paradox Physics

15 个科学问题 · 物理 Physics

本页目录

量子擦除实验如何“恢复”已经消失的干涉?

How does a quantum eraser 'restore' interference that already vanished?

若记录哪条缝的信息后来被“擦除”(使路径变得不可区分),干涉条纹会重新出现,哪怕决定在光子通过后才做出;说明可获取的路径信息、而非物理扰动,才是干涉消失的关键。
If which-path information is later erased (made indistinguishable), fringes reappear even after the photon passed; it shows accessible path information, not physical disturbance, kills interference.
难度 专业 · 适合 高中(15-18) CC BY 4.0 · 来源待核验 · Source pending review
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出处备注:著录含书名,但缺版次 / 出版社 / 年份中的一部分,需编辑补全后才能做独立比对。

Scully 与 Druhl,《量子擦除》,Nature 351 (1991)

Scully & Druhl, 'Quantum Eraser', Nature 351 (1991)

#量子擦除 #路径信息 #干涉

薇格纳朋友与“客观实在”之争焦点在哪?

Where does the Wigner's friend debate about objective reality focus?

若朋友在密闭实验室里测了量子系统,门外薇格纳用“整个实验室”做叠加描述——两人对“是否发生确定结果”看法冲突,逼问测量与意识、相对论参考系的边界。
If a friend measures a system inside a lab, Wigner outside can describe the whole lab as a superposition—they disagree on whether a definite outcome occurred, probing the boundary of measurement, objectivity and reference frames.
难度 专业 · 适合 高中(15-18) CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source

出处备注:著录含书名,但缺版次 / 出版社 / 年份中的一部分,需编辑补全后才能做独立比对。

Wigner,《对心-身问题的评论》,载于《The Scientist Speculates》(1961)

Wigner, 'Remarks on the Mind-Body Question', in 'The Scientist Speculates' (1961)

#薇格纳朋友 #客观实在 #测量

为什么麦克斯韦方程组在伽利略变换下不协变,却长期被认为正确?

Why were Maxwell's equations long accepted though not Galilean covariant?

19世纪以以太为绝对静止参考系,方程在该系成立;只有当爱因斯坦用洛伦兹变换与光速不变重建时空,才揭示电磁与力学的统一框架,旧协变问题随之消解。
In the 19th century the aether was the absolute frame where the equations held; Einstein's Lorentz transformation and light-speed invariance unified EM with mechanics, dissolving the covariance issue.
难度 专业 · 适合 高中(15-18) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
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Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #麦克斯韦 #相对论

为什么在密闭车厢里向上跳起还会落回原地,而不是被甩在后面?

Why, jumping up in a moving closed train, do you land in the same spot rather than being left behind?

你和车厢共享相同水平速度,跳起后水平惯性让你保持该速度(无水平外力);伽利略相对性说明匀速参考系内竖直运动与静止时无异,所以落回原地。
You share the train's horizontal velocity; with no horizontal force you keep it while airborne. Galilean relativity says vertical motion in a uniform frame is the same as at rest, so you land in place.
难度 专业 · 适合 高中(15-18) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
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Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #伽利略相对 #惯性

为什么可逆卡诺热机效率最高却不现实?

Why is the reversible Carnot engine the most efficient yet impractical?

卡诺效率 1-Tc/Th 是可逆极限,要求所有传热在无穷小温差下进行,意味着功率趋零、循环无限慢;实际引擎用有限温差换功率,效率低于卡诺。
Carnot efficiency 1−Tc/Th is the reversible limit needing infinitesimal temperature gaps, so power tends to zero and cycles infinitely slow; real engines trade efficiency for finite power.
难度 专业 · 适合 高中(15-18) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
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Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #卡诺 #效率

为什么在加速电梯里分不清是重力还是加速度(等效原理的日常版)?

Why can't you tell gravity from acceleration inside an accelerating elevator?

在密闭电梯里,向下加速 a 会减少你对地板的压力,与重力减弱等效;向上加速则增重,与重力增强等效;局域上两者产生的力学效应完全相同,这就是等效原理。
In a closed elevator, downward acceleration reduces your apparent weight like weaker gravity; upward acceleration adds weight like stronger gravity. Locally the effects are identical—the equivalence principle.
难度 进阶 · 适合 高中(15-18) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source

Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #等效 #加速度

麦克斯韦妖如果真的存在,会推翻热力学第二定律吗?

If Maxwell's demon really existed, would it overturn the second law?

不会。妖要“看”并记住分子信息,擦除记忆必然产生至少同等热量(朗道尔极限),整体熵不减,第二定律依然成立。
No. The demon must observe and remember; erasing that memory costs at least as much heat (Landauer limit), so total entropy still rises and the second law holds.
难度 进阶 · 适合 初中(12-15) CC BY 4.0 · 已核验 · Verified 2026-11-03
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Maxwell,《热的理论》(1871)

Maxwell, 'Theory of Heat' (1871)

#麦克斯韦妖 #熵 #朗道尔

为什么把冰和温水放进保温杯摇晃,水温不会降到0℃以下?

Why doesn't shaking ice and warm water in a thermos drop below 0°C?

冰融化吸热把水冷却,但只要有冰存在平衡温度就是0℃;摇晃只加速热交换不会创造更低温度,除非额外做功或相变,否则不会低于冰点。
Melting ice cools the water, but with ice present the equilibrium is 0°C; shaking only speeds exchange, it can't make it colder without extra work or phase change.
难度 进阶 · 适合 初中(12-15) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source

Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #平衡 #熔化

为什么从桥上丢下的石头和羽毛在真空中同时落地?

Why do a stone and a feather hit the ground together in vacuum?

自由落体加速度 g=GM/r² 与质量无关,所有物体在真空中以相同加速度下落;羽毛落后只是空气阻力(与形状、面积有关)造成的,真空中没有空气就同时落地。
Free-fall acceleration g=GM/r² is mass-independent; in vacuum everything falls together. A feather lags only because of air resistance, absent in vacuum.
难度 进阶 · 适合 初中(12-15) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source

Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #自由落体 #等效

双缝实验里“观察”为什么会让波坍缩成粒子?

Why does observation in the double-slit experiment collapse the wave into particles?

若用设备分辨光子走哪条缝,就引入了与路径相关的信息(退相干),干涉条纹消失;不测量路径时,概率幅叠加产生明暗条纹。测量本身破坏了相干。
Detecting which slit entangles the photon with path information (decoherence) and kills interference; without path measurement the probability amplitudes add and fringes appear. Measurement destroys coherence.
难度 进阶 · 适合 高中(15-18) CC BY 4.0 · 已核验 · Verified 2026-11-02
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Tonomura 等,《单电子干涉图样的累积演示》,American Journal of Physics 57 (1989)

Tonomura, Endo, Matsuda & Kawasaki, 'Demonstration of Single-Electron Buildup of an Interference Pattern', American Journal of Physics 57 (1989)

#双缝 #退相干 #测量

为什么骑自行车不扶把也不会倒?

Why doesn't a bike fall over even without hands on the bars?

前进时轮子像陀螺,倾斜会触发前轮转向使接触点回到重心下方(陀螺加转向自稳);速度足够时这种自校正盖过不稳,所以能不扶把骑行。
Moving wheels act like gyroscopes; a lean steers the front wheel so the contact point returns under the center of mass. Above a speed this self-correction stabilizes the bike.
难度 进阶 · 适合 小学高段(9-12) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
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Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #自行车 #陀螺

薛定谔猫实验真正想挑战的是什么?

What was Schrodinger's cat experiment really challenging?

它把微观叠加放大到宏观猫的生死,质问“测量何时让叠加坍缩”、以及宏观世界为何看不到叠加——推动了多世界、退相干等诠释的发展。
It blows a microscopic superposition up to a cat's life or death, questioning when measurement collapses a state and why we never see macro superpositions—spurring many-worlds and decoherence views.
难度 进阶 · 适合 小学高段(9-12) CC BY 4.0 · 来源待核验 · Source pending review
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出处备注:著录含书名,但缺版次 / 出版社 / 年份中的一部分,需编辑补全后才能做独立比对。

Schrodinger,《量子力学目前的状况》,Naturwissenschaften 23 (1935)

Schrodinger, 'Die gegenwartige Situation in der Quantenmechanik', Naturwissenschaften 23 (1935)

#薛定谔猫 #诠释 #退相干

为什么从行驶的车里看,近处的树往后跑、远山却几乎不动?

Why do near trees seem to rush backward but distant hills barely move from a moving car?

近处东西在你的视野里角度变化快,所以显得飞快后退;远处山离得远,同样车程造成的角度变化很小,看起来就几乎不动。
Near things change angle in your view quickly, so they seem to rush by; far hills shift angle very little for the same trip, so they look almost still.
难度 入门 · 适合 幼儿(3-6) CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source

Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #相对运动 #透视

为什么热水有时比冷水结冰更快(姆潘巴现象)?

Why can hot water sometimes freeze faster than cold—the Mpemba effect?

这不是普遍定律,但在某些条件下成立:热水蒸发更快减少水量、温差大加速顶部冷却、溶质浓度与容器结霜差异等都可能让较热水先结冰。
Not a universal law, but under some conditions it holds: faster evaporation reduces mass, stronger cooling at the top, and differences in solutes/frost can let hotter water freeze first.
难度 入门 · 适合 大众 CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source

Paul Hewitt,《Conceptual Physics》Pearson 多版

Paul G. Hewitt, Conceptual Physics, Pearson, various editions

#悖论 #姆潘巴 #冻结

薛定谔的猫到底是死是活?

Is Schrodinger's cat dead or alive?

这是思想实验:在没打开盒子看之前,猫被说成“又死又活”的叠加,用来说明量子世界很奇怪。
It is a thought experiment: before you open the box, the cat is described as both alive and dead, showing how odd quantum rules are.
难度 入门 · 适合 幼儿(3-6) CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source

出处备注:著录含书名,但缺版次 / 出版社 / 年份中的一部分,需编辑补全后才能做独立比对。

Schrodinger,《量子力学目前的状况》,Naturwissenschaften 23 (1935)

Schrodinger, 'Die gegenwartige Situation in der Quantenmechanik', Naturwissenschaften 23 (1935)

#薛定谔猫 #叠加 #量子