To my greatly over-whelmed mind, this makes more sense to me than the idea of infinite repetition. Of course, an infinite number of me disagree.

The argument is somewhat misplaced, "infinite" does not imply all possible universes exist, like a copy of this one except my hair is red.

Example, pi is an irrational number, and the computation of that number carries out infinite places, it never ends. Even so, no matter how far you looked, you would never find the numeral 1 repeated a trillion times, never.

Perhaps there are endless numbers of universes, and some might have similar physical laws. But never would you find the mega godzillion particles assuming the exact same configuration some billions of years after the universe began expanding. Can't happen.

Isn't more like on some underlying quantum level, an infinite number of probabilities is possible for any given "now moment" configuration, and only the "now" before your eyes "collapses" into apparent reality?

I'm pretty sure thinking of time and reality as a forward "flow", with alternative paralleled universe "flows", is the old paradigm, and new sciences show that what appears to be reality is not really reality as we intuitively seem to grasp it eh

These authors obviously haven't read David Deutsch's "Fabric of Reality."

its probability would be 1 divided by infinity, which is zero


I'm not sure this can be applied to the case.

The mathematical reasoning is that between every real number there must be an infinite amount of numbers, and since between 1/inf and 0 there is no other number, then both must be the same number.

But when applied to real things that come in integer amounts, that's like saying that since there isn't a house between my house and my neighbor's house, then our houses must be one and the same.

The mathematical axiom that leads to this conclusion causes obvious paradoxes when you apply it to things like the probability of life, because if you claim that the probability of something happening, even in infinity, is zero, then there must be no cases of that.

Perhaps this is what they mean by being constrained by classical thinking. Maybe there is a house between my house and my neighbor's - in some weird quantum sense - that must be there for both to exist apart.

I haven't read the paper, so don't know how the author's carve up the different ideas of the Everett interpretation and an infinite classical universe. For sake of brevity I shall only comment on the latter.

An open question in (e.g. quasiclassical) cosmology is as to whether the universe is infinite or finite. As the author's acknowledge, this problem is currently unsolved. So everyone, both critics and supporters of the infinite classical spacetime hypothesis, is in the same boat: we don't know. It seems strange, therefore to pitch a critique at the level of this uncertainty. Since the argument for the infinite 'repetition' of finite physical systems throughout putatively infinite classical spacetime is essentially an IF-THEN conditional, an appropriate critique must also adopt this format. I.e., the critique must take the form of IF infinite classical spacetime, THEN 'infinite repetition of finite physical system's' doesn't occur, for some reason.

After scanning the paper, I cannot see where the author's really offer a conditional argument of this form. Introducing probability into the account is very difficult, since all outcomes occur in an infinite classical universe, every frequency-interpretation of what those numbers we call probabilities are sum to unity. Thus we don't know if the frequencies are probabilities, just that as the trials tend to infinity it becomes more probable that they are. But who's to say we don't live in a giant dutch book with regards to cosmological hypotheses?

PS don't see what's so ironic about any of this!

EDIT: Above I refer to infinite spacetime, when I should write either 'infinite space' or 'infinite space(time)'.

Some variation (existence) still has to be infinite, because it is not possible to have something from nothing (no bits of informations, no two distinguishable entities of any kind). The nothingness would be equal to sameness in this sense (even in a topological sense), and therefore unable to give rise to any change. And there's plenty evidence for existence (change). And if it is infinite, and has occurred once, it can occur again, at least in the present state. Of course, all the combinations are not implied by this. But infinite us are, even though not at the same space-time (in a sense of being able to interact with one another) necessary.

Of course the argument of 1/inf = 0 depends on if you consider infinity to be a number in the first place.

Because either one has to give: either you stop requiring that real numbers have other real numbers in between them, which would mean that there's a finite number of fractions between 1 and 0, or you admit that 1/inf is not a number and therefore the argument they propose is flawed.

But this dichotomy depends on the definition of a number. Since the occurence of life comes in integer amounts - it either occurs or it doesn't - the same concept of a number doesn't apply and the same concept of infinity doesn't apply, and therefore it is not given that 1/inf = 0 even if we consider inf to be a number.

This comment has been removed by a moderator.

Continuing on the idea:

Since life either occurs, or doesn't occur, it doesn't come in half measures. We're dealing in positive whole numbers, where the rule of every number having other numbers in between them does not apply. Otherwise we would have to conclude that 1=0 since there isn't a positive whole number in between them.

Therefore we must conclude that in this case 1/inf is either not a number, or it is not zero.

If it is not zero, then it must be one since the occurence of life does not come in half measures. In other words, if life occurs in one permutation of history, it must occur in all of them, and if there are infinite permutations of history then there is infinite permutations of life.

If 1/inf is not a number, then we are none the wiser about the probability of life in each permutation of history.

@Eikka - If 1/inf isn't a number, what the hell is it??

Assuming it is a number for the time being, what is the justification for considering this number a probability?

Ahh Infiniti. I postulate that in an infinite univers, there must be a planet made entirely out of McDonald's McRib sandwiches. Each of them exactly alike.. and another planet almost exactly the same, except one of them has a curl to the slice of onion making it slightly askew... and a third with an exact copy of me on it, except that he speaks with a British accent and doesn't eat pork.

Oh, the irony.

Theoretical cosmology "highly speculative"? Gee, really?

It's evidence of creation, albeit indirect one: only God doesn't repeat the same mistake again... If the Universe would be a simulation running at Windows, we would be rebooted many times already...

BTW Is the idea "we exist in an infinite number of places" equivalent the concept of "infinite repetition, the idea that planets and living beings must be repeated an infinite number of times"? I'm missing the logics even in the article title.

The idea that 1/inf = 0 is stupid. If it is zero, than infiniti is zero. Meaning that if you had 1 unit of infinifi, and it has a 0 value, then all the units of infiniti also equal zero and infiniti itself equals zero. And if you divide 1 and infinite number of times, it could never be zero, unless the value of 1 is in fact zero.

Theoretical Cosmology needs to start thinking WAY outside the box, and try to find patterns in the micro and the macro. Just as the branches of a tree look like a tree, so do atoms look like solar systems. The answer is in the patterns....

What is this silly concept that the Universe is not a "perpetual motion machine"? That they do not believe in a "flat infinite universe" is such blatant mis-education that you might almost think these guys believe what Einstein stated in Section 30-Part 3 of his thesis on General Relativity that the Universe is a finitely spherical domain.

I think these are two guys imagining themselves to be as intelligent as Einstein, you know, newcomer wannabees who have finally figured out "entropy" cannot occur in an infinite Universe. Maybe I should have them send me their resumes, we're always looking for good people who innately understand Conservation of Energy principles cannot function in an infinite unbounded Universe.

These guys seem to be missing the point, for any given volume of space time there is a finite number of possible combinations and interactions which can unfold before the pattern must repeat! just as there are only so many possible moves and positions on a chessboard.

to be removed please

Entropy is required to balance equation

Paul Dirac once stated that the most important challenge in physics was "to get rid of infinity."

Because infinity in a physical theory means "you need to work on this part."

Of course the argument of 1/inf = 0 depends on if you consider infinity to be a number in the first place.

Because either one has to give: either you stop requiring that real numbers have other real numbers in between them, which would mean that there's a finite number of fractions between 1 and 0, or you admit that 1/inf is not a number and therefore the argument they propose is flawed.

But this dichotomy depends on the definition of a number. Since the occurrence of life comes in integer amounts - it either occurs or it doesn't - the same concept of a number doesn't apply and the same concept of infinity doesn't apply, and therefore it is not given that 1/inf = 0 even if we consider inf to be a number.


If Space and time are quantized in some fashion then the concept of the very small becomes just a mathematical quirk with no basis in reality.

I seem to think that infinities have no place in the universe, how one proves it is another matter.

The problem with this theory is that there must be an infinite number of Milky Way galaxies and even extending our scope into the earliest time of Creation we only know of this one. In agreement with the theory, however, is the idea that there are an infinite number of unique and original entities.

1 divided by infinity is in fact zero. That isn't really hard math.

The McDonalds McRib thing is funny but not valid because only finitely possible things will happen an infinite number of times. And a planet mass of McRib sandwiches, configured into a planet formation, will compress into... a planet. Potentially a very nice smelling planet with weird BBQ slicks on it's surface. But not a ball of McRibs going all the way down. :)

Le's not forget the bun, coke and fries....

I seem to think that infinities have no place in the universe, how one proves it is another matter.


How you prove it is by studying "ENTROPY". Then you will discover that if the Universe really were "infinite", the amount of usable energy available for "work" would have been exhausted within a few centuries after the occurance of the Big Bang.

These guys are unwittingly giving Einstein credibility in Sect 30-Part 3: "Considerations on the Universe as a Whole", "The Structure of Space According to the General Theory of Relativity". This is interesting reading if you've never done it.

If Space and time are quantized in some fashion then the concept of the very small becomes just a mathematical quirk with no basis in reality.


The point here is that the existence of life in the infinite universe IS quantized. It either exists or it doesn't exist. There's no in-between states.

Which means that fractional probabilities of life are non-sensical regardless of the size of the universe. If there's two separate cases of life, then the probability is 2, and so on.

The probability of life in the universe is always a positive integer, and with positive integers there is no 1/x because there are no fractions smaller than one. That's why there exists no 1/inf either. The only case when it is defined is when x=1.

And 1/0 is not defined because the limit is different when you approach it from different directions. It doesn't converge to any number.

That's why it's not technically infinite either, since approaching zero from the positive or negative side gives you two different infinities, positive and negative respectively. The same number would be two completely opposite numbers, which makes no sense.

Only |1/x| is infinite when x=0

The idea that 1/inf = 0 is stupid. If it is zero, than infiniti is zero. Meaning that if you had 1 unit of infinifi, and it has a 0 value, then all the units of infiniti also equal zero and infiniti itself equals zero. And if you divide 1 and infinite number of times, it could never be zero, unless the value of 1 is in fact zero.

@krundloss
To be technical, 1/inf = 0 is really a shorthand notation for the following:

Lim 1/x = 0
x->inf

This is the concept of a limiting value. The statement says that the quantity 1/x approaches 0 as x approaches infinity. While 1/x cannot ever be exactly 0, given any value you choose arbitrarily close to 0, I can choose a value for x in which 1/x is closer to 0 than your value. Thus, 0 is the limiting value of 1/x. Limits are the central concept in calculus and it is shorter to state 1/inf = 0 than it is to go through the verbose statement of the problem in terms of limits.

The point here is that the existence of life in the infinite universe IS quantized.


Why ponder the "infinite universe" when we can reduce our pondering to something more manageable,,,, planet Earth.

Which means that fractional probabilities of life are non-sensical regardless of the size of the universe. If there's two separate cases of life, then the probability is 2, and so on.

[qThe probability of life in the universe is always a positive integer,


The probability of life in the universe is unity,,, ONE. Assuming that I (a real living organism) am responding to you.

The reason 0 is undefined, is because any fractional part of something must be, by definition, more than zero. You can not divide something into 0 parts, it can be the whole or some part of the whole. Dividing by 0 the same as dividing infinity by infinity. It's why we do everything we can to eliminate infinity from practical science. It is in the realm of philosophy not science.

Next they'll deny that the Inquisition ever happened.

It all depends on your concepts and definitions.

If we live in a multiverse of infinite universes then YES you EXACTLY as you are now exist in infinitude. This is the definition of infinity, it's endless. This is a philosophical construct, not a mathematical one.

If you're asking if you can win the lottery by going back in time with the numbers then yes you can...it's just going to take you a loooooooooooong time and a LOT of iterations :)

It all depends on how you parse the situation.

If there's two separate cases of life, then the probability is 2, and so on.


Probabilities are never greater than 1 (ONE), they can infinitesimally small, but never greater than 1 (ONE).

Next they'll deny that the Inquisition ever happened.


Wait a minute here!!! Do you mean to tell me that the Inquisition did in fact happen? Are you sure? Who would have thunk it was a real thing?

Example, pi is an irrational number, and the computation of that number carries out infinite places, it never ends. Even so, no matter how far you looked, you would never find the numeral 1 repeated a trillion times, never.


Why not? On the averages each trillion-digit sequence happening once in each 10-to-the-trillion digits. 63.4% of all possible trillion-digit sequences will occur at least once in the FIRST 10-to-the-trillion digits.
There is a 69.4 (1 - 1/e = 0.694) percent chance that a trillion ones in a row occurs in ANY 10-to-the-trillion digits of ANY irrational number.
The odds are only ~ 1 in ten trillion of a trillion ones in a row NOT happening in the first ten-to-the-(one trillion + 30) digits.

Enough work to deal with one universe. Why must they always complicate things by suggesting an infinite array of universes?
For all their attempts to find a 'unified' theory of everything; they still insist on using Occam's Razor to continually divide it into finer and finer portions...

The reason 0 is undefined, is because any fractional part of something must be, by definition, more than zero. You can not divide something into 0 parts, it can be the whole or some part of the whole. Dividing by 0 the same as dividing infinity by infinity. It's why we do everything we can to eliminate infinity from practical science. It is in the realm of philosophy not science.


It's also the same as multiplying Zero by Infinity.
But, if you ascribe to the Big Bang theory; then you believe in the something from nothing concept. Before the Big Bang, they would have us believe there was nothing; then after, everything. From Zero to Infinity in one absurd theory.

This all a conspiracy by the (insert conspirator here) to starve humanity and take over the world.
If it is not happening in this reality, it must be happening in another.
We were right all along.

But, if you ascribe to the Big Bang theory; then you believe in the something from nothing concept. Before the Big Bang, they would have us believe there was nothing; then after, everything.


I do in fact ascribe to the so-called "Big Bang theory". Though I think the term "Big Bang" is unfortunate. I would call it the "Standard model with cold inflation", but they didn't ask me, so the name is what it is.....

But this model by what ever name, doesn't assume a priori that everything came from nothing,,,, quite the contrary,,, the theory stops at the so-called "Planck-time", when everything that is here was already there, before that it makes no predictions.

Many people speculate on what existed, or if anything existed before the Planck-Time, but those speculations are not part of the standard "Big Bang w/inflation" model. The only ones who claim it is are the detractors of the "Big Bang" model.

Currently the two basic theories in physics, general relativity and quantum theory, both predict infinities. In relativity, it's gravity singularities in black holes and the big bang. In quantum theory, it's vacuum energy and certain parts of quantum field theory. Perhaps both theories are simple approximations of a third more general theory without infinities. ….

Or in one sense, the 'infinity' problem arisen because both the theories' main theme is mathematic –not physics! They are no philosophy background which explain what mechanism hidden behind and how it works. Maybe this physics oriented theory could solve the problem.
http://www.vacuum...=9〈=en

No one can conceive what the nature of infinity really is, except what you can see through mathematics. Some human theorists seem stuck in a mental Möbius loop concerning reality and possible infinite variations thereof. Personally I'm a big fan of Occam's razor and I can't believe that the universe - quantum reality and all - would go to all the "trouble" to work with any sort of infinite framework. It seems like an awful waste of energy, something that goes against nature. Just a layman's 2 cents.

In an infinite universe a particle can move through space in some arbitrary direction and continue to move in that direction for an infinite amount of time. This event can not then, by definition, be repeated.

Therefore the statement "In an infinite universe, every possible event does happen. Not just that: it happens an infinite number of times." is false. The universe would have to have a finite spatial extension and infinite temporal extension for all event to be repeated.

The interesting aspect of this is that in some parallel universe the same scientists have come to the exact opposite conclusion.

And they are made from Candyfloss.

The hall of mirrors model of Universe considers quite seriously, we could observe some portions of our Universe at the multiple places. This theory is a subject of experimental verification by now - so we could save money for something more useful.

What the dense aether model says about it? The Universe is filled with foamy density fluctuations (dark matter streaks) which may act like reflecting barriers for low-energy light (the interior of black holes is behaving like mirror in AWT). Which means, that some CMBR structures may be really reflected in the infrared light from the inner cells of our portion of Universe. Therefore some very subtle structures may exist at the multiple places of Universe or at least being observable so. The more dense structures are indeed quite random and as such unrepeatable. This may serve as an example of proverbs "There's a bit of truth in every gossip. There's no smoke without fire".

The interesting aspect of this is that in some parallel universe the same scientists have come to the exact opposite conclusion.

And they are made from Candyfloss.

Dang... VD strikes gold again...
The white rabbit must die...

Dang... VD strikes gold again...The white rabbit must die.
VD is trying to do the fun at any price. This is just a semantic twaddling, which cannot be opposed and falsified - so it has no place in discussion bellow scientific article. We have number of Internet discussions full of bored twaddlers already - why to expand it here?

Dang... VD strikes gold again...The white rabbit must die.
VD is trying to do the fun at any price. This is just a semantic twaddling, which cannot be opposed and falsified - so it has no place in discussion bellow scientific article. We have number of Internet discussions full of bored twaddlers already - why to expand it here?

My only answer is - without a little humour and the subsequent appreciation of it - we might as well just end it all.
It's Friday... relax and have a little fun...:-)

Hear, Hear, Whydening Gyre. As for the concept of multiple dimensions- there IS proof of it. In the mid-1800's there was a spirit medium named Daniel Dunglas Home, one of the most documented of that era. He was vetted by none other than William Crookes, a highly esteemed scientist whose own work is still referenced, and was also the inventor of the radiometer. Crookes witnessed, along with others, Home's levitations and spirit manifestations in daylight, professing afterward that Home was legitimate. While many scoff at the "very idea" of another dimension of existence, it nonetheless is true. An infinite number of dimensions cannot be ruled out if there already exists more than one.

Another stupid comment. I won't read it. I did, fuck! Another me
Another stupid comment. I won't read it. I did, fuck! Another me
Another stupid comment. I won't read it. I did, fuck! Another me
Another stupid comment. I won't read it. I did, fuck! Another me
Another stupid comment. I won't read it. I did, fuck! Another me...

You, Anda, have diarrhea of the keyboard. All that verbiage for a joke that falls flat. Now go hose yourself off.

I think they are mixing up two ideas here. the first one being infinite universe, the second is infinite multiverse. The universe we live in is finite. I am not a scientist, but i am pretty sure that the position of science is that the universe is finite. The infinite multiverse is another issue. It seems this separation is blurred here. that makes a world of a difference.

Well, this totally explains why potential boyfriends act as though I'm invisible.

Unfortunately, it is also possible that we live in a universe in which only one intelligent lifeform exists at a time in any place in all of the possible universes. And the next possible intelligent lifeform doesn't exist until after the first one and possibly its entire existance and anything that it influenced goes extinct (or something else causes it to stop existing). So lonely...

... pi is an irrational number, and the computation of that number carries out infinite places, it never ends. Even so, no matter how far you looked, you would never find the numeral 1 repeated a trillion times, never.


If PI is a uniformly distributed random number (and although it hasn't been formally proven, it's generally considered a 'normal' number, with digits uniformly distributed in every base), then it must contain any finite sequence of digits -- including '1' a trillion times. Infinity is difficult to conceptualize, hence the endless back-and-forth about its precise ontological status. But it is clear from the definitions of uniform randomicity and inifinity as 'that which is as large as you want it to be' that every finite sequence must occur within an infinite string.

universe has infinite time ,there's no crisp "yes" or "no" answers ..it's just probabilities

without a little humour and the subsequent appreciation of it
The things will get wrong, if the attempts for humor become dominant. The approach of twaddlers here is equivalent to the approach of contemporary scientists. They don't want to solve and answer the problems at the first line - they just want to keep their fun, as Robert Wilson already recognized and named before years. Not surprisingly, most of them refuses the cold fusion from the same reason.


Construct your infinite models. Your time is limited.

This is about as close to the truth as we can possibly get.
We can make the provable observation that Time is the ONE thing that everything else is related to on one level or another. Yet - somehow - that fact gets obfuscated by the rush of all the other stuff we're observing...
Dang... Why can't I get this damn white rabbit out of my head?

Oh, Lisa Zyga, here you go again...I hope you get paid well for all these pranks.

Another atrocious Phys.org article, well paid prank or not. These authors are philosophers, not "scientists", not even publishing in philosophy proper but in a history of philosophy series. It positively screams "foul", and indeed there is no scientific criticism of Garriga and Vilenkin for example.

Another problem is their lack of understanding of physics. For example, it is an open question if the initial inflation in standard cosmology runs into singularities if you go backward in time. Planck scale potentially, but we know from cosmological supernova photons that physics happens on a smooth manifold even below that scale.

Mostly, the generic argument for repeats, not of history necessarily but of the exact same events, is that the observable universes is finite and have a finite number of particles. So you have to happen on the same configurations elsewhere. (Cf Tegmark's multiverse.) And the simplest standard cosmological universe is infinite.

Paul Dirac once stated that the most important challenge in physics was "to get rid of infinity."

Because infinity in a physical theory means "you need to work on this part."

Infinity, no matter how much we are seduced into thinking we can grasp it, always remains an "I don't know what." Infinity is always an undefined. When infinity shows up as the result either in mathematics or in physical theory it points to a something that lies outside the calculational or descriptive power of whatever mathematical or physics model one is using.

Note that in holographic model you're actually existing somewhere else already: you're projected from surface of black hole at which you're living it. So you can be projected into many different places at the same moment. As a proponent of dense aether model I don't believe in holographic model - I'm just pointing to the fact, that the multiple existence concept has already a certain roots in contemporary physics.

I think they are mixing up two ideas here. the first one being infinite universe, the second is infinite multiverse. The universe we live in is finite. I am not a scientist, but i am pretty sure that the position of science is that the universe is finite.


IF you watch the Universe series on History & Science channels, nearly all the Asro-Physicists & Astronomers conclude with you that the Universe is finite. These are people who fully understand the greatest & most far reaching concepts of Conservation of Energy & Einstein's Theory of General Relativity which does not allow for "infinity".

The infinite multiverse is another issue. It seems this separation is blurred here.


It may very well be that the Universe we live in may be a "stellar island", & beyond the domains of this stellar island may very well be other stellar islands, but a Conservation of Energy principle we call "entropy" will prevent us from ever viewing through or crossing that barrier.

It has never been very clear to me why the concept of a singular origin of the universe is maintained if the existing laws of physics must immediately be violated to expand that singularity to some finite size.

"For example, it is an open question if the initial inflation in standard cosmology runs into singularities if you go backward in time." - Torbjorn

It makes much more sense to me to simply have matter manifest itself from nothing through the entire volume of the space/time manifold.

but a Conservation of Energy principle we call "entropy" will prevent us from ever viewing through or crossing that barrier.


Whose we are you calling yourself? I ask because WE call "conservation of energy" the 1st Law of Thermodynamics. And WE associate "entropy" with the 2nd Law of Thermodynamics.....

Oh yeah,,,, yes I took several course devoted to thermodynamics. And made very good grades in them.

It has never been very clear to me why the concept of a singular origin of the universe is maintained if the existing laws of physics must immediately be violated to expand that singularity to some finite size.
Because the general relativity points to the expansion of Universe and this expansion may run from very small object only. Lamaitre called it "primeval atom" and it's of ideological, not physical origin. Whole the expansion stuff is therefore a fringe science, not just Big Bang event.

The red shift is observable at the water surface due the scattering of light waves. At the end all waves are scattered into Brownian noise, so all larger objects would appear shrunken into the very same size (~ 1,7 cm), when being observed at the water surface with surface ripples from distance. But it's the wavelength if light waves only, not the space-time, which is collapsed there.

In L-CDM theory the geometry of Universe is described with FRLW metric, which is essentially the black hole geometry inverted. But we aren't traveling against time, when we are falling into black hole, so I don't understand, why the traveling into distance within cosmic space isn't interpreted in the same way. For me the whole the idea of space-time expansion has absolutely no sense. The Universe beginning just brings another questions, so it doesn't solve anything anyway-it's causally redundant hypothesis.

@zorro6204 - it has nothing to do with this article, but kids in school (around 5 or 6 grades) already know that pi has any combinations of numbers - even gazillion ones following each other. And it can be proved very simply.

Dang... VD strikes gold again...The white rabbit must die.
VD is trying to do the fun at any price. This is just a semantic twaddling, which cannot be opposed and falsified - so it has no place in discussion bellow scientific article. We have number of Internet discussions full of bored twaddlers already - why to expand it here?

Entertainment - which is why we all are here in the first place...

In-adequacy of the present state -is very clear.
Perceptions need to cross-over to Cosmic Vision development.
ignore the origins-you will end up no-where
Does it boil down to psychology of Human perception ?

Oh look, a fairy-tale promoted by a physics publication! Totally novel, given it is totally opposite from the daydreaming doctrine that was official until this morning. Ask Sean Carroll.
beep-beep Earth calling: "How Wineland & Haroche Stole My Discovery (and got 2012 PHYSICS NOBEL PRIZE for it...)" http://sites.goog...ci#Nobel

Apparently there's been some inbreeding in the royal family of Bosnia.

... hey guys, while you're at it could you have a go at the "Infinite monkey theorem" as well ...

``Perhaps this is what they mean by being constrained by classical thinking. Maybe there is a house between my house and my neighbor's - in some weird quantum sense - that must be there for both to exist apart.''

---------

With the possibility of infinite arrangements, just slightly out-of-phase and thus shifted so that from the view of seeing all potential shifts there are an infinite number of houses between both homes in your singular view.

While Soler Gil and Alfonseca can't disprove the proposals of infinite repetition, they emphasize that the point of their critique is to show that the idea remains in the realm of philosophy, mythology, and sci-fi tales, not modern cosmology.
I think this sentence was the most important one in this PhysOrg article. Since so much in quantum mechanics requires you to leave your common-sense brain at home, it inevitably follows that many proposals get carried away. Unfortunately.
They call the speculation "ironic science," a term used by science journalist John Horgan to describe options that do not converge on truth but are at best "interesting."
The sheer number of the competing theories on quantum mechanics and cosmology shows this.

I wish more time would be used to finding unrepairable holes in existing theories, instead of everybody building their own.


I wish more time would be used to finding unrepairable holes in existing theories, instead of everybody building their own.

Unfortunately - we can't. Not the way our (quantum) brains work...

Let's talk about the McRib planet again. It intrigues me. Does it include a vanilla milkshake moon?

It has never been very clear to me why the concept of a singular origin of the universe is maintained ...


It is just a pop-science thing. The FLRW metric is based on GR which is classical so if you extrapolate to t=0, you get a scale factor a(t) which is also zero, and many parameters such as energy density become a division by zero, a singularity in the maths.

If you take a cosmology course, the real science stops at a time expected to be of the order of the Planck Time. To project before that we need a quantum theory of gravity which as yet doesn't exist.

Infinity does not imply infinite variety. Infinite homogeneity is logically consistent.

we need a quantum theory of gravity which as yet doesn't exist
This is just a parotting of common employment scheme of mainstream physicists - but what the quantum gravity theory is supposed to describe actually? It must describe just the observable reality BETWEEN quantum mechanics and general relativity scales, i.e. the scale of human observer with trees, rivers and ducks on it. There are no trees, ducks and rivers at the most distant/oldest areas of Universe and such a theory would be useless there.

Why do you think 1/inf = 0 is stupid? Consider 1/x. It's clear that as x approaches infinity then 1/x -> 0. If you define 1/inf = lim x-> infinity of 1/x then that limit is 0. Similary you could also define 1/0 as lim x->0 of 1/x in which case it grows unbounded and so you could make an argument that 1/0 = inf or in fact z/0 = inf for any z.


Only approaching from the right. If you approach from the left, the limit approaches -inf. That is why 1/0 is undefined.

Only approaching from the right. If you approach from the left, the limit approaches -inf. That is why 1/0 is undefined.


The limit is the same regardless of which side you approach it from. The limit is 0. The 1/X is what is approaching 0. NOT the denominator,,,,, that is going farther and farther AWAY from 0.

Dividing 1 by infinity or negative infinity is completely equal, they approach each other to the point where they are the same point,, They converge at 0

f(1/infinity) or f(1/neg infinity) both have ZERO as a limit.

There is no 0 in the denominator, the denominator is increasing without out limit yielding a function whose limit is zero.

You guys are mixing up the concept of dividing by zero, and dividing by infinity. Dividing by zero is undefined. Dividing by infinity is NOT undefined.

But then we have this:

"Survey shows physicists can't agree on fundamental questions about quantum mechanics"
http://phys.org/n...firstCmt

IF the probability of life is zero then this whole discussion is academic because we aren't really here.

I'm pretty convinced infinities don't exist outside the ivory towers of philosophical debate. I think they are an artifact of human conceptualization.

Then again Einstein thought nature would "protect" us from singularities, even though he agreed with Schwarzschild's math...

Fundamentally, there is only ONE universe, but there are multiple "paths" thru' it. We call our "path" TIME, and it is dictated by the "laws" of physics which guide our movement from one state of the universe to another for each quantum of TIME. See "The Situation of Gravity" for the argument.

we need a quantum theory of gravity which as yet doesn't exist
This is just a parotting of common employment scheme of mainstream physicists - but what the quantum gravity theory is supposed to describe actually? It must describe just the observable reality BETWEEN quantum mechanics and general relativity scales, i.e. the scale of human observer with trees, rivers and ducks on it. There are no trees, ducks and rivers at the most distant/oldest areas of Universe and such a theory would be useless there.


You shouldn't try to comment on things you don't understand. GR describes the gravity that holds you onto the Earth, not just cosmology while QED describes the interactions that hold the atoms of your body together. Normally we can use then separately by treating one or the other as negligible, a merged theory would provide a tool to analyse situations where neither can be ignored.

Fundamentally, there is only ONE universe, but there are multiple "paths" thru' it. We call our "path" TIME, and it is dictated by the "laws" of physics which guide our movement from one state of the universe to another for each quantum of TIME. See "The Situation of Gravity" for the argument.

Why do we need "gravity" at all, it was just "invented" to explain observed phenomena? There is no actual evidence for multiple universes either, so why "invent" them? I would dearly like to see a logical refutation of Reg Mundy's "simple" theory of how the universe works.

Why do we need "gravity" at all, it was just "invented" to explain observed phenomena?


The whole of science exists to provide mathematical tools by which we can model observed behaviour. Those are the tools that allow us to engineer solutions to real-world problems. Modeling gravity in particular has allowed us to send craft to other planets, put GPS satellites into accurately known orbits and correct for the relativistic effects that affect the signals from those satellites and their on-board clocks. Next time you use a satnav, realise it wouldn't work without Einstein's understanding of gravity.

Why do we need "gravity" at all, it was just "invented" to explain observed phenomena?


The whole of science exists to provide mathematical tools by which we can model observed behaviour.

I think you have made my point beautifully, gravity is just a "mathematical tool" invented to explain reality - but it doesn't, it stops working in extreme situations. I know of no proof of its existence, do you? Someone once said "The objective of science is to remove infinity from all equations/theories". Gravity should be removed as well.

Why do we need "gravity" at all, it was just "invented" to explain observed phenomena?


The whole of science exists to provide mathematical tools by which we can model observed behaviour.

I think you have made my point beautifully, gravity is just a "mathematical tool" invented to explain reality - but it doesn't, it stops working in extreme situations.


General Relativity is the tool we invented to model "gravity" which is an effect in the real world. Gravity doesn't stop working, only GR is limited.

I know of no proof of its existence, do you?


The proof of the existence of GR is that you can find it in many textbooks.

The proof of the existence of gravity is that you don't hurtle off into space even though our planet is rotating.

Someone once said "The objective of science is to remove infinity from all equations/theories". Gravity should be removed as well.


If you find a way to cancel gravity, good luck surviving in deep space.

Why do we need "gravity" at all, it was just "invented" to explain observed phenomena?


The whole of science exists to provide mathematical tools by which we can model observed behaviour.

I think you have made my point beautifully, gravity is just a "mathematical tool" invented to explain reality - but it doesn't, it stops working in extreme situations.


I know of no proof of its existence, do you?


The proof of the existence of GR is that you can find it in many textbooks.

The proof of the existence of gravity is that you don't hurtle off into space even though our planet is rotating.

Your "proof" of gravity seems to be that "you can find it in many textbooks"! I expect that a few centuries ago you could find that the Earth was flat "in many text books", and that the atom was indivisible. And there are several explanations as to why we don't "hurtle off into space", try reading "The Situation of Gravity" for one.

I expect that a few centuries ago you could find that the Earth was flat "in many text books", ..


Nope: http://en.wikiped...at_Earth

and that the atom was indivisible.


Perhaps, scientifically it was and still is the smallest division of matter that retains the behaviour of the bulk element.

there are several explanations as to why we don't "hurtle off into space",


Alternative explanations aren't the same as gravity not existing thus needing no explanation.

try reading "The Situation of Gravity" for one.


ROFL, no thanks, plugging your book under a sock puppet account won't increase your sales. If you want me to comment on the idea, summarise it here. If it is new and credible, that will get you your sales ;-)

I didn't say you could find "the earth was flat" in ALL text books, just in MANY text books, just like "gravity" is not in ALL text books. YOU advanced the presence of gravity in text books as a "proof" that gravity exists - sloppy logic, fleetfoot.
And of course the atom is divisible, whether you like it or not, no matter how you play with semantics, and that was stated "in many textbooks".
Finally, although it is not my book, I wouldn't ask you to comment on it as you seem to have a closed mind on the subject and have failed to justify your viewpoint with a single logical argument. If you know of one proof of the existence of gravity, kindly tell me about it.

I didn't say you could find "the earth was flat" in ALL text books, just in MANY text books, ..


And my point is that you CANNOT find it in ANY text books, it was a myth created long after the time when people were supposed to have believed it.

just like "gravity" is not in ALL text books. YOU advanced the presence of gravity in text books as a "proof" that gravity exists - sloppy logic, fleetfoot.


No I didn't, sloppy reading Jack. If you look at my post, I said that its presence in textbooks showed that the equations know as General Relativity exists, not gravity. You seem to be incapable of telling the difference.

If you know of one proof of the existence of gravity, kindly tell me about it.


I already have, unless you are now flying away from the Earth at approx 1000mph. Explain it any way you like and model it with any maths you like to whatever accuracy you want, the effect certainly exists or you wouldn't be on the planet.

You cannot find it in ANY textbooks? As you are so fond of quoting WIKI, here's a WIKI quote:- "Like the Midrash and the Talmud, the Targum does not think of a globe of the spherical earth, around which the sun revolves in 24 hours, but of a flat disk of the earth, above which the sun completes its semicircle in an average of 12 hours. (The Distribution of Land and Sea on the Earth's Surface According to Hebrew Sources, Solomon Gandz, Proceedings of the American Academy for Jewish Research, Vol. 22 (1953), pp. 23-53, published by American Academy for Jewish Research."
And as for flying off the planet, you are once again quoting an "effect" not a proof, which can be explained in several ways without inventing "Gravity".
Finally, while I must say I have enjoyed our little "tete a tete", we must call it a day before we bore the rest of the phys.org readers to death. Please, have a final rant if you must, but I'm finished - you can pretend I've been hurtled off into space if you like....

You cannot find it in ANY textbooks? As you are so fond of quoting WIKI, here's a WIKI quote:- "Like the Midrash and the Talmud, the Targum does not think of a globe of the spherical earth, around which the sun revolves in 24 hours, but of a flat disk of the earth,


ROFL, we were talking of scientific textbooks, not religious scripture.

And as for flying off the planet, you are once again quoting an "effect" not a proof, which can be explained in several ways without inventing "Gravity".


The "effect" is what is called "gravity", you just need to learn the jargon.

Please, have a final rant if you must ..


No thanks, you're doing fine by yourself.