It's been more than 50 years since astronomers first proposed "dark matter," which is thought to be the most common form of matter in the universe. Even so, we have no idea what dark matter is. No one has seen dark matter directly or produced it in a lab. But are there competing theories that explain the same data better?
By Antonis Antonio, PhD student in Philosophy of Science, University of Bristol
עברו יותר מ-50 שנה מאז שאסטרונומים הציעו לראשונה את "החומר האפל", שנחשב לצורת החומר הנפוצה ביותר ביקום. למרות זאת, We have no idea what is dark matter No one has seen dark matter directly or produced it in a lab. But are there competing theories that explain the same data better?
So how can scientists be so sure it exists? It turns out that philosophy can help us answer these questions.
Back in the 70s, seminal research by astronomers Vera Rubin and Kent Ford about how our neighboring galaxy Andromeda rotates revealed A surprising inconsistency between theory and observation. According to our best gravitational theory - Newton's laws – Stars and gas in a galaxy should rotate more and more slowly the farther they are from the center of the galaxy. This is because most of the stars will be close to the center, which will create a strong gravitational force there.
Rubin and Ford's findings showed that this was not the case. Stars on the outer edge of the galaxy moved about as fast as the stars around its center. The idea that the galaxy must be embedded in a large halo of dark matter was originally proposed to explain this anomaly (although others have suggested this before). This invisible mass interacts with the outer stars through gravity to increase their speeds.
This is just one example of several anomalies in cosmological observations. However, most of them can equally well be explained by modifying the current gravitational laws of Newtonian dynamics and general relativity of Einstein. Maybe nature behaves a little differently on certain scales than these theories predict?
One of the first theories of this kind, developed by the Israeli physicist Mordechai Milgrom in 1983, suggested that Newton's laws may work slightly differently when very small accelerations are involved, such as at the edge of galaxies. This change perfectly matched the observed galactic rotation. Nevertheless, physicists today overwhelmingly favor the dark matter hypothesis incorporated in the so-called model ΛCDM (Lambda's cold dark matter).
השקפה זו מושרשת כל כך חזק בפיזיקה, עד שהיא מכונה "המודל הסטנדרטי של הקוסמולוגיה". עם זאת, אם שתי התיאוריות המתחרות של החומר האפל והכבידה המתוקנת יכולות להסביר באותה מידה את הסיבוב הגלקטי ואת החריגות האחרות, אפשר לתהות אם יש לנו סיבות טובות להעדיף אחת על פני השנייה.
הגרף מציג את מהירות הסיבוב של כוכבים וגז (ציר אנכי) כפונקציה של המרחק שלהם מהמרכז (ציר אופקי). התיאוריה מציעה שעלינו לקבל את הגרף המסומן 'צפוי על ידי הדיסק הנראה', אך המציאות שונה. ויקיפדיה, CC BY-SA
Why does the scientific community have a strong preference for the dark matter explanation over changes in gravity? And how can we ever decide which of the two explanations is correct?
Philosophy comes to the rescue
זוהי דוגמה למה שפילוסופים מכנים "Sub-definition of the scientific theory" על ידי הראיות הזמינות. זה מתאר כל מצב שבו הראיות הזמינות עשויות להיות לא מספיקות כדי לקבוע אילו אמונות עלינו להחזיק בתגובה לכך. זוהי בעיה שהדהימה את הפילוסופים של המדע במשך זמן רב.
In the case of the strange rotation in galaxies, the data alone cannot determine whether the observed velocities are due to the presence of additional unobserved matter or to the fact that our current laws of gravity are incorrect.
That's why scientists are looking for additional data in other contexts that will eventually clarify the answer to the question. One of the examples of this is in favor of dark matter comes from the observations About how matter is distributed in the Bullet galaxy cluster, which consists of two colliding galaxies about 3.8 billion light-years from Earth. The second is based on measurements of the way light is deflected by (invisible) matter in the cosmic microwave background radiation - the light left over from the big bang. These are often seen as indisputable evidence in favor of dark matter, because Milgrom's original theory cannot explain them.
However, following the publication of these results, additional theories of different gravity were developed during the last decades in order to explain all the observational evidence for dark matter, sometimes successfully Great. However, the dark matter hypothesis still remains the preferred explanation for physicists. Why?
One way to understand this is to use the philosophical tools of Bayesian confirmation theory. It is a probabilistic framework for assessing the extent to which hypotheses are supported by the available evidence in different contexts.
In the case of two competing hypotheses, what determines the final probability of each hypothesis is the product of the ratio between the initial probabilities of the two hypotheses (before the evidence) and the ratio between the probabilities that the evidence appears in each case (called the likelihood ratio).
If we accept the fact that the most sophisticated versions of modified gravity and dark matter theory are equally supported by the evidence, then the likelihood ratio is equal to one. This means that the final decision depends on the initial probabilities of these two hypotheses.
הקביעה מה בדיוק נחשב כ"הסתברות הראשונית" של השערה, והדרכים האפשריות שבהן ניתן לקבוע הסתברויות כאלה, נותרה אחד האתגרים הקשים ביותר בתורת האישור הבייסיאנית. וכאן מתברר שניתוח פילוסופי מועיל.
In the heart Philosophical literature In this issue lies the question of whether the initial probabilities of scientific hypotheses should be determined objectively based on probabilistic laws and rational constraints only. Alternatively, they can include a number of other factors, such as psychological considerations (whether scientists favor a particular hypothesis based on interest or for sociological or political reasons), background knowledge, the success of a scientific theory in other fields, and so on.
Identifying these factors will ultimately help us understand the reasons why the dark matter theory is overwhelmingly favored by the physics community.
Philosophy cannot ultimately tell us whether astronomers are right or wrong about the existence of dark matter. But he can tell us whether astronomers do have good reasons to believe in it, what those reasons are, and what it will take for modified gravity to become as popular as dark matter.
We don't know the exact answers to these questions yet, but we're working on it. More research in the philosophy of science will help us reach a conclusion.
Comments
In response number 10 from a few days ago, I showed a method for explaining the reason for the rotation of the spiral galaxies, I expected the science responders to help me, but, the science responders were apparently tired and did not cooperate. But, nevertheless, I will give the solution:-
The solution I came to is not gravitation (!) but the pressure difference that exists throughout the universe, therefore, there is no need for dark matter and this also explains the accelerated expansion of the universe without dark energy!. Everything is explained in articles 75-85, a simple universe.
And good luck to Yair Lapid who started his job today:-
Our new Prime Minister for the next four months.
Please respond gently
Sabdarmish Yehuda
Please don't treat Asbar, he is mentally ill who escaped from the institution without permission.
I have a suggestion for the science responders!
בואו ביחד נעשה תרגיל "בחוכמת ההמונים", וננסה למצוא את הפתרון ההגיוני הנכון של הבעייה הקוסמולוגית הנ"ל,המוסברת בעזרת גרביטציה וחומר אפל.. אני אתחיל, ואתם תשלימו.
The idea is simple:-
In the first step - define the problem,
In the second step - we will find all the more or less successful options for a solution, - I found about 20 solutions,
In the third stage - we will sift through all the unsuccessful options, - I sifted through about 20 solutions.
In the fourth step - we will decide which solution is preferable from the rest. - I was left with 2 solutions.
ברור לכם שאם נעשה את ארבעת השלבים הנ"ל בצורה מושלמת אנחנו חייבים להגיע לפתרון מוצלח!
Here I need the responders of science, - as the wisdom of the masses.
Let's start-
Below is the first step: - defining the problem:
The gravitation formula of star m in the spiral galaxy M is given: F=M*m*G/r^2
This gravitation causes the rotational movement of star m in the galaxy: F=(mv^2)/r
These two formulas should be equal, but they are not. What could be the reasons for this?
We will move to the second stage and collect all the possible solutions for the solution, at this stage, without paying attention to their correctness. Here are the options:-
A. At least one of the members of the two formulas M m G rv must be different in size, for example M .
B. Correcting at least one of the formulas, for example correcting the rotational formula (MOND theory)
third. Replacing the formulas with other formulas, for example - electricity, magnetism, mechanical force, the strong force, the weak force, the Casimir effect
d. An external influence, such as the centrifugal force of the entire universe, another dimension, a parallel/twin universe, a living being, a higher power.
So far all the possibilities I have found, and before we move to phase C, the sifting phase, I expect the scientific readers to make their comments, and perhaps, to upgrade and find more options for a solution?.
Please respond gently
Sabdarmish Yehuda
I have a much better solution to the dark matter puzzle. Our universe is just one of many. Our universe is arranged in space according to the shape of a diamond, which we would expect to find, so that each of its twenty faces
Bordering another universe. The dark force is the gravitational force of the universes surrounding us. A ratio of one to twenty is key. Our universe is one, all observable matter, all atoms and particles make up five percent. The twenty are the universes around our universe, of course they are much, much more, but in the structural arrangement in the space of the honeycomb structure that Eshrimon allows for "holding" and prevents collapse.
כאשר את "מדען" הדוגל בתיאוריה שאינך יודע להסבירה – אות הוא שהינך קרוב מאד למוות של התיאוריה.
"מדענים" – המשיכו להתקשקש והניחו לעולם במנוחה.
Unveiled seminal research by astronomers Vera Rubin and Kent Ford about how our neighboring galaxy Andromeda rotates revealed a surprising inconsistency between theory and observation.
A completely crooked sentence in terms of structure, phrasing and logic
Nothing was said. The writer articulates our basic probability intuition in high terms, concludes that it is actually impossible to know what the probability is for each of the hypotheses, points out that if there are political or sociological biases this can have an effect (but does not say anything about what kind of biases can be expressed in relation to the aforementioned investments), And he concludes that the philosophy of science can perhaps help, but does not explain how.
The article states that more than 50 years have passed since astronomers proposed the concept of dark matter. This is technically true, but it is more accurate to write that it has been 100 years since astronomers first proposed the concept of dark matter:
https://ui.adsabs.harvard.edu/abs/1922ApJ….55..302K/abstract
כשקראתי "על פי התיאוריה הכבידתית הטובה ביותר שלנו – חוקי ניוטון –" – הפסקתי לקרא את הכתבה
Please attach to my previous message
Thanks
A. Asbar
http://img2.timg.co.il/forums/3/c8659042-cdd9-4060-b7fd-a3872d542a4b.pdf
Investigating reality by way of physical geometric imagination.
The simple and visible geometry teaches us how to approach the mysterious physics that is not visible to man.
First, the fundamental concept of geometry must be recognized, and this is an easy recognition.
The line is the fundamental concept of geometry, and has a millimeter length and shape.
(there is a straight line, there are infinite shapes of a closed circular line, and there are infinite shapes of a curved line),
Now we must look for the fundamental concept of physics, similar to the fundamental concept of geometry, and we will inevitably arrive at energy as some size, with many forms.
The size that must be is not yet clear, but the shapes are completely clear.
There is energy of heat, and of cold, and muscle energy, and energy of springs, and energy of height, and electrical energy, and chemical energy, and on and on
Physical geometric similitude guides the neural view in the study of reality.
A selected line has a quantitative size in millimeters, and is one of many shapes.
Energy has a quantitative size (not yet clear) and many forms.
This method of physical geometric similitude immediately yields a law that exists in reality.
The forms of energy alternate with each other, and the amount exchanged is always preserved.
Now it is already clear that there is a similarity between geometry and physics, but physics is much more complex, because it has a law of nature "the law of conservation of the quantity of energy forms"
Indeed, physics is much more complex than geometry, because apart from energy, there is another quantitative thing in it and that is the passive time.
Passive time is a measured quantitative thing, and has the characteristics of absolute rest and absolute cold.
Passive time fills the infinite space, it does not interfere with the movements of the stars, and is the necessary medium for the transmission of sunlight, in the style of "passive time waves".
Passive time does not exist in the Newtonian universe, nor does it exist in Einstein's universe.
With these two great researchers, only active time exists, which exists only in human consciousness. The clear concept of active time is "listening" to the heartbeat.
Between every two heartbeats we occupy an amount of active time, which fades and disappears immediately.
Compared to the active time that disappears from reality as soon as it is noticed, the passive time exists and is always there, and is the medium in which light waves move.
The passive tense has a very important role in the neural view, because matter is seen as a physical form, resulting from the addition of quantities of "two other quantitative things" and they are
Passive energy and time.
This is how the shape of the square is perceived by adding quantities of "two other quantitative things" and they are
The length of a closed line made up of 4 straight line segments of equal length, and within it an amount of space.
This is not the end of the wonders of neurophysics.
Just as there is passive time, there is also passive energy that does not change.
Every real body is made up of sums of passive time and energy, and when such a body is placed on an open spring resting on the surface of the earth, the spring will contract a little.
A compressed spring exhibits an amount of energy, and it comes from the body resting on the spring.
The law of conservation of energy also applies to passive energy.
Neurophysics presents a new reality, without quantum matter with gravity, and of course without dark matter, without electromagnetic waves but with waves of passive time,
There is no gravity, and no particles, but there are 5 continuous quantitative things in the world.
Length, area, volume, time and energy.
And the rest will be told in the article "A wonderful universe built from energy and passive time"
A. Asbar
In terms of the initial probabilities at the rational level, the question may actually be what is more likely:
1. השערה בדבר קונספט חדש של "חומר", שאין לנו מושג עד כה מהותי עליו פרט ל"דרישה" (- שהיא מין הנחה המניחה את המבוקש -) שהוא מפעיל ונפעל רק באופן גרביטציוני (זה המצב בהשערת החומר האפל); או,
2. A correction is required in the rules of the theory, such as a certain change in Newton's laws when a very small acceleration is involved (in Milgrom's theory).
נראה שהחלופה הראשונה משמעותה שינוי פראדיגמטי- קונספטואלי מופלג. זו השערה, עדיין לא תאוריה מדעית, והעדפתה טעונה הצגה של ראיות חד משמעיות, תאורטיות ואמפיריות, ובמקביל – שתציג הטלת ספק בכל הסבר אלטרנטיבי. ראיות מספיקות הן במקרה זה ענין בעייתי, שכן ללא בניה של תשתית קונספטואלית התשתית התאורטית נתונה בספק, וגם הניבוי ברמה הכמותית עלול להיות "הזמנה" מוטה מראש של תוצאות, או מין ניחוש.
It seems that the second alternative means only a local theoretical change. It is enough for her to explain the relevant phenomena to a theoretically satisfactory degree and to predict the results quantitatively at an acceptable level.
יחס ההסתברויות הסופיות בין החלופות אינו ברור, לעת עתה. נראה שהבולטות היחסית של תאוריית החומר האפל היא פונקציה של גורמים פסיכולוגיים, חברתיים ותרבותיים אופנתיים כלליים. מסתבר שהעולם מדעי מושפע מהעולם החברתי התרבותי הכללי, שבהם עדיין מאמינים ב"פרוגרס" סטיכי, ומצד שני רודפים אחר ריגושים אופנתיים. מבחינות אלה, המהפכנות הקונספטואלית של החומר האפל היא ללא ספק אארקטיבית יותר מהשמרנות היחסית של כל תאוריה מתחרה.
בסופו של דבר, ההתנסחויות בדבר בבסתברויות הראשוניות הן אולי צורות מורכבות של ניסוח עיקרון "התער של אוקהאם". עם זאת, העיקרון הזה וגם כללי ההסתברויות הראשוניות והסופיות אינם בגדר חוק, אלא העדפות של שכל פילוסופי ישר, ולכן ההכרה בשאלת ההסתברות הראשונה תושפע ישירות מהמאמץ המחקרי.
בפן המחקרי האמפירי, תשומת הלב צריכה להתמקד לא רק בנסיונות "להוכיח" קיומו של חומר אפל, יהיה מה שיהיה (ונסיונות כאלה כשלו עד כה כשלון מוחלט), אלא גם במדידה מדויקת של התאוצות בשולי גלקסיות מסוימות, בהן מתגלות אנומליות, ובניסיון לגלות גורמים משפיעים רלוונטיים (ענני גז, עצמים בעלי כוח משיכה חריג בצפיפות גבוהה, כגון חורים שחורים או כוכבי ניוטרונים, וכו') – אלא גם באותן גלקסיות שבהן התאוצות הנמדדות אינן חריגות מול התאוריה המקובלת. דיוק ועידון הממצאים האמפיריים עשוי מאוד לקדם את התחום.
In the theoretical field, studies that offer modifications to the accepted theories should certainly be encouraged.
מכל מקום, מה שלא נכון לעשות הוא להניח את נוכונותה של השערת החומר האפל כאילו היא "תאוריה" מדעית של ממש, בשעה שהיא לוקה בגרעון תאורטי ברור.