Power calculation for gravitational radiation: oversimplification and the importance of time scale

A simplified formula for gravitational-radiation power is examined. It is shown to give completely erroneous answers in three situations, making it useless even for rough estimates. It is emphasized that short timescales, as well as fast speeds, make classical approximations to relativistic calculations untenable.Comment: Three pages, no figures, accepted for publication in Astronomische Nachrichte

Problems in the Science and Mathematics of 'The Logic of Scientific Discovery'

Professor Sir Karl Popper (1902-1994) was one of the most influential philosophers of science of the twentieth century. However, in his most famous work 'The Logic of Scientific Discovery' he displays troubling misunderstandings of science and mathematics at a basic level. These call into question his conclusions concerning the philosophy of science.Quanta 2012; 1: 13–18

A New Galaxy in the Local Group: the Antlia Dwarf Galaxy

We report the discovery of new member of the Local Group in the constellation of Antlia. Optically the system appears to be a typical dwarf spheroidal galaxy of type dE3.5 with no apparent young blue stars or unusual features. A color-magnitude diagram in I, V-I shows the tip of the red giant branch, giving a distance modulus of 25.3 +/- 0.2 (1.15 Mpc +/- 0.1) and a metallicity of -1.6 +/- 0.3. Although Antlia is in a relatively isolated part of the Local Group it is only 1.2 degrees away on the sky from the Local Group dwarf NGC3109, and may be an associated system.Comment: AJ in press, 15 pages, 7 figures, figure 2 in b/w for space saving, full postscript version available at http://www.ast.cam.ac.uk/~gkth/antlia-pp.htm

Problems in the Science and Mathematics of 'The Logic of Scientific Discovery'

Professor Sir Karl Popper (1902-1994) was one of the most influential philosophers of science of the twentieth century. However, in his most famous work 'The Logic of Scientific Discovery' he displays troubling misunderstandings of science and mathematics at a basic level. These call into question his conclusions concerning the philosophy of science. Quanta 2012; 1: 13–18

You Can't Get There From Here: Hubble Relaxation in the Local Volume

A beginning end-point for galaxy motions within the 10-Mpc Local Volume is constructed by requiring a smooth distribution of (luminous) mass at the time of recombination, which is shown to be equivalent to a smooth Hubble flow at early times. It is found, by this purely kinematical method, that present peculiar motions are too small by a factor of at least several (and largely in the wrong direction) to have produced the observed structures within the age of the universe. Known dynamical effects are inadequate to remove the discrepancy. This result is different in origin from previously known ``cold flow'' problems. The simple dynamical picture often used within the Local Volume (for instance, in deriving masses through calculation of a zero-velocity surface) is thus called into question. The most straightforward explanation (though not the only possible) is that there exists a large quantity of baryonic matter in this region so far undetected, and unassociated with galaxies or groups.Comment: 23 pages, accepted by the Astronomical Journa