're actually interested in has nothing to do with the title or OP question of the thread.

Dogged persistence in the face of difficulty is simply a hallmark of my character.
Dogged persistence is fine, but it's not the only skill you need. You also need to be able to ask what you actually want to ask.

Since the title and OP question of this thread are not what you actually wanted to ask, I am closing this thread. If you want to know about the H-P singularity theorems, then you can ask a specific question about those theorems in a new thread. I would strongly recommend thinking carefully about framing a specific question rather than just something like "How do the H-P theorems work?"

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