Comments about the article in Nature: "Defend the integrity of Physics"

Following is a discussion about this article in Nature News Vol 516 18/25 December 2014, by George Ellis and Joe Silk
To read the article select:
In the last paragraph I explain my own opinion.


The article starts with the sentence:
Attempts to exempt speculatieve theories of the Universe from experimental verification undermine science argue George Ellis and Joe Silk.
Any theory to be a "honest" physical theory should have the quality or be based that its predictions in someway can be verified. See also reflection 1 Next we read:
They began to argue, that if a theory is sufficiently elegant and explanatory, it need not be tested experimentally,
See reflection 1 . It is not strictly required that the full theory should be based on experiments but the theory should be clear that the individual cause and effects relations should be unequivocal lead to what is observed.
For example the Big Bang theory can not experimental tested.
Chief among the 'elegance will suffice' advocates are some string theorists.
To understand (agree) with this sentence you must understand the concept of string theory, otherwise your argumentation becomes flaky.
A theory which is flaky can never be verified
Because string theory is supposedly the 'only game in town' capable of unifying the four fundamental forces, they believe that it must contain a grain of truth even though it relies on extra dimensions that we can never observe.
Also here using the concept of extra dimensions (which is not explained) makes the sentence flaky.
It should be mentioned that our unverse is based on 3 dimensions i.e. a cordinate system in three directions. Using that system we can define a position in space for each object.
The individual dimensions can not be observed.
Some cosmologists, too, are seeking to abandon experimental verification of grand hypotheses that invoke imperceptible domains such as the kaleidoscopic multiverse, the 'many worlds' version of quantum reality and pre-Big Bang concepts.
All of physics that has to do with the total universe should be considered with care.
These unprovable hypotheses are quite different from those that relate directly to the real world and that are testable through observations — such as the standard model of particle physics and the existence of dark matter and dark energy.
As we see it, theoretical physics risks becoming a no-man's-land between mathematics, physics and philosophy that does not truly meet the requirements of any.
To compare the three concepts mathematics, physics and phylosophy in one sentence has to be done with care.
In March, theorist Paul Steinhardt wrote in this journal that the theory of inflationary cosmology is no longer scientific because it is so flexible that it can accommodate any observational result.
For Comments about this article select: Big Bang blunder bursts the multiverse bubble
In a sense Paul Steinhardt is correct. IMO it is worse: All of what is happening before and after the Big Bang should be investigated with care.
You could postulate a certain sequence of processes that took place in the early universe which explain what is observed but that does not mean they actual happened.
This battle for the heart and soul of physics is opening up at a time when scientific results — in topics from climate change to the theory of evolution — are being questioned by some politicians and religious fundamentalists.
That is why we should study physics very rigorous i.e based on facts, observations and experimental results.
The same issues are also at stake when you consider astrology and homeopathie.
When people explain homeopatie using the quantum theory you walk on an icy road.
See for example: Towards a Quantum Mechanical Interpretation of Homeopathy

String theory

String theory is an elaborate proposal for how minuscule strings (one-dimensional space entities) and membranes (higher-dimensional extensions) existing in higher-dimensional spaces underlie all of physics.
As soon as when one-dimensional entities and higher-dimensional extensions become involved physical science becomes flaky.
Some aspects of string theory can be tested experimentally in principle.
For example, a hypothesized symmetry between fermions and bosons central to string theory — supersymmetry — predicts that each kind of particle has an as-yet-unseen partner.
The issue that a fermion has a partner does not verify string theory.
The explanation as such (if confirmed by observation) could be completely different.
Dawid argues that the veracity of string theory can be established through philosophical and probabilistic arguments about the research process.
Science has nothing to do with both arguments.
Because “no-one has found a good alternative” and “theories without alternatives tended to be viable in the past”, he reasons that string theory should be taken to be valid.
I think you need more.
In our opinion, this is moving the goalposts. Instead of belief in a scientific theory increasing when observational evidence arises to support it, he suggests that theoretical discoveries bolster belief.
Unfortunate this sentence is not clear.
But conclusions arising logically from mathematics need not apply to the real world.
You can use mathematics in order to support physical science. You cannot

Many Multiverses

The multiverse is motivated by a puzzle:
why fundamental constants of nature, such as the fine-structure constant that characterizes the strength of electromagnetic interactions between particles and the cosmological constant associated with the acceleration of the expansion of the Universe, have values that lie in the small range that allows life to exist.
The fact that life has exists has nothing to do nor can explained by multiverses.
The problem is that this sentence tries to combine many concepts which have nothing to do with each other. In fact you mix mathematics (ratios) with physics.
Multiverse theory claims that there are billions of unobservable sister universes out there in which all possible values of these constants can occur.
When you read this sentence the Multiverse theory has lost reality.
What would be "simpler" if the Multiverse theory claims that in each Universe the cosmological parameters of the friedmann equation are different. (This implies different lambda values but does not say anything about electromagnetic interactions.) The problem is why does one makes such a claim which cannot be tested.
The next most important question to answer is to give a general description of the processes involved after the Big Bang to create all these universes.
Earlier this year, championing the multiverse and the many-worlds hypothesis, Carroll dismissed Popper's falsifiability criterion as a “blunt instrument” (see Edge Organisation Falsifiability by Sean Carroll )
See: reflection part 2 - Sean Carroll IMO Sean Carroll is not the most appropiate person to evaluate what the relation between physics, multiverse and many-worlds should be, because of on his own involvment in these fields.
He offered two other requirements: a scientific theory should be “definite” and “empirical”.
By “definite”, Carroll means that the theory says “something clear and unambiguous about how reality functions”.
That is correct. The problem is that the MUltiverse theory does not do that. The Multiverse theory is not clear.
By “empirical”, he agrees with the customary definition that a theory should be judged a success or failure by its ability to explain the data.
He should have added: "to explain the observations unambiguous".
The problem is that the MUltiverse theory does not do that. The Multiverse theory is not clear and is not based on observations.
Some people have devised forms of multiverse theory that are susceptible to tests: physicist Leonard Susskind's version can be falsified if negative spatial curvature of the Universe is ever demonstrated.
The problem is how do you perform so a test? He falls in the same trap as the others.
Exactly what is: "negative spatial curvature"?
The many-worlds theory of quantum reality posed by physicist Hugh Everett is the ultimate quantum multiverse, where quantum probabilities affect the macroscopic.
Immediate when you start using a concept like quantum probabilities which is unclear (What are quantum probabilities? Quantum probabilities of what? What are these relations?) this how sentence becomes speculation. The worst is it is impossible to agree or disagree with this sentence because it is unclear.
In our view, cosmologists should heed mathematician David Hilbert's warning: although infinity is needed to complete mathematics, it occurs nowhere in the physical Universe.
I think it is not that simple.

Pass the test

We agree with theoretical physicist Sabine Hossenfelder: post-empirical science is an oxymoron (see Post-empirical science is an oxymoron. and Scientia Salon String theory and post-empiricism ).
For comments see: reflection part 3 - Sabine Hossenfelder
Theories such as quantum mechanics and relativity turned out well because they made predictions that survived testing.
The authors should be more specific to make these claims. I do not think that all of quantum mechanics is what you can call rock bottom science
The consequences of overclaiming the significance of certain theories are profound — the scientific method is at stake (see Scientia Salon What is science and why should we care? — Part I by Alan Sokal).
For comments see: reflection part 4 - Alan Sokal
Physicists, philosophers and other scientists should hammer out a new narrative for the scientific method that can deal with the scope of modern physics.
There exists not something as modern physics.
In our view, the issue boils down to clarifying one question: what potential observational or experimental evidence is there that would persuade you that the theory is wrong and lead you to abandoning it?
Physicists when they have a new theory should give enough evidence that the theory is correct.
That means they should predict the outcome before the experiment is done.
A theory is not by definition wrong when you try to repeat the same experiment and you cannot succeed.

Reflection part 1 - General

The “integrity of physics document” discusses a very important issue. What we all want is rock bottom science based on observations and experiments. The problem is that is not what often is happening. The main reason is to perform science or to do physical experiments, is becoming much more difficult specific on your own. The time of Pierre and Irčne Curie, who almost worked alone, is long gone.
The problem already started with the quantum theory. Consider me and you the reader in different rooms separated by a door. We are both asked to place either a red or a green hat on and knock on the door when ready. When I hear you knocking I will proclaim that you are in a state of both red and green. This is a simpler version of the “Schrodinger Cat paradox” where the cat is both alive and dead. Is this rock bottom science? I doubt it. Human observations have nothing to do with the evolution(behavior) of physical processes. As such to call a Black-hole black is also misleading.
Special Relativity discusses two subjects: Time Dilution and Length Contraction.
Time Dilution is a physical concept which involves that a moving clock runs slower and can be experimentally demonstrated. A stays at home and B steps in an airplane and makes one round trip around the earth. After B returns and compares his clock with the clock of A he will conclude that his clock did run slower during the duration of the flight. Does this mean that the age of the Universe after they return is different? No. In fact the moving clock of B shows the wrong “Universal” time.
Length Contraction is a much more difficult physical concept to demonstrate. It means that the length of a moving object becomes shorter. To demonstrate no moving clocks should be involved. The simplest demonstration is to place two lamps, one before and one after a “train”. The observer is in the middle. When the observer observes both signals simultaneous when the train is in between the lamps there is length contraction involved. As far as I know no such experiment has ever been performed.
The importance of Newton’s Law is that based on actual observations we can predict the future and observe that these predictions are correct. That is what science is all about. The problem is that this law fails when you try to calculate the trajectory of the planet Mercury. The reason is because Newton’s Law is based on forces. The direction of these forces is straight towards the center of the masses and assume instantaneous action. In reality this is not the case. When you assume that the actions take time to propagate the accuracy of your predictions increase.
One of the most interesting experiments is the Miller Urey experiment “that simulated the conditions thought at the time to be present on the early Earth, and tested the chemical origin of life.” (See Wikipedia)
To demonstrate the Big Bang, specific the inflation theory, no such similar tests are within reach. The inflation theory involves a very vast expansion of the universe. The specific chemical processes involved are not known nor can this expansion process being tested. When we perform astronomical observations we observe (the state of) the past. Of the universe at present (which has a supposed size of roughly 3 times the distance that light will travel since the Big Bang) we can observe “nothing”. The furthest galaxies we can observe are in a much more infant state.
The furthest we can observe is the Microwave Background radiation which gives us an image of the Universe 380000 years after the Big Bang. The CMB radiation (measured at present) shows a very uniform density distribution of a sphere centered around us. Does that mean that all inside this sphere 380000 after the BB also had an uniform density? And all outside? Most probably not. The assumption that the Universe at present is homogeneous and isotropic makes everything much simpler but is not based on observations.
The physical state of the universe short after the BB is influenced by two concepts: Acoustic waves and gravitational waves Both concept should leave an image in the CMB radiation. The Acoustic waves in the power spectrum and the gravitational waves in the polarization. None of the processes involved are clear. The fact that you can calculate a power spectrum at present is no proof that there are Acoustic waves in the past. The same for polarization versus gravitational waves.
The multiverse universe concept assumes that in connection with the inflation period multiple universes popped up into existence. What that means is that the total of all these universes, at present, is highly inhomogeneous and anisotropic. All these universes should be behind of the rim of what we now call our universe. The most logical assumption is that all these universes are described by the same laws as our universe implying at least that they have the same periodic table and the same subatomic particles (quarks). To assume that these universe are all different in that aspect, compared to our universe, is pure speculation and does not agree with the concept of rock bottom science.
To assume that there are more universes like ours which all, more or less, followed the “same” evolution path , makes sense . The problem the more we go back to the time of the Big Bang the more insecure we become of what happened. We all have different opinions about that because nobody knows for sure. For the state of the BB there are almost two opposite point of views. Either the BB started from a very organized high energy density state or the BB started from nothing creating a universe which consists of particles and its anti-particles. The sad part is that almost nothing can be tested in this realm, but it is no nonsense.

Reflection part 2 - Sean Carroll

Sean Carroll writes:
By "definite" we simply mean that they say something clear and unambiguous about how reality functions.
String theory says that, in certain regions of parameter space, ordinary particles behave as loops or segments of one-dimensional strings. The relevant parameter space might be inaccessible to us, but it is part of the theory that cannot be avoided.
This sentence is clearly not unambiguous.
What means: "in certain regions of parameter space"?
In the cosmological multiverse, regions unlike our own are unambiguously there, even if we can't reach them.
The very use of the word "unambiguously" make the whole sentence unclear or ambiguous.
Consider the multiverse. It is often invoked as a potential solution to some of the fine-tuning problems of contemporary cosmology. For example, we believe there is a small but nonzero vacuum energy inherent in empty space itself. This is the leading theory to explain the observed acceleration of the universe,
This may be true but acceleration has no relation with the multiverse theory.
The acceleration of the universe is not by vissible means observed. It is calculated based on observations and by using a model.

Reflection part 3 Sabine Hossenfelder

This Blog starts with the text:
Richard Dawid argues that physics, or at least parts of it, are about to enter an era of post-empirical science. By this he means that “theory confirmation” in physics will increasingly be sought by means other than observational evidence because it has become very hard to experimentally test new theories.
The last is correct but that does not mean that no observational evidence is required. It is a must
Anyway most theories start with different observations. The theory than describes the relations between those observations which are not known. The theory often describes how does relations can be modified and what the outcome will be. The theory is demonstrated to be true when these newly predicted observations are actually observed.

For further reading see: String theory and post-empiricism In this article Richard Dawid is interviewed by Richard Marshall
It is clear that Richard Dawid is not the most appropiate person to evaluate what the relation between physics and string theory should be, because of on his own involvement is string theory.

Reflection part 4 Alan Sokal

What is science and why should we care? — Part I

Thus, by science I mean, first of all, a worldview giving primacy to reason and observation and a methodology aimed at acquiring accurate knowledge of the natural and social world.
Accepted. The discussion is here about natural world.
The extraordinary successes of the natural sciences over the last 400 years in learning about the world, from quarks to quasars and everything in-between, are well known to every modern citizen: science is a fallible yet enormously successful method for obtaining objective (albeit approximate and incomplete) knowledge of the natural (and to a lesser extent, the social) world.
But, surprisingly, not everyone accepts this; etc.
Such people insist that so-called scientific knowledge does not in fact constitute objective knowledge of a reality external to ourselves, but is a mere social construction, on a par with myths and religions, which therefore have an equal claim to validity.
IMO physical problems and social problems have both an equal claim to validity.
This implies that what they claim should be clear and testable. The problem is that in many social problems related to human behavior this is not the case.
IMO the discussion is not here about social problems but about the natural world which describes and discusses processes completely independent of human activities.
If such a view seems so implausible that you wonder whether I am somehow exaggerating, consider the following assertions by prominent sociologists:
That is what they call: a whole different ball game.

For further reading

If you want to give a comment you can use the following form Comment form

Created: 23 December 2014

Back to my home page Index
Back to Nature comments Nature Index