Saturday, December 31, 2011

Lists of Films on Atomic Bombs

The other day, I revived one of lost blog posts written in 2005. It was entitled "New books on atomic bombs." An overseas friend of mine wrote a comment on it and asked me if I knew a similar list of movies or documentaries. I did not know such a list. So, I made a search on the Internet, and results gotten are summarized here.

Lists of films on atomic bombs available on the Web
  1. Films about the atomic bombings of Hiroshima and Nagasaki (19 entires)
  2. Documentary films about the atomic bombings of Hiroshima and Nagasaki (subcategory of the above category) (9 entries)
  3. List of Japanese films on atomic bombs on the page "原爆映画特集" (Feature: Atomic Bomb Movies) (19 entries)
The third list above is difficult for the overseas friend to understand. Thus, I made a modified list as given below by including a few entries from the first two lists, adding English titles and providing links to English Wikipedia pages when available.

I wish that these films that convey the colossal tragedy the atomic bombs brought are appreciated by a lot more of people world over and that total elimination of nuclear weapons is realized as soon as possible.

List of Japanese films on atomic bombs (a modification of the list at "原爆映画特集")
Note: English titles are official ones except for those given in parentheses, which are used to indicate to be the literal translation by T.T. Some of Wikipedia pages explain not only about the film but also dramas, books, etc. of the same title; and some others contain an extremely brief description only.
Year of release Japanese title English title
1 1950 長崎の鐘 The Bells of Nagasaki
2 1952 原爆の子 Children of Hiroshima
3 1953 ひろしま (Hiroshima)
4 1955 生きものの記録 I Live In Fear
5 1959 第五福竜丸 (Lucky Dragon 5)
6 1963 (Mother)
7 1970 地の群れ Apart from Life
8 1976 はだしのゲン Barefoot Gen
9 1977 はだしのゲン: 涙の爆発 Barefoot Gen: Explosion of Tears
10 1980 ヒロシマのたたかい: はだしのゲンPART3 Barefoot Gen: PART3 Battle of Hiroshima
11 1983 この子を残して Children of Nagasaki
12 1983 せんせい (Sensei)
13 1988 さくら隊散る (Team Sakura Wiped Out)
14 1988 TOMORROW 明日 Tomorrow
15 1989 黒い雨 Black Rain
16 1991 八月の狂詩曲 Rhapsody in August
17 2001 H Story H Story
18 2002 鏡の女たち Women in the Mirror
19 2004 父と暮せば The Face of Jizo
20 2005 二重被爆 (Double exposure)
21 2007 夕凪の街 桜の国 Town of Evening Calm, Country of Cherry Blossoms
22 2007 馬頭琴夜想曲 Matouqin Nocturne
23 2009 妻の貌 (Wife's Face)

Friday, December 30, 2011

Boy of Age 16 Asks Me about Relativity, etc.
5. Object's Mass at Speed of Light

Abstract image reminiscent of light rays flying past.
Image: jscreationzs / FreeDigitalPhotos.net.
A friend of mine on Twitter, Aaron (a pseudonym), is an overseas, 16-year old boy, who seriously admires Albert Einstein and wants to become a physicist. He continually writes me (Ted, also a pseudonym) questions about the theory of relativity and related topics, and I am sending answers. In this series of blog posts, those questions and answers are reproduced with modifications. I am not an expert in the fields of physics related to relativity. So, my answers might contain errors. If you find any error, please do not hesitate to write a comment for the benefit, not only of the boy and me, but also of other readers.

Aaron: The object's mass is zero when it is traveling at the speed of light, right? Where does its mass go? Does it turn into energy?

Ted: Surely, what is traveling with the speed of light, i.e., the photon (the quantum of light and all other forms of electromagnetic radiation), has zero mass. It is to be noted that the photon always has zero mass and always flies with the seed of light. This property is known to belong to the photon only.*

Particles with masses different from zero, when they are at rest (rest masses), can be accelerated to speeds fairly close to the speed of light by the use of large accelerators such as the Large Hadron Collider in CERN. When the particle get higher speeds, the mass of the particle does not approach zero, contrary to your supposition, but becomes larger to make the total energy higher. As a result, no body with a nonzero rest mass can be accelerated to reach just the speed of light. This is explained below by the use of a few equations (clicking on the image, you can see a larger one). Thus, the situation in your question that an object with a finite rest mass would reach the speed of light does not happen.

* Neutrinos were once thought to have zero mass, but the experimentally established phenomenon of neutrino oscillation requires neutrinos to have nonzero masses. As for the experiment that suggested the possibility of neutrinos traveling faster than light, mention will be made in a later story of this series.
(Originally written on February 28, 2011)

Thursday, December 29, 2011

Boy of Age 16 Asks Me about Relativity, etc.
4. Newton vs Einstein

Isaac Newton. By Sir Godfrey Kneller [Public domain],
via Wikimedia Commons.
A friend of mine on Twitter, Aaron (a pseudonym), is an overseas, 16-year old boy, who seriously admires Albert Einstein and wants to become a physicist. He continually writes me (Ted, also a pseudonym) questions about the theory of relativity and related topics, and I am sending answers. In this series of blog posts, those questions and answers are reproduced with modifications. I am not an expert in the fields of physics related to relativity. So, my answers might contain errors. If you find any error, please do not hesitate to write a comment for the benefit, not only of the boy and me, but also of other readers.

Aaron: It seems that Newton did not know exactly how gravity worked. Then, there came Einstein to find the answer. Why do they still write about Newton's law of gravity in textbooks?

Ted: Newton's law of gravity and equation of motion are highly accurate approximations to Einstein's general and special theories of relativity. Einsteinian mechanics did not make Newtonian mechanics useless but expanded the scope of the latter. The latter is quite simple and yet is useful for doing calculations of the motion of materials being situated in a weak gravitational field and having a speed much smaller than the speed of light. Therefore, we first study Newtonian mechanics at high schools.

Note Added later: An educational blog post on the relation between Einstein's relativity and Newton's mechanics has appeared: Matt Strassler, "How did Einstein do it?" Blog site Of Particular Significance (2012).

(Originally written on February 24, 2011)

Monday, December 26, 2011

Boy of Age 16 Asks Me about Relativity, etc.
3. Space and Time

Diagram showing space and time in space-time. Here space is depicted as a two-dimensional entity in three-dimensional spacetime. Time from the observer's viewpoint is represented as a vertical line. Image by K. Aainsqatsi (Own work) [Public domain], via Wikimedia Commons.
A friend of mine on Twitter, Aaron (a pseudonym), is an overseas, 16-year old boy, who seriously admires Albert Einstein and wants to become a physicist. He continually writes me (Ted, also a pseudonym) questions about the theory of relativity and related topics, and I am sending answers. In this series of blog posts, those questions and answers are reproduced with modifications. I am not an expert in the fields of physics related to relativity. So, my answers might contain errors. If you find any error, please do not hesitate to write a comment for the benefit, not only of the boy and me, but also of other readers.

Aaron: Will there be time, if there is no space?

Ted: Your question does not seem to be a valid one in physics. Physics is the branch of natural science to study matter and its motion through spacetime; and these, i.e., matter, motion and spacetime, are inseparable from space.* From this viewpoint, physicists are not expected to think about the circumstance in which there is no space. In treating a complex problem, physicists often assume a simplified model of the situation, but elimination of space would make the problem non-physical.

However, the following should be noted in relation to your question: Approaches to quantum gravity, being studied for uniting quantum mechanics with general relativity, suggest the possibility that space and time are not fundamental entities but emergent phenomena (see, for example, Ref. 1). If such is the case, the phrase in your question, "there is no space," would have physical meaning in the sense that equations of quantum gravity would dispense with space and time variables.

* Especially in the theory of relativity, space and time (to say precisely, imaginary time) are treated symmetrically, and it can happen that part of time duration of one observer is part of spatial length of the other observer.

Reference
  1. Luboš Motl, Emergent space and emergent time, The Reference Frame (2004).
(Originally written on February 23, 2011)

Sunday, December 25, 2011

Boy of Age 16 Asks Me about Relativity, etc.
2. Einstein and Black Holes

Albert Einstein during a lecture in Vienna in 1921.
By Ferdinand Schmutzer [Public domain],
via Wikimedia Commons.

A friend of mine on Twitter, Aaron (a pseudonym), is an overseas, 16-year old boy, who seriously admires Albert Einstein and wants to become a physicist. He continually writes me (Ted, also a pseudonym) questions about the theory of relativity and related topics, and I am sending answers. In this series of blog posts, those questions and answers are reproduced with modifications. I am not an expert in the fields of physics related to relativity. So, my answers might contain errors. If you find any error, please do not hesitate to write a comment for the benefit of the boy and me as well as that of other readers.

Aaron: I read in some books that Einstein did not believe in black holes. Then, why did he publish the work of general relativity that predicted black holes?

Ted: When he developed the theory, Albert Einstein did not notice that it would predict the existence of black holes. Only after the publication of the paper on general relativity, other physicists studied solutions of Einstein field equations to find the possible existence of black holes. (For the detailed history of finding black hole solutions, see Ref. 1.)

Einstein's disbelief in the black hole solution is explained in Ref. 2 as follows:
It seems that Einstein always was of the opinion that singularities in classical field theory are intolerable. They are intolerable from the point of view of classical field theory because a singular region represents a breakdown of the postulated laws of nature. I think one can turn this argument around and say that a theory that involves singularities and involves them unavoidably, moreover, carries within itself the seeds of its own destruction.
In other words, Einstein's belief in his own theory combined with his opinion about physical theories in general did not allow the existence of the black hole. However, his theory was cleverer than his opinion and predicted what was confirmed by (indirect) observations. A physical theory or an equation can sometimes be more reliable than the philosophical opinion even of the greatest man.

References
  1. "Section 1. History" in "Black hole", Wikipedia, The Free Encyclopedia (19 December 2011 at 11:28).
  2. Quoted in Philosophical Problems of the Internal and External Worlds: Essays on the Phylosophy of Adolf Grünbaum edited by John Earman (University of Pittsburgh Press, 1993), as written by Peter Bergmann (1980, 156).

(Originally written on February 21, 2011)

Tuesday, December 20, 2011

Boy of Age 16 Asks Me about Relativity, etc.
1. Evidence for Black Holes


Illustration of black hole as a highly warped region of two-dimensional "space."
The real black hole is a highly warped region of four-dimensional spacetime.
Image: chrisroll / FreeDigitalPhotos.net

A friend of mine on Twitter, Aaron (a pseudonym), is an overseas, 16-year old boy, who seriously admires Albert Einstein and wants to become a physicist. He continually writes me (Ted, also a pseudonym) questions about the theory of relativity and related topics, and I am sending answers. In this series of blog posts, those questions and answers are reproduced with modifications. I am not an expert in the fields of physics related to relativity. So, my answers might contain errors. If you find any error, please do not hesitate to write a comment for the benefit of the boy and me as well as that of other readers.

Aaron: It is said that there are many black holes in our galaxy, right? Nobody can see them. Then, how do they know that there are black holes? I guess there is no equation to show that there is a black hole out there.

Ted: You are right. Neither there is an equation to predict the positions of black holes,* nor we can directly observe them. However, astronomers say that the center of our Milky Way Galaxy is dominated by one supermassive black hole and that observations have hinted at the existence of many stellar mass black holes (stellar black holes) near the galactic center (Ref. 1).

The evidence for the existence of black holes is obtained by indirect observations. Because of its invisible interior, the presence of them can be inferred through their interaction with other matter. For example, there is a phenomenon called accretion of matter. In this phenomenon, gas falling into a black hole emits vast amounts of radiation (mainly X-rays), which may be detected by telescopes. Astronomers have also identified numerous stellar black hole candidates in binary star systems, by studying their interaction with their companion stars. For more details about observation of black holes, you can see Refs. 2 and 3.

* As for the possible existence of black holes, Einstein's equations of general relativity helped later theorists to find such possibilities. However, those equations were solved under different simplifying assumptions by different theorists. So, the solutions thus obtained did not necessarily give a firm proof of the existence of the black hole.

References
  1. R. R. Britt, "Milky Way's center packed with black holes." Space.com (2005).
  2. "Section 4. Observational Evidence" in "Black hole", Wikipedia, the free encyclopedia (12 December 2011 at 05:45).
  3. T. Bunn, "Is there any evidence that black holes exist?" in Black Holes FAQ (Frequently Asked Questions) List (1995).

(Originally written on February 20, 2011; modified on December 23, 2011)