I have a few problems with these theories on the universe. Why am I wrong?

Just butting in to agree with you. There are several ideas in science – Many Worlds and String Theory are two notable ones – that are not yet well-enough developed, and which do not yet make sufficiently testable (falsifiable) predictions to be called “theories.”

They’re notions. Ideas that people throw around. They might very well be true, but at this time, they lack concrete definitions and testable implications.

I’m not comfortable with people who reject them as “nonsense,” even though, in the strictly limited definition of scientific philosophy, they kind of are. I think they make just enough sense to be worth discussing, worth visualizing, worth “playing around with.” An awful lot of things we accept today got their start as raw conjectures. So, of course, did a lot of things we reject today!

No, since none of your experts claimed that Many Worlds is a “*scientific *theory”. I can concede that all those experts know far more than I do, but they never used the term “scientific theory” to refer to the Many Worlds *interpretation. *

Experts or geniuses they may be, but they still occasionally use English in a way that is sloppy. I don’t blame them a bit. I blame the sloppy writing and editing of SA.

But I see you are still falling back on the “*Well, that there “Theory of Evolution” is jest a theory, anyway” *meme. :rolleyes:

Oh yeah-- String Theory! That’s T-h-e-o-r-y THEORY, as it is universally referred to.

I mean, has any one ever heard of String “Notion” String “Idea” of String “hypothesis”?
Be honest now.

Our friend DrDeth is in love with Wikipedia? Fine, check it out:

(from link, emphasis added):

That, ladies and gentlemen, is three, count 'em three uses in the introductory paragraph
of the word “theory” for a notion or whatever for which not a scintilla of observational evidence
has been detected after nearly 50 years of um, er, ideation.

A letter of complaint is not nearly good enough. Someone start a petition to the attention
of the Wiki administration about their slovenly misuse of scientific terminology.

There’s a difference between the String Model and the Many Worlds interpretation, though. The String Model could, at least in principle, be tested. It would be insanely hard to do so, and might even require more resources than are present in the entire observable Universe, but in principle, it could be done. The Many Worlds interpretation, though, absolutely cannot be tested, not even in principle, since it makes exactly the same predictions as every other interpretation of quantum mechanics. Whoever put together that FAQ clearly doesn’t know what they’re talking about, as evidenced (for instance) by their talk about minds: Quantum mechanics cares not at all about a “mind”, whatever the heck that might be.

They don’t need to, and you don’t either since it fails as a device for keeping
that raft you are on from sinking right in the middle of shit creek.

Right. Three geniuses all screwed it up, and here is DrDeth to clean up the mess
they left behind. Thanks Doc!

Me and Wikipedia, huh? Aren’t you the one who is in charge of the petition going
around about how Wiki needs to stop misusing the word “theory”? Praised be
the Lord for people like you to guide us!

String “Model”? I think that might be considered an example a hobgoblin of consistency.
Or do people like E. Witten actually refer to the subject of their life’s work as a “model”?

The Wiki article on MW has a paragraph titled “Comparative properties and possible experimental tests”.
It ends by saying: “As of 2010, there are no feasible experiments to test the differences between MWI
and other theories,” but that is not the same as saying MW cannot in principle be tested.

And Dr. Deth is right that the colloquial use of the word is not the proper, formal, specific scientific term; it’s used this way in journalism, not in real science.

This certainly invites an intriguing philosophical discussion. Is an idea “nonsense” if it can’t be tested at our current level of technology and understanding? I would say yes… In the year 1750, the idea of determining the chemical composition of distant stars would be nonsense. When spectrography came along, the idea suddenly became wonderfully sensible.

Similarly for Bertrand Russell’s teapot: the idea that there is a teapot in orbit between earth and mars is nonsense…today. But in the future, long-distance, highly accurate radar might be invented that could, in fact, sweep the whole area and identify every piece of debris, even to the size of a teapot. As you say, the idea can, in principle, be tested; we just don’t have the radar, today, that can do the job.

I doubt the word would be bandied about as it is by the leading minds of the field if to do so was
a real affront to scientifically correct terminology.

Here is a site with links to several articles by Edward Witten, preeminent in the field of Strings:

The phrase “String Theory” is ubiquitous.

All right now, how do we deal with this?:

Three String Theory Textbooks

Textbooks, get it?

Three older textbooks are:

(from link):

And there are three newer ones, all with the words “string theory” in the title.

I really wouldn’t get hung up on the word “theory” here. String Theory is as more mathematics than it is physics, and in mathematics theory has a rather different meaning, one for which its use here is not unreasonable. The contentious question is whether all this lovely mathematical theory has any connection with our physical reality.

Ed Witten got a Fields Medal. That says a lot about where the action is in string theory. Whilst a lot of people think that the action in fundamental physics is in strings too, not everyone agrees.

Thank’ee kindly. Maybe it wasn’t the best choice in the world, but String Theory as physics is certainly very highly controversial, and has been openly called “nonsense” by at least a few reputable physicists. In any case, Dr. Deth is technically correct. In the sciences, especially, words have rigidly defined meanings. The same is true in law.

(In another thread, someone used the word “robbed” when it ought to have been “burgled.” In commonplace English, nobody really cares. But in a specific legal context, the word was wrong.)
ETA: Here is a reference to a book attacking the idea pretty violently. If the author is correct – IF! – then it would seem that the idea does not rise to the level of concrete explicitness required for it to be a formal theory. (If the author is incorrect, then never mind.)

There is infinite number of everything in all directions. Why not universes? Relax, open your mind and expand. How infinite do you think your hand is for example? It’s without end. How can it not be true? The end has not been found in either direction. Think about your mind and how it exists. Our minds are immeasurable, so to is everything else. I like to say, take everything that is good, condense to its purest, and you can find this in us all. So relax and enjoy your fortunate existence. Find peace within yourself and you will find it outside as well. It’s time to enjoy, let’s have some fun.

Not Even Wrong is a great read. My mention of “where the action is” is a direct quote from there. The context being - ask a physics PhD student why they are burning their lives away on string theory, and the answer is “it is where the action is”. This isn’t a good reason. (There is probably a geeky pun on “action” here, but I’ll ignore it.)

Because there isn’t any evidence for them… There is at least a little evidence for an “open universe,” where you could go “that way” forever and neither reach the end nor return to where you started. But there is no evidence whatever for either of the four most useful kinds of “other universes.”

(One being quantum mechanics “many worlds” interpretation, where the Uranium atom decayed here, but did not decay over there. The second being the higher dimensions involved in String Theory, where there are additional dimensions, simply “rolled up.” The third is the “other regions of space” idea, where there may be huge vast tracts of land…space, that is…which were built up in the “Expansionary Phase” of the Big Bang. And the fourth is that our entire cosmos, from the Big Bang up, is just one small bubble in a vaster foam of bubbles, each one having its own Bang. A gigantic glass of champagne!)

I hit on it mostly by chance, having Googled “String Theory Nonsense.” (As you might imagine, I got a LOT of hits!)

And, of course, there’s nothing wrong with following the action in science. It might be Einsteinian space/time. Or, alas, it might be Cold Fusion. But no one can tell, in advance, what will be a hit, and what will be a bust. In science, it is almost as much a triumph to discredit a bad idea as it is to confirm a good one.

There is some sort of semantic confusion around the word “dimension”. Mathematically, a dimension is merely some aspect that can be measured on a linear scale. The fact that we can set up three axes and measure linear distance along them does not specifically exclude the possibility of other linear universal aspects (in addition to time) that could qualify as dimensions. All they have to be to be dimensions is to be universal, linear and measurable in some way. “Rolled up” is just short-hand for “not readily observable with the tools we have at hand”.

Is snot not full of bubbles?

Let’s not bother with semantic quibbles. I think we all agree on what MW is, we’re just disagreeing on what we call it. That’s semantics.

Yeah, I read that. I still don’t see why human-level intelligence is required. (Nor do I put much faith in their estimate of how many bits are required in a digital computer to emulate human intelligence.) One interpretation is that we need an “observer”. Would a universe with only insects in it to observe, not exists, due to there being no observers? In any case, the requirement for AI is stated, not explained. The tests posited can be done without human intelligence.

Right, that’s just what distinguishes a “historical science” from others, and it does make things more difficult. However, predictions can still be made and tested. Often the tests are positive-only (meaning, if we find X it corroborates the theory, but not finding X isn’t conclusive). It’s still a science, even by Carl Popper’s limited (and largely outmoded) definition. Popper was nearly correct, for his time, but science has moved on to fields where his definition doesn’t apply. Most philosophers seem to think that this doesn’t mean it’s not science, but that Popper just didn’t cover everything.

'Snot true.

Here’s the thing. Dudes get hung up on “whenever I make a decision, another universe splits off”. But that’s not it- it whenever anything happens that has different ways of happening a universe splits off.

Taken to an extreme, we’ll take molecular motion. Molecules move erratically (Brownian motion). So, every millisecond, every human generates about 60 trillion universes. Well, somewhat less as not all of a yuma is liquid. But still.

The Universe has like 10 to the 80th power atoms, which if they are all moving erratically, that many universes are generated every fraction of a second.

It’s just infinity upon infinity.

That doesn’t make the interpretation wrong mind you. It’s just that no-one can really comprehend it. Feyman even said that no one can (truly) understand quantum physics.

People have told me that some of these alternate universes merge again – but this always struck me as uncomfortably close to a denial of causality. There is more than one “past” that can lead to the present? One donkey, two tails? (Miles Prower notwithstanding.)

I would have thought that, once split, the universes could never be in contact again. Otherwise, couldn’t signals be sent between them, giving away forbidden quantum information? (“Psst, hey, Joe, that electron, the one entangled with the other electron? In my universe, its spin is ‘up.’ Thought you’d like to know.”)