物理学未决问题浅说:宇宙中的反超星系团

'一阴一阳之谓道'。我国古代的阴阳学说曾使玻尔震惊,他认为古代东方智慧与现代西方科学之间有着深刻的协调性。自古以来,'阴'与'阳'这两个字,不但表示黑暗与光明,而且表示女性与男性、柔与刚、下与上、负与正,乃至万事万物中对立着的两面。有电子就有正电子,有质子就有反质子。

探索宇宙反物质的对话

甲:茫茫宇宙中很多未解之谜鼓舞着我们去不断探索。我们要讨论的宇宙反物质和暗物质,就是其中两个未解之谜。这里我们着重谈谈探索宇宙反物质和暗物质的科学意义,以及怎样用在空间站上的实验仪器去探索宇宙反物质和暗物质。乙:提起反物质:使我想起前些时候报导过这样的消息:欧洲核子研究中心的科学家,利用原子和反质子碰撞产生了反氢原子。尽管这种在实验室条件下产生的反氢原子的寿命很短,只有四百亿分之一秒,却引起了关心科学的公众极大的兴趣。这种反氢原子就是反物质吧?甲:是的。在介绍反物质之前,我们先要提到粒子和物质。这里所说的粒子,是微观粒子的简称。比如电子、中子、质子等等都是粒子。我们知道,物质是由微观粒子组成的。质子和中子组成原子核。带正电的原子核和带负电的电子组成原子。各种原子组成了宇宙中的各种物质。本世纪三十年代初,英国物理学家狄拉克提出反物质的假说。世界上所有的粒子都有它们相应的反粒子。例如,每一种夸克都有它的反夸克,每一种轻子都有它的反轻子。有电子就有反电子,也叫正电子。有质子就有反质子,有中子就有反中子。

反物质 : 奇怪的世界

反物质：奇怪的世界陈壮叔１９９６年，欧洲核子研究所（ＣＥＲＮ）制造出９颗反氢原子，成为轰动全球的科技大新闻，这使人联想到，我们宇宙是否存在反物质世界。反物质世界听起来很奇怪，其实不然，在亚原子粒子中，每个粒子皆有其反粒子为伴，两者的性质正好相反，如电...

Observed Relationship between Surface Freshwater Flux and Salinity in The North Indian Ocean

Using 10-year (2001 10) monthly evaporation, precipitation, and sea surface salinity (SSS) datasets, the relationship between local freshwater flux and SSS in the north Indian Ocean (NIO) is evaluated quantitatively. The results suggest a highly positive linear correlation between freshwater flux and SSS in the Arabian Sea (correlation coefficient, R=0.74) and the western equatorial Indian Ocean (R=0.73), whereas the linear relationships are relatively weaker in the Bay of Bengal (R=0.50) and the eastern equatorial Indian Ocean (R=0.40). Additionally, the interannual variations of freshwater flux and SSS and their mutual relationship are investigated in four sub- regions for pre-monsoon, monsoon, and post-monsoon seasons separately. The satellite retrievals of SSS from the Soil Moisture and Ocean Salinity (SMOS) and Aquarius missions can provide continuous and consistent SSS fields for a better understanding of its variability and the differences between the freshwater flux and SSS signals, which are commonly thought to be linearly related.

Verification of Net Primary Production Estimation Method in the Mongolian Plateau Using Landsat ETM+ Data

We plan to estimate global net primary production (NPP) of vegetation using the Advanced Earth Observing Satellite\|Ⅱ (ADEOS\|Ⅱ) Global Imager (GLI) multi\|spectral data. We derive an NPP estimation algorithm from ground measurement data on temperate plants in Japan. By the algorithm, we estimate NPP using a vegetation index based on pattern decomposition (VIPD) for the Mongolian Plateau. The VIPD is derived from Landsat ETM+ multi\|spectral data, and the resulting NPP estimation is compared with ground data measured in a semi\|arid area of Mongolia. The NPP estimation derived from satellite remote sensing data agrees with the ground measurement data within the error range of 15% when all above\|ground vegetation NPP is calculated for different vegetation classifications.

反物质的发现

反物质的发现靳峻竹张运斌（陕西师范大学，西安，７１００６２陕西榆林农校，７１９０００）１９９６年１月４日，欧洲核子研究中心宣布制造出９个反氢原子，从而在世界上第一次制造成了一种反物质．同年１１月１２日，美国费米实验室利用对撞机又制造出７个反氢原子，进...

Forest-height inversion using repeat-pass spaceborne polInSAR data

Forest-height inversion using airborne double-antenna synthetic aperture radar(SAR)systems has been widely researched,leading to increasing accuracy.Polarimetric SAR Interferometry(PolInSAR)data from spaceborne single-antenna SAR systems,which are influenced by temporal decorrelation,have difficulty inverting forest height.Given the temporal decorrelation effect,the classical random volume over ground(RVoG)model has been proven to invert forest height with significant errors,using repeat-pass PolInSAR data.In consideration of this problem,the temporal decorrelation RVoG(TD-RVoG;based on the RVoG)model was proposed.In this study,an improved TD-RVoG model is presented,with a new temporal decorrelation function.Compared with TD-RVoG,the new model has fewer unknown parameters and can be applied in a three-stage inversion procedure.Validity of the new model is demonstrated by Advanced Land Observing Satellite/Phased Array type L-band SAR(ALOS/PALSAR)data.Results show that the improved TD-RVoG has better accuracy,with inversion error less than 1.5m.

Global characteristics of the second-order ionospheric delay error using inversion of electron density profiles from COSMIC occultation data

It is a well known fact that ionospheric delay error is a predominant factor which influences the positioning accuarcy of GNSS.Although the main part of the first-order ionospheric delay error can be removed by the frequency-dependent behaviors of the ionosphere,the second-order ionospheric delay error must be eliminated to achieve millimetre-scale positioning accuracy.Due to COSMIC occultation providing electron density profiles on the global scale,the paper presents the first-order and the second-order ionospheric delay error analysis on the global scale using the inversion of electron density profiles from COSMIC occultation data during 2009–2011.Firstly,because of the special geographical location of three ISR(incoherent scatter radar),the first-order and the second-order ionospheric delay errors are calculated and discussed;the paper also shows and analyzes the diurnal,seasonal,semi-annual variation of ionospheric delay error with respect to signal direction.Results show that for the L1 signal path,the first-order ionospheric delay error is the largest near the equator,which is circa 7 m;the maximum second-order ionospheric delay error are circa 0.6 cm,0.8 cm and 0.6 cm respectively for L1 signals coming from the zenith,the north and the south at 10 degree elevation angles.The second-order ionospheric delay error on the L1 signal path from zenith are the symmetry between 15°and 15°with respect to magnetic equator,and are nearly zero at the magnetic equator.For the first time,the second-order ionospheric delay error on the global scale is presented,so this research will greatly contribute to analysing the higher-order ionospheric delay error characteristics on the global scale.