Is inflation theory falsifiable?

[Michael]

Not only have the results from the lab and from space been rather "unkind" to the dark matter hypothesis, we're also seeing a rebellion taking place with respect to inflation theory between the old guard and a younger generation of theoriests. Keep in mind that there are hundreds of variations of inflation theory to choose from, not just one.

Cosmic Inflation Theory Faces Challenges

Some scientists accept that inflation is untestable but refuse to abandon it. They have proposed that, instead, science must change by discarding one of its defining properties: empirical testability. This notion has triggered a roller coaster of discussions about the nature of science and its possible redefinition, promoting the idea of some kind of nonempirical science.

A common misconception is that experiments can be used to falsify a theory. In practice, a failing theory gets increasingly immunized against experiment by attempts to patch it. The theory becomes more highly tuned and arcane to fit new observations until it reaches a state where its explanatory power diminishes to the point that it is no longer pursued. The explanatory power of a theory is measured by the set of possibilities it excludes. More immunization means less exclusion and less power. A theory like the multimess does not exclude anything and, hence, has zero power. Declaring an empty theory as the unquestioned standard view requires some sort of assurance outside of science. Short of a professed oracle, the only alternative is to invoke authorities. History teaches us that this is the wrong road to take.

This article from earlier this year is of course controversial. It was rebutted recently by a group that includes Alan Guth and Andrei Linde. Some of the commentary of their rebuttal is pretty amusing IMO:

A Cosmic Controversy

Their first argument is simply an obvious appeal to popularity fallacy combined with an appeal to authority fallacy even though as the original authors pointed out, history teaches us that this is the wrong road to take:

There is no disputing the fact that inflation has become the dominant paradigm in cosmology. Many scientists from around the world have been hard at work for years investigating models of cosmic inflation and comparing these predictions with empirical observations. According to the high-energy physics database INSPIRE, there are now more than 14,000 papers in the scientific literature, written by over 9,000 distinct scientists, that use the word “inflation” or “inflationary” in their titles or abstracts. By claiming that inflationary cosmology lies outside the scientific method, IS&L are dismissing the research of not only all the authors of this letter but also that of a substantial contingent of the scientific community.

So what if there is a lot of literature written about inflation theory over the past three decades? Over 200 authors signed their name to that BICEP2 fiasco paper too before it turned to dust. It's not like a large group of individuals cannot all be wrong. In science there really is no safety in numbers. It's telling IMO that their first argument in an appeal to authority/popularity fallacy.

It should be noted that Guth listed three major "predictions" about inflation that have all since either been proven to be wrong, or that never had any real predictive usefulness in the first place.

When first proposing inflation theory, Guth claimed that inflation 'explained' why monopoles do not exist, which is essentially like claiming that your new theory about bigfoot "explains" why unicorns do not exist because bigfoot ate them all. He also claimed that inflation explained why the universe is "flat", but Penrose later demonstrated that the universe is 10 to the 100th power *less* likely to be flat with inflation than without it, making that "prediction" rather self destructive and self defeating in the final analysis. Guth also claimed that inflation ensures that the universe is homogeneous even at the largest scales, yet the Planck data has shown that there are hemispheric variations that defy those predictions too.

ESA Science & Technology: Simple but challenging: the Universe according to Planck

I also just love the tu-quo fallacy Guth et all resorted to next:

They contend, for example, that inflation is untestable because its predictions can be changed by varying the shape of the inflationary energy density curve or the initial conditions. But the testability of a theory in no way requires that all its predictions be independent of the choice of parameters. If such parameter independence were required, then we would also have to question the status of the Standard Model, with its empirically determined particle content and 19 or more empirically determined parameters.

So basically their argument amounts to a tu-quoque fallacy. The big bang theory requires similar "fine tuning" with respect to the amount of dark matter and dark energy, etc, so of course inflation theory should be able to be "fine tuned" too. In other words, none of their cosmology "predictions" work without setting all the initial conditions exactly right, so inflation theory should get a free pass on that score too. That's not a strong argument for inflation, it's a strong argument against the whole BB paradigm IMO.

While Guth et all talk about various "predictions" and "testing' of inflation over the years, they're basically ignoring several key points which were addressed very nicely by the original authors in their rebuttal letter:

Inflation is highly sensitive to initial conditions that are not yet understood, as the respondents concede, the outcome cannot be determined. And if inflation produces a multiverse in which, to quote a previous statement from one of the responding authors (Guth), “anything that can happen will happen”—it makes no sense whatsoever to talk about predictions. Unlike the Standard Model, even after fixing all the parameters, any inflationary model gives an infinite diversity of outcomes with none preferred over any other. This makes inflation immune from any observational test. For more details, see our 2014 paper “Inflationary Schism” (preprint available at https://arxiv.org/abs/1402.6980).

The multiverse scenario allows for pretty much *any* type of universe, and the only thing that really differentiates between them are the initial conditions which can be modified to come up with just about anything and everything.

The "bogus" claim of making "testable predictions' is best exemplified by this statement IMO:

The situation is similar to the standard hot big bang cosmology: the fact that it left several questions unresolved, such as the near-critical mass density and the origin of structure (which are solved elegantly by inflation), does not undermine its many successful predictions, including its prediction of the relative abundances of light chemical elements. The fact that our knowledge of the universe is still incomplete is absolutely no reason to ignore the impressive empirical success of the standard inflationary models.

The "predictions" related to the relative abundances of light elements is entirely dependent upon the existence of "exotic" forms of matter, otherwise that "prediction" doesn't work right. In essence it's not *just* inflation that you need, you need *two* supernatural entities, both inflation *and* dark matter to get that "prediction' to pan out properly. It's not even a "prediction" of inflation by itself!

The whole notion of "testing' inflation ends up requiring *faith* in more than one supernatural construct, but rather relies upon *several* such constructs which pretty much blows their claims about 'testing' and "predictions" right out of the water.

As that Planck article points out:

At the same time, the extraordinary quality of the Planck data reveals the presence of subtle anomalies in the CMB pattern that might challenge the very foundations of cosmology. The most serious anomaly is a deficit in the signal at large angular scales on the sky, which is about ten per cent weaker than the standard model would like it to be. Other anomalous traits that had been hinted at in the past - a significant discrepancy of the CMB signal as observed in the two opposite hemispheres of the sky and an abnormally large 'cold spot' - are confirmed with high confidence. Planck's new image of the CMB suggests that some aspects of the standard model of cosmology may need a rethink, raising the possibility that the fabric of the cosmos, on the largest scales of the observable Universe, might be more complex than we think.

So even when we include *four* different processes/entities which fail to show up in the lab, we're still left with observations that defy the "predictions' made by the BB model. How exactly then can inflation theory be falsified?

 

[Halbhh]

I noticed this: "...Penrose later demonstrated that the universe is 10 to the 100th power *less* likely to be flat with inflation...."

I hadn't seen that, but it immediately brought up stuff I've read in the last year about how the Higgs Boson mass is so fine-tuned in a seemingly unnatural way (not elegantly explainable, but just looks unnatural) due the lack of the accompanying particles that were expected to be found at CERN's LHC to explain its mass, but *are not there*. But, because of the inexplicably (so far that is) perfectly balanced forces, our Universe as we know it can exist. It did not quickly collapse, nor quickly move into runaway expansion and quick entropy death.

The only way at the moment to come up with an explanation for the Higgs mass -- which might make sense as for example a particular chance occurrence among 10^500 variations for example -- after the failure to find expected other particles, is to posit some kind of totally untestable -- and likely could never be tested, ever -- multiverse theory, of which there are already a variety of incompatible hypotheses, all untestable.

 

[Halbhh]

As I read more, I can see you've done some reading, and one thought to offer -- this is still an area of exploration, and lots of hypothesis. They are trying to find their way in the dark. It's not reflective of bad physics, usually, but just of exploration.

But....having read articles for decades, it doesn't look to me even slightly like we are likely to have a completion of the enterprise of fundamental physics anytime soon, meaning decades. Most people only read popular science articles of course, and they are totally unaware that in physics *most* of reality is not understood.

 

[Halbhh]

One more connection point -- cosmology is merely physics in action, and that means fundamental physics in action, i.e. 'high energy physics' or 'particle physics'. In other words all the thinking around particle physics is about the same essential questions as these big questions in cosmology you are pointing out, and the Universe as we observe it is a big particle physics machine. Cosmology is more fun to read about of course.

 

[CrystalDragon]

I think it is falisifiable, personally.

If my memory serves me correctly, scientists observe how far away galaxies are using the redshift-blueshift of the Doppler effect, similar to how when a car passes by the noise of the engine seems to grow in pitch as it reaches you before lowering in pitch as it passes. If the rate of redshift when it comes to galaxies seems to be speeding up, then inflation theory is plausible. If the Doppler shift does not support it, then it's falsified.

 

[Paul of Eugene OR]

Not only have the results from the lab and from space been rather "unkind" to the dark matter hypothesis, we're also seeing a rebellion taking place with respect to inflation theory between the old guard and a younger generation of theoriests. Keep in mind that there are hundreds of variations of inflation theory to choose from, not just one.

Cosmic Inflation Theory Faces Challenges



This article from earlier this year is of course controversial. It was rebutted recently by a group that includes Alan Guth and Andrei Linde. Some of the commentary of their rebuttal is pretty amusing IMO:

A Cosmic Controversy

Their first argument is simply an obvious appeal to popularity fallacy combined with an appeal to authority fallacy even though as the original authors pointed out, history teaches us that this is the wrong road to take:



So what if there is a lot of literature written about inflation theory over the past three decades? Over 200 authors signed their name to that BICEP2 fiasco paper too before it turned to dust. It's not like a large group of individuals cannot all be wrong. In science there really is no safety in numbers. It's telling IMO that their first argument in an appeal to authority/popularity fallacy.

It should be noted that Guth listed three major "predictions" about inflation that have all since either been proven to be wrong, or that never had any real predictive usefulness in the first place.

When first proposing inflation theory, Guth claimed that inflation 'explained' why monopoles to not exist, which is essentially like claiming that your new theory about bigfoot "explains" why unicorns do not exist because bigfoot ate them all. He also claimed that inflation explained why the universe is "flat", but Penrose later demonstrated that the universe is 10 to the 100th power *less* likely to be flat with inflation than without it, making that "prediction" rather self destructive and self defeating in the final analysis. Guth also claimed that inflation ensures that the universe is homogeneous even at the largest scales, yet the Planck data has shown that there are hemispheric variations that defy those predictions too.

ESA Science & Technology: Simple but challenging: the Universe according to Planck

I also just love the tu-quo fallacy Guth et all resorted to next:



So basically their argument amounts to a tu-quoque fallacy. The big bang theory requires similar "fine tuning" with respect to the amount of dark matter and dark energy, etc, so of course inflation theory should be able to be "fine tuned" too. In other words, none of their cosmology "predictions" work without setting all the initial conditions exactly right, so inflation theory should get a free pass on that score too. That's not a strong argument for inflation, it's a strong argument against the whole BB paradigm IMO.

While Guth et all talk about various "predictions" and "testing' of inflation over the years, they're basically ignoring several key points which were addressed very nicely by the original authors in their rebuttal letter:



The multiverse scenario allows for pretty much *any* type of universe, and the only thing that really differentiates between them are the initial conditions which can be modified to come up with just about anything and everything.

The "bogus" claim of making "testable predictions' is best exemplified by this statement IMO:



The "predictions" related to the relative abundances of light elements is entirely dependent upon the existence of "exotic" forms of matter, otherwise that "prediction" doesn't work right. In essence it's not *just* inflation that you need, you need *two* supernatural entities, both inflation *and* dark matter to get that "prediction' to pan out properly. It's not even a "prediction" of inflation by itself!

The whole notion of "testing' inflation ends up requiring *faith* in more than one supernatural construct, but rather relies upon *several* such constructs which pretty much blows their claims about 'testing' and "predictions" right out of the water.

As that Planck article points out:



So even when we include *four* different processes/entities which fail to show up in the lab, we're still left with observations that defy the "predictions' made by the BB model. How exactly then can inflation theory be falsified?

Relax, its going to either pan out or not pan out, and that will be based on the evidence.

 

[Halbhh]

Relax, its going to either pan out or not pan out, and that will be based on the evidence.

Actually, it's starting to look (and I say this after about 35 years of reading in the field) like it's not going to pan out. I mean anything in some of these questions, even any final result or completed theory of everything.

Lots of things will pan out.

Fundamental physics -- not so sure.

We are beginning to see a possibility in physics that there may be real limits we cannot get past because key hypotheses won't be possible to test or observe in any way. Possibly ever, as other universes in a multiverse theory seem they would be unobservable, forever. (or at least in this mortal life)

 

[Michael]

Relax, its going to either pan out or not pan out, and that will be based on the evidence.

Will that happen in my lifetime?

 

[Michael]

I think it is falisifiable, personally.

If my memory serves me correctly, scientists observe how far away galaxies are using the redshift-blueshift of the Doppler effect, similar to how when a car passes by the noise of the engine seems to grow in pitch as it reaches you before lowering in pitch as it passes. If the rate of redshift when it comes to galaxies seems to be speeding up, then inflation theory is plausible. If the Doppler shift does not support it, then it's falsified.

Doppler shift is related to *moving objects* whereas LCDM theory requires something very different, namely 'space expansion' to explain redshift. Doppler shift happens in the lab because objects move in the lab. Space expansion is an act of faith which does not occur in any lab on Earth, inside this solar system, or even inside our galaxy or galaxy cluster.

Technically redshift and space expansion can occur *without* inflation, so that's not really a 'test' of the inflation theory itself.

Keep in mind that there are even other (empirical) ways to explain photon redshift/distance, starting with various types of inelastic scattering, so even "space expansion" isn't really the only explanation for photon redshift.

 

[Michael]

I noticed this: "...Penrose later demonstrated that the universe is 10 to the 100th power *less* likely to be flat with inflation...."

Inflation (cosmology) - Wikipedia

Other configurations lead to a uniform, flat universe directly – without inflation. Obtaining a flat universe is unlikely overall. Penrose's shocking conclusion, though, was that obtaining a flat universe without inflation is much more likely than with inflation – by a factor of 10 to the googol (10 to the 100) power!"[4][111]

I hadn't seen that, but it immediately brought up stuff I've read in the last year about how the Higgs Boson mass is so fine-tuned in a seemingly unnatural way (not elegantly explainable, but just looks unnatural) due the lack of the accompanying particles that were expected to be found at CERN's LHC to explain its mass, but *are not there*.

Ya, SUSY theory was expected to explain everything from the fine tuning problems of particle physics theory to the dark matter claims of LCDM theory, but unfortunately LHC seems to have ruled out SUSY theory, or at least LHC has falsified all of it's key "predictions".

But, because of the inexplicably (so far that is) perfectly balanced forces, our Universe as we know it can exist. It did not quickly collapse, nor quickly move into runaway expansion and quick entropy death.

Those runaway expansion ideas typically relate back to Multiverse (multimess ) theories, and the stability of our own universe seems to undermine that notion which seems like another good reason to dump inflation theory.

The only way at the moment to come up with an explanation for the Higgs mass -- which might make sense as for example a particular chance occurrence among 10^500 variations for example -- after the failure to find expected other particles, is to posit some kind of totally untestable -- and likely could never be tested, ever -- multiverse theory, of which there are already a variety of incompatible hypotheses, all untestable.

It seems to me that particle physics theories in general are more "testable" than cosmology claim in general. Nothing like inflation, or space expansion, or 'dark energy' shows up in a lab. Only the dark matter claim of LCD can really be tested in controlled experiments, and that's been a complete bust to date.

I don't really believe that the inflation hypothesis, the space expansion hypothesis, or the dark energy hypothesis are actually falsifiable claims. You either believe in those ideas individually or collectively, or your don't, but the "belief" position (vs. lack of belief) requires an original "act of faith" in the concept, and in the "effects" that are hypothetically caused by the concept. That puts it way too squarely into the realm of "religion" for my tastes. I'm a fan of empirical testable physics, but the unfalsifiable realm of physics just seems as goofy to me as Scientology.

 

[Michael]

One more connection point -- cosmology is merely physics in action, and that means fundamental physics in action, i.e. 'high energy physics' or 'particle physics'. In other words all the thinking around particle physics is about the same essential questions as these big questions in cosmology you are pointing out, and the Universe as we observe it is a big particle physics machine. Cosmology is more fun to read about of course.

Cosmology theories tends to be more fun to write about too, particularly since it's less limited or constrained by empirical physical ideas or data. Particle physics hypotheses also tend to be more prone to falsification in the lab as SUSY proponents have discovered.

 

[Paul of Eugene OR]

Will that happen in my lifetime?

What is certain is that there will be scientific mysteries, if not that one, all of your life.

 

[Halbhh]

For many people, even those habitually reading articles, the wikis on the Cosmological Constant and on the Lambda-CDM model are pretty well written, and help lay out the big picture situation of the moment, making a few connections of use (one needn't read the piece with all the math unless that's your thing). One can start with the brief Cosmological Constant wiki, and then click the link to a nice overview of the Lambda-CDM model. I like all the embedded links one can get quick overviews on.

 

[Michael]

What is certain is that there will be scientific mysteries, if not that one, all of your life.

Well, as others have pointed out, inflation doesn't seem to be panning out all that well thus far after 35 years and counting, and there are other cosmology theories that don't require me to hold faith in inflation theory.

Some mysteries seem rather inevitable, but this particular one seems to be pointless as well as lacking in falsification potential.

 

[Michael]

FYI, here is the "longer" (complete) rebuttal to Guth's response for anyone who's interested.

Pop Goes the Universe

It should be noted that I originally assumed in my opening comments that Guth comments about fine tuning were referring to the standard cosmology model rather than the standard particle physics model, but the authors address that point quite well.

 

[Halbhh]

Well, since I read carefully, and often follow links to get more, and check on things I don't know, it could take a while for me to follow up all of these links you offer.

But I can offer you a distillation from many hundreds of articles up on the level of phys.org and scientific american and similar sites about 'dark matter' that may be informative.

"Dark Matter" (CDM for 'cold dark matter') is simply a generic style name for what isn't yet understood -- what stuff/thing/force is causing Galaxies to clearly and unambiguously rotate in a very odd way with areas far from the centers orbiting *much faster* than they should just from ordinary gravitation from ordinary matter.

Galaxies do *not* act like our own solar system, with orbital velocities falling off with distance from the center of mass according to Newton's approximation.

They rotate much faster out on the edges than the known matter in them -- gas, stars, dust, collapsed stars -- can account for.

Thus "dark matter" -- the unknown that is causing this odd rotation in galaxies.

It's not a unsupported notion -- rather it's an *unknown cause* for a clear and sharply unambiguous and repeated observation.

Exactly the same is true for gravitational lensing via galaxies -- they bend light more than they can just from the ordinary matter they have in them; and in the grouping of galaxies -- they group together more/sooner than they should from mutual gravitation just from ordinary matter.

Something is causing extra gravitation, and we don't know what it is.

 

[Michael]

Well, since I read carefully, and often follow links to get more, and check on things I don't know, it could take a while for me to follow up all of these links you offer.

But I can offer you a distillation from many hundreds of articles up on the level of phys.org and scientific american and similar sites about 'dark matter' that may be informative.

"Dark Matter" (CDM for 'cold dark matter') is simply a generic style name for what isn't yet understood -- what stuff/thing/force is causing Galaxies to clearly and unambiguously rotate in a very odd way with areas far from the centers orbiting *much faster* than they should just from ordinary gravitation from ordinary matter.

Galaxies do *not* act like our own solar system, with orbital velocities falling off with distance from the center of mass according to Newton's approximation.

They rotate much faster out on the edges than the known matter in them -- gas, stars, dust, collapsed stars -- can account for.

Thus "dark matter" -- the unknown that is causing this odd rotation in galaxies.

It's not a unsupported notion -- rather it's an *unknown cause* for a clear and sharply unambiguous and repeated observation.

Exactly the same is true for gravitational lensing via galaxies -- they bend light more than they can just from the ordinary matter they have in them; and in the grouping of galaxies -- they group together more/sooner than they should from mutual gravitation just from ordinary matter.

Something is causing extra gravitation, and we don't know what it is.

Galaxy’s hydrogen halo hides missing mass

Keep in mind that this most recent finding of ordinary baryonic matter that is composed of ordinary hydrogen gas, which has been "hiding" from us until just this year, is in *addition to* at least five other major mass calculations mistakes that we've been making up through 2006 when the infamous "proof of dark matter" paper was published.

Thunderbolts Forum • View topic - Lambda-CDM - EU/PC Theory - Confirmation Bias

I'm certainly inclined to believe that our baryonic mass calculations which are based upon light are pitifully flawed in numerous ways, but I have no evidence whatsoever to suggest that mainstream baryonic mass estimates of galaxies were ever correct, or that exotic forms of matter exist in nature.

DM is probably the *only* concept of LCDM theory that actually can be put to the test in the lab, and it's be a *dismal failure* in terms of it's predictive usefulness. When is dead horse a dead horse? What evidence is there that our baryonic mass estimates of galaxies, including our own, were ever correct to start with?

 

[Halbhh]

Ok, but before I go a lot further, the calculated ratio of the missing mass, which is straightforward, says that missing mass, the "dark matter" is.... 63% of the total mass needed for the observed gravitation.

That's a big factor, so finding Jupiters floating around interstellar space, lots of brown dwarfs, sure, they could add up, but it's a factor of 5 to make up vs ordinary matter, so it's going to be interesting....

 

[Michael]

Ok, but before I go a lot further, the calculated ratio of the missing mass, which is straightforward, says that missing mass, the "dark matter" is.... 63% of the total mass needed for the observed gravitation.

That's a big factor, so finding Jupiters floating around interstellar space, lots of brown dwarfs, sure, they could add up, but it's a factor of 5 to make up vs ordinary matter, so it's going to be interesting....

It sure sounds like a lot of missing mass until you realize that the mainstream has been underestimating the number of stars in galaxies by somewhere between 3 and 20 times depending on the size of the star and the type of galaxy and they've been underestimating the number of stars between galaxies that are shared by the clusters.

NASA - Galaxies Demand a Stellar Recount
Scientists Find 200 Sextillion More Stars in the Sky
A Universe of Stars May Exist Outside Galaxies | RealClearScience

Stars are spaced so far apart that they wouldn't likely "collide" in a galaxy collision, they'd simply pass right on through just like "dark matter". We don't need any brown dwarf mass to explain any of that missing matter because they've been radically underestimating the number of entire stars in galaxies since day one.

The bottom line is that the mainstream's mass estimation techniques that were used in that 2006 study were absurdly flawed, horrifically flawed and outrageously flawed in nearly every conceivable way.

It's also noteworthy that since 2012 we've also found out that every galaxy is surrounded by a halo of hot plasma as well as a halo of uncharged hydrogen particles too which contain more mass than all the stars combined!

Milky Way is Surrounded by Huge Halo of Hot Gas | ChandraBlog | Fresh Chandra News
Galaxy’s hydrogen halo hides missing mass

The baryonic mass estimates that are being used by the mainstream are simply not worth the paper they are printed on. They're worthless.

 

[Halbhh]

Ok, but the first 2 news about finding more stars I remember quite well, and as you can see the dates are about 7 years back, and of course, we ought to be able to expect the ratio to dark matter was modified back then...
About the 3rd on rouge stars *outside* galaxies -- those have zero effect on orbital velocities inside galaxies on averaging (ask me if you need more info for that, my degree is in engineering physics, but astrophysics is a long time hobby interest, and using many principles we learned in freshman physics).
The same principle applies to halos of gas *outside* the radius of the orbiting stars traveling at the higher than accountable for velocity. The principle is simple -- it's the mass (normal matter and other) inside the radius of the orbit that causes the orbital velocity (on average). (Though some other interesting (and intuitive) effects happen on star velocities, like being pulled faster or slower by a higher density area nearby like a nearby spiral arm.)

But the last link is the most interesting. Note these key sentences:
"The suggestion of a massive hydrogen halo arose among astronomers to explain an apparent discrepancy in the ratio of conventional, or “baryonic”, matter to dark matter in the Milky Way.

"Using widely accepted proportions of dark to baryonic matter, set against the calculated mass of the entire system, the observed baryonic portion came up light – missing about 50 per cent of the heft the calculations require."
...
and the essential summary points:

“You don’t just see a pretty picture of a halo around a galaxy,” Zaritsky says.

“We infer the presence of galactic halos from numerical simulations of galaxies and from what we know about how they form and interact.”

"Based on such simulations, scientists predicted the presence of large amounts of hydrogen gas just hanging around the Milky Way.

"Drilling through the data, Zaritsky and Zhang confirmed not only the existence of the gas, but also that its mass matches that missing in the baryonic-to-dark-matter equation."

See? They are only tidying up to find the expected normal matter to fit the ratio generally expected where the normal matter is about 1/5 of the dark matter....

No change there. It's the status quo. Dark matter = about 5 times normal matter.