Oh, and in case you didn't notice: *space must have an edge*. If it was infinite, it couldn't expand.

Translation : I have

*no* idea about topology or geometry, the underlying principles of general relativity or just 'spatial structures' so I'm going to go with my gut instinct, which has no experience of any detailed mathematics or physics beyond high school level. After all,

*I'm John Duffield*.

Just another example of how your lack of experience with concepts beyond everyday experience

*hinders* you, yet you don't realise it. You've previously waxed lyrical about inflation, curvature and cosmology and now, as then, you show how little you understand. MarkM125 has given a quick pointer at the relevant bit of cosmology, namely the length scale factor in the FRW metric. Funny how the counter example to your claim was

*the central thing in cosmology*, something which you've pretended to understand in previous discussions but once again illustrate you do not.

Seriously John, you could open your mind to so much more if you just accepted

*you* aren't the font of all understanding when it comes to physics. Electromagnetism, cosmology, string theory, quantum mechanics, these are things you've claimed to have insight into which no one else has had, yet you demonstrably have no quantitative understanding and you show time and again you don't even have qualitative understanding of even basic principles.

But the stress-energy tensor does have its pressure diagonal.

Given you cannot do any calculus or linear algebra you obviously cannot do any of the tensor calculus which is used to define said tensor. Would you care to explain how you have insight into a mathematical construct when you cannot do said mathematics?

No doubt you'll ignore me, seeing as the answer would require you to admit you're just BS'ing.

Because a gravitational field is just an energy-pressure gradient in space, of space. And if you have no gradient you've still got pressure. In space, of space, and pressure x volume = energy, so at the fundamental level, *space and energy are the same thing*.

Slow down there, I couldn't keep up with all the quantitative detail. No, sorry, I meant

*vapid arm waving*.

Preaching about things you only pretend to understand? You're an example for everyone John. Shame it is the wrong kind of example, one of dishonesty.

Ah, don't you just love cosmology?

Yes, which is why I think your actions are somewhat detestable, pretending to understand the quantitative details, ie tensors, of a physics domain you have no actual experience of beyond pop science books/magazines/websites. The above example of the FRW length scale, the main mathematical object in inflationary cosmology, is just the latest example. Clearly Mark and I thought of the same thing immediately, thanks to the fact we've actually learnt something about the specifics cosmology rather than just ignored it all.

Please explain to me how you're in any position to discuss tensors, mathematical constructs, when you cannot do any of the mathematics? You have had a go at me (and others) more than once when we talk about the space-time metric, reminding us the metric isn't a real thing, it is a mathematical non-physical thing, yet here you are talking about the stress-energy tensor, a mathematical construct just as physically real (or not) as the metric, both are conceptual formalisations of physical phenomena/structures. At least in my case I understand the mathematics underlying the tensor about which I spoke. If you really understood the current state of cosmology, enough to blow holes in it etc and understood the tensor construction of the FRW metric etc then you'd have known how a(t) counters your claim. But you didn't because you don't. You never do.

Now you can (and likely will) ignore my criticisms but they are all completely valid. It isn't an ad hom to point out you don't know tensor calculus, it is a statement of fact. A fact you might not like to acknowledge but a fact nonetheless. Thus questioning how you're in a position to be throwing around such concepts as if you understand them

*is* a valid question. Likewise for how you 'know the trick' of string theory when you lack all of the necessary mathematical knowledge required to do anything but read pop science books or watch TV documentaries on it. Likewise it is a valid criticism of your actions when I point out your hypocrisy for railing against the supposed unfalsifiability of string theory when your work has

**less** falsifiable quantitative modelling connections to reality. By which I mean it has none. Is it an ad hom for me to point that out? No, since I'm criticism your work for having absolutely no structured connection to reality, rather than saying "It is wrong because

*you* wrote it". Likewise when I point out the ridiculousness of you claiming to be a world leading expert in (amongst other things) electromagnetism. Why can you not do any of the mathematical stuff then? Hard to be a world leading expert in a physics domain when you cannot model any physical system, despite accurate, well tested quantitative models existing. Is that an ad hom? No, the claim is ridiculous because it is demonstrably false, rather than because

*you* said it.

I love cosmology, I love science and I wish more people knew more of it but that is also why I see your actions as somewhat reprehensible. By misrepresenting yourself as understanding something you are demonstrably ignorant of and telling others 'how things are' without making it clear when you're injecting your own 2 cents into things then you take a proverbial **** on science. If you cared more about science and less for making a name for "John Duffield" you'd not be as you are. Ignoring these

*valid* criticisms of your behaviour and mindset is your prerogative but it's those behaviours which hold you back from do actual science, in whatever capacity, large or small, you are capable of.