Research on Gravitation, Relativity and Cosmology

普林斯顿实验计划的重点是测量热宇宙背景辐射（CBR）的角分布及其光谱和绝对温度。 这些是星系形成的场景的试验场;如果场景很简单，我们可能会发现编码在角分布中的关键宇宙学参数的值。 应更好地探索波长大于约3厘米的光谱，以改善对物质和辐射相互作用历史的限制。 这个小组从萨斯卡通进行的测量探测了CBR中不规则性的功率谱，其角度范围约为0.5到3。 他们将用地面望远镜改进这些探测，并建造一个气球载仪器，绘制各向异性图。 更好地测量CBR各向异性需要更灵敏和稳定的探测器和辐射计。 他们将建造和测试一个新的90 Ghz HEMT（高电子迁移率晶体管）辐射计，并开发一个小型宽带SIS接收器阵列， 90 GHz。 他们还将继续开发技术，以寻找光谱中的长波长失真。 这项研究的目的是通过理论和实验来增进对宇宙演化和大尺度结构的认识。 新的望远镜和探测器在广泛能量范围内灵敏度的改进已经产生了更大的数据，这些数据在标准宇宙学模型中面临着多种选择。 普林斯顿小组预计，在十年内，对数据的补充和对数据所允许的理论选择的仔细评估将产生对广义相对论的新检验，并且通过改进宇宙学模型的一致性检查，将严格限制星系形成及其大尺度分布的模型，也许告诉我们宇宙是开放的还是封闭的。 教育是这项研究的核心。 该小组非常重视本科教学;平均而言，该小组每年夏天监督六名本科生，并在学年期间监督十个独立的研究项目。 虽然许多人继续学习物理，但也有相当一部分人继续接受医学、工程或法律方面的教育。 教育研究生也具有高度优先地位。

The Princeton experimental program is centered on measurements of the angular distribution of the thermal cosmic background radiation (the CBR) and its spectrum and absolute temperature. These are a proving ground for scenarios of galaxy formation; if the scenario is simple we may find encoded in the angular distribution the values of key cosmological parameters. The spectrum at wavelengths greater than about 3 cm should be better explored to improve constraints on the history of interactions of matter and radiation. This group's measurements from Saskatoon detect the power spectrum of irregularities in the CBR on angular scales from about 0.5 to 3. They will improve these detections with their ground-based telescope and to build a balloon-borne instrument that produces a map of the anisotropy. Better measurements of the CBR anisotropy require more sensitive and stable detectors and radiometers. They will build and test a new 90 Ghz HEMT-based (High Electron Mobility Transistor) radiometer and to develop a small array of broad-band SIS receivers for 90 Ghz. They will also continue developing the techniques to search for long-wavelength distortions in the spectrum. The objective of this research is to advance knowledge, through both theory and experiment, of the evolution and large-scale structure of the universe. New telescopes and improvements in detector sensitivities over a broad range of energies have yielded a much enlarged fund of data that confront a multitude of options within the standard cosmological model. The Princeton group expects that within a decade additions to the data and a careful evaluation of the theoretical options the data allow will yield a new test of general relativity theory, and, through an improved check of consistency of the cosmological model, will sharply restrict models for the formation of galaxies and their large-scale distribution, and perhaps tell us whether the universe is open or closed. Education is central t o this research. The group places a strong emphasis on undergraduate teaching; on average, the group supervises six undergraduates each summer and ten independent research projects during the school year. Though many go on in physics, quite a few continue their education in medicine, engineering, or law. Educating graduate students also has high priority.