共查询到20条相似文献，搜索用时 750 毫秒
1.
《大科技．科学之谜》2006,(8)
【问题与解答】为什么光速不可超越?为什么光速是不变的?两束向相反方向传播的光线的相对速度难道不是2c而是c吗?——河南省扶沟县高级中学王少兵根据相对论,两物体的相对运动速度不仅和他们自己的运动速度有关,还和光速这个速度上限有关,即著名的洛伦兹相对速度变换公式v=(v1-v2)/(1-v1·v2/c2),设v1和v2是两物体相对第三者的速度,c是光速,v是物体间的相对运动速度;带入公式计算一下,你会发现当你无论以什么样的速度运动,都不会超过光速的!当你以光速运动时,你相对于谁都是光速,当然光相对于光也是光速了。爱因斯坦狭义相对论认为:光速不变… 相似文献
2.
3.
王亦军 《大科技．科学之谜》2010,(1):1-1
<正>都怪爱因斯坦!因为爱因斯坦提出,光速是速度的极限,没有任何物质的运动速度超过光速,也就是说,30万千米/秒的速度是宇宙中最快的速度,这就给我们观测宇宙带来很大的难题。 相似文献
4.
美国纽约州罗切斯特大学马修·毕格罗(MatthewBigelow)教授研究表明,在绝对零度的环境中通过装有红宝石晶体的研究装置,可以改变光的速度。能使光速减慢,也能使光速加速。但是,这项研究要求具备绝对零度的环境和复杂的装置才能实现。毕格罗教授的这项研究成果发表在《自然》杂志上。从理论上讲,光在真空中的传播速度为每秒30万公里,在玻璃介质中传播速度为每秒15万公里。然而,在所进行的实验中却能将光的速度减缓至每秒91米,也能加快光的速度,超过光在真空中的传播速度。在不违反自然定律的条件下,光速是不可超越的。但是,毕格罗教授通过研… 相似文献
5.
人阳辐射能来自太阳中心产能区的热核聚变反应。太阳中心区的热核反应，除了产生巨大数量的光子辐射，使太阳显得光辉夺目外，同时也产生看不见的以光速运动的中微子，直接逃逸出太阳。中微子是一种以光速运动的微粒子，它们与物质的相互作用机率非常小。中微子除了可与原子核发生作用外，也可以被电子散射，而被散射电子在介质中的运动将产生切伦 相似文献
6.
7.
《大科技．科学之谜》2006,(3)
[问题与解答]我们知道,如果给运动的物体一个力,它就会加速运动,可不可能一直给一个运动的物体一个力,让它加速直到光速甚至超越光速?——陕西省富平县迤山中学高中马航爱因斯坦的相对论认为,真空中光速为每秒30万公里,是宇宙中一切速度的上限,也就是说没有任何物体的速度能超过光速。因为根据爱因斯坦质量与速度公式,即便是质量极小的物体,随着速度的加快,其质量也会变大。当速度越来越接近光速时,加给物体的力就越来越多地转变为物体的质量,使物体的质量越来越大。因此,爱因斯坦认为,不可能使一个具有静止质量的物体加速到光速。有关相对… 相似文献
8.
真空中光速不变是被证明了的事实,但有观点认为在宇宙演化的不同时期,光速可能是有差别的。本文根据这个观点,自然推导出黑洞的质量上限,由此能够很好地解释类星体超强辐射的能源机制,并由光速量子化得到黑洞爆炸乃至宇宙大爆炸的条件。 相似文献
9.
10.
徐杰 《大科技．科学之谜》2010,(9):51-51
关于物质世界与反物质世界的存在,根据推断我认为：物质世界就是引力大于斥力的时空世界。因为引力场运动速度是亚光速的．所以物质世界的物体运动速度是不会超光速的．它表现为引力质量的世界。 相似文献
11.
中国科学院"江门中微子实验"战略性先导科技专项研究团队 《中国科学院院刊》2015,30(5):685-692
中微子物理是粒子物理最重要的前沿之一,存在众多未解之谜,可能成为超出标准模型的新物理突破口,也是粒子物理、天体物理和宇宙学研究的交叉前沿。大亚湾中微子实验2012年出人意料地发现大的新中微子振荡模式,使近期测量中微子质量顺序和CP相角成为可能。江门中微子实验(原名大亚湾二期实验)2013年得到中科院战略性先导科技专项支持,2015年启动建设,预计2020年投入运行。它以测量中微子质量顺序为核心科学目标,同时精确测量中微子6个振荡参数中的3个,达到好于1%的国际最好水平,使检验中微子混合矩阵的幺正性、发现新物理成为可能。它也可以研究超新星中微子、地球中微子、太阳中微子、大气中微子,寻找暗物质、质子衰变等,在多个领域达到国际先进水平,不仅能对理解微观的粒子物理规律做出重大贡献,也将对宇宙学、天体物理乃至地球物理做出重大贡献。 相似文献
12.
论入世对科技体制的影响与对策 总被引：2，自引：0，他引：2
本文分析了WTO中与科技创新政策有关的内容及其给科技体制改革提供的机会,并结合实际,提出充分利用入世机遇,加快科技体制改革的政策建议。 相似文献
13.
V.K. Zworykin 《Journal of The Franklin Institute》1933,215(5):535-555
For many experiments in physics and in some engineering applications, it is necessary to produce electron bundles, or as they are often called, “electron beams” of considerable intensities.Various methods have been used for directing a cloud of electrons evaporated from an emitting surface into a beam and then concentrating this beam to a desired degree. The concentration of electron beam in high vacuum depends entirely upon fields of force, either electric or magnetic, while in low vacuum or in rarified rare gas it depends also upon the action of the field of ionized gas molecules.In high vacuum the fields of force act upon the electron beam in a manner similar to the action of lenses upon a beam of light. An improperly shaped field produces effects similar to spherical aberration in poorly corrected lenses; non-uniform velocity of electrons in the beam results in effects similar to chromatic aberration of light.This optical analogy is not perfect.In the case of the electron beam the velocity varies continuously throughout most of the path and indices of refraction employed usually are greater than in the optical case. Moreover, space charge in beams of high intensity limits the concentration attainable; consequently, even theoretically, an electron beam can never be brought up to a mathematical point as in the case of light optics. Many secondary effects are present which complicate the problem still further.In focusing electron beams, both electrostatic and electromagnetic methods have been used extensively. The electrostatic method, however, seems to be preferable, especially when the beam is to be deflected. Precautions should be taken not to destroy the focusing of the beam during deflection. 相似文献
14.
Thomas K. Gaisser Author Vitae Stuart Pittel Author Vitae 《Journal of The Franklin Institute》2004,341(3):223-229
This award recognizes years of research by the laureates using elusive neutrinos to probe the internal workings of the sun. Bahcall and Davis identified an apparently fundamental problem: the fusion reactions that generate the sun's power deep in its core appeared to generate fewer neutrinos than expected. The number of neutrinos detected by Davis was only about a third the number calculated by Bahcall. Koshiba developed a new type of detector that not only confirmed the deficit but also showed that the neutrinos counted by Davis actually come from the Sun. Together the work of these three scientists prepared the way for the resolution of the puzzle, the discovery of a new property of neutrinos called “neutrino oscillations”. On the way from the sun, some neutrinos change identity and become nearly invisible in the detectors. This insight promises to open up new vistas in the fundamental physics of elementary particles. 相似文献
15.
V.K. Zworykin 《Journal of The Franklin Institute》1934,217(1):1-37
This paper gives an outline of a new television system developed in the laboratories of RCA Victor Company, in Camden, N. J.The system is truly electrical and employs only electronic devices, without a single mechanically moving part.The translation of the visual image is accomplished by means of a vacuum tube called the iconoscope. This tube is a virtual electric eye and consists of a photo-sensitive mosaic corresponding to the retina of the human eye, and a moving electron beam representing the nerve of the eye. The image is projected optically on the mosaic and transformed within the tube into a train of electrical impulses, representing the illumination of individual points of the image.The reproduction of the image is accomplished by means of another vacuum tube, the kinescope, which transforms the electrical impulses back into the variation of light intensity through the bombardment of a fluorescent screen by the moving electron beam.The movement of the electron beams in both tubes, which is responsible for both transformations, is linear and divides the picture into a series of parallel lines. The movements are synchronized so that the instantaneous position of the beams with respect to a point in the picture is always identical. The synchronization is transmitted together with the picture signals, and operation of the receiver is completely automatic.The sensitivity of the iconoscope, at the present time, is approximately equal to that of a photographic film operating at the speed of a motion picture camera, permitting the transmission of outdoor scenes. The resolution is high, much higher than necessary for television images of the highest quality.The paper describes the theory of the system, its characteristics, mode of operation, and includes photographs of images obtained on the fluorescent screen of the receiver. 相似文献
16.
Thomas K. Gaisser 《Journal of The Franklin Institute》2011,348(3):453-458
This award recognizes two specific discoveries that constitute the experimental discovery of neutrino oscillations. In 1998 the Super-Kamiokande group under the leadership of Yoji Totsuka published their paper, “Evidence for Oscillation of Atmospheric Neutrinos” in Physical Review Letters [1]. The paper describes a deficit of muon-type neutrinos from below the detector relative to those from above. It explains this “atmospheric neutrino anomaly” as a result of transformation of some of the muon neutrinos into another type of neutrino. Four years later, the group led by Arthur McDonald described “Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory” [2] in the same journal. This experiment detected lower energy neutrinos from deep inside the Sun. By measuring all flavors of neutrinos with large rates, the SNO collaboration showed definitively that the long-standing “solar neutrino puzzle” was another manifestation of neutrino oscillations. As a result of these two experiments, we now understand that neutrinos can change identities during propagation and that both the solar and atmospheric neutrino “problems” result from the same underlying phenomenon of oscillations. A consequence of neutrino oscillations is that neutrinos, previously thought to be massless, must have a non-zero rest mass. 相似文献
17.
我国高技术产业和制造业种群演化规律的生态研究 总被引：3，自引：0，他引：3
中国在一个制造业大国的基础上努力推动高技术产业的发展,所以高技术产业和传统制造业之间的联动演化关系对于制定良好的产业发展政策非常重要。本研究从我国高技术产业和传统制造业之间的联动演化关系出发,在两个产业演化发展规律的基础上通过传染病模型分析两种产业种群之间联动演化关系。研究发现我国的高技术产业和传统制造业之间相互促进的作用非常小,而且制造业企业数对高技术企业数的变化存在一定的限制作用,这种关系在一定程度上反映了中国产业结构的健康状况,并可为国家发展高技术产业提供一定程度的政策参考。 相似文献
18.
郭继海 《科学技术与辩证法》2010,27(4):25-29
朴素的概率衰减论是把逻辑和心理混同的产物,由心理活动中可能存在衰减而推断命题的真假有程度的不同,进而要求或者为了保全真的高程度而少推理,或者为了构造更复杂的理论而放弃真理概念。这种观点对逻辑推演、理论构造和科学发展都是障碍。就命题的真值以及推演的逻辑结构看,它们都是逻辑事件而不是随机事件,因而推理链条越长结论为真的概率越低之说就是语词误用。逻辑方面不存在概率衰减,只有心理方面才可能存在概率衰减。逻辑方面和心理方面尽管事实上不能分割开,但理论上必须有某种程度的区分。 相似文献
19.
中国黄土高原春季干旱10a际演变特征 总被引：1，自引：0，他引：1
根据黄土高原7省区48个具有代表性的气象台站1961-2010年的气候要素资料,利用基于相对湿润度的干旱等级指数,分析了近50a黄土高原春季干旱10a际时空分布和演变特征。结果表明:1961-2010年黄土高原春季干旱发生频率呈东南向西北递增分布特征,且春季轻旱发生频率最大。以西北部为主的干旱南边界以(40~60)km/10a的速度由西北向东南扩展,近50a南边界向东南扩展推进了200~300km;干旱面积以4%/10a的速度增加,近50a干旱面积扩大到占高原面积的94%。以中部为主的黄土高原大部分区域春季干旱强度呈增强趋势,中部腹地干旱强度增强幅度最大,中部周边干旱强度增强幅度次之;东北部和西部边缘干旱强度呈减弱趋势。干旱指数存在显著的3~4a高频振荡周期。1971年为干旱强度显著加强的突变点,预计未来数年黄土高原干旱仍处在面积扩大、强度增强过程中。 相似文献
20.
尽管与传统图书和电子书相比,增强现实(AR)图书有着更加优化的展示效果和开发潜力,但作为一种新兴事物,与国外相比,当前国内的AR图书研究较少,也缺乏相关的实证分析。运用结构方程(SEM)研究方法,对影响AR图书用户购买意愿的功能价值、认知价值、社会价值、情感价值、经济价值、条件价值和选择态度等因素进行量化分析,并以此为基础,提出跨平台宣传、多渠道融资、平衡性价比和立体化营销的对策建议。 相似文献