Cosmology and convention

I argue that some important elements of the current cosmological model are 'conventionalist’ in the sense defined by Karl Popper. These elements include dark matter and dark energy; both are auxiliary hypotheses that were invoked in response to observations that falsified the standard model as it existed at the time. The use of conventionalist stratagems in response to unexpected observations implies that the field of cosmology is in a state of 'degenerating problemshift’ in the language of Imre Lakatos. I show that the 'concordance’ argument, often put forward by cosmologists in support of the current paradigm, is weaker than the convergence arguments that were made in the past in support of the atomic theory of matter or the quantization of energy.     

Testing galaxy formation and dark matter with low surface brightness galaxies

Galaxies are the basic structural element of the universe; galaxy formation theory seeks to explain how these structures came to be. I trace some of the foundational ideas in galaxy formation, with emphasis on the need for non-baryonic cold dark matter. Many elements of early theory did not survive contact with observations of low surface brightness galaxies, leading to the need for auxiliary hypotheses like feedback. The failure points often trace to the surprising predictive successes of an alternative to dark matter, the Modified Newtonian Dynamics (MOND). While dark matter models are flexible in accommodating observations, they do not provide the predictive capacity of MOND. If the universe is made of cold dark matter, why does MOND get any predictions right?     

Experimentation in the cosmic laboratory

It might seem impossible to apply Ian Hacking's experimental argument for scientific realism to astrophysical objects; indeed Hacking himself expressed scepticism about extragalactic entities. Such astrophysical antirealism has been the subject of intense debate and is usually seen as an undesired consequence of experimental realism. In this paper, I claim that it is possible to recast the experimental argument by reference to James Woodward's non-anthropocentric account of experimentation so as to apply it to astrophysical entities, such as gravitational lenses. I also argue that this new formulation of the experimental argument solves several problems with Hacking's original version.     

恒星测光与天体物理的开端

现代意义上的恒星测光是伴随着宇宙观的转变而产生的。古代天球模型的打破,使人们意识到不同恒星离地球距离并不相同,从而建立起亮度-距离的简单模型。赫歇尔父子对恒星测光做出了开创性的贡献,约翰·赫歇尔制成第一台专门用于天文测光的天文光度计,并通过测光和数据统计认识到恒星亮度不仅与距离有关,而且与恒星内在性质有关。在19世纪前期,天文测光面临"标准烛光"的选取和控制不同观测者对颜色亮度的感知误差两大问题。德国物理学家泽尔纳结合光学与视觉心理学重新设计了天文光度计,一举解决了这两个问题。更为重要的是,经由精确测光,泽尔纳把恒星颜色与亮度联系起来,提出了一套恒星演化理论,成为早期天体物理学理论的代表。     

近代天体物理学中的毕达哥拉斯主义倾向

在科学哲学中,毕达哥拉斯主义的要旨是认为物理世界的奥秘在于数学和谐或基本对称性。本文通过近代天体物理学发展史的考察表明,这一思想不仅对行星运动定律的发现有决定性意义,而且对宇宙模型的建构和近代天体力学体系的建立都有启示价值。