Can Particles be Quantum Entangled Across Time?

World Science Festival
29 Apr 202435:19

Summary

TLDR本视频脚本深入探讨了量子力学的基本原理,包括量子物理的概率性质、量子与经典世界之间的神秘联系,以及量子纠缠所带来的非局部特性。这些特性不仅是量子物理学的核心,也是现代科技应用的基础。视频还提出了量子力学可能对理解时空本质的影响,引出了量子力学与广义相对论结合的挑战,以及量子力学在解释宏观现象时的局限性。通过精彩的对话,观众将对量子力学的哲学维度、量子概率波、测量问题,以及量子力学与现实本质的关系有更深入的理解。

Takeaways

  • 📚 牛顿的运动定律在宏观世界中非常成功,但在微观世界(分子、原子和亚原子粒子)中失效,这导致了量子力学的发展。
  • 🚀 量子力学的核心特征是概率论,与牛顿决定论的世界观不同,量子力学不预测物体的确切未来状态,而是预测可能性。
  • 🌌 爱因斯坦虽然对量子力学的某些非定域性特征持批评态度,但量子力学已被实验以惊人的精度证实,并用于开发惊人技术。
  • 🤔 量子力学的某些方面,如量子概率和量子纠缠,对我们的日常经验来说仍然是个谜,科学界仍在探索其对现实本质的意义。
  • 🧬 量子纠缠是量子力学中的一种非经典关联,其中两个或多个粒子以一种方式相互关联,以至于一个粒子的量子状态不能独立于其他粒子的状态来描述。
  • ⏳ 量子退相干是解释宏观世界中为何不观察到量子效应的一个重要概念,它涉及粒子与其环境的相互作用,从而抑制量子概率的某些方面。
  • 🔍 量子力学的解释和实验验证仍在进行中,包括探索量子力学如何从描述宇宙内部的系统扩展到描述整个宇宙。
  • 🌐 量子力学可能需要新的科学范式,而量子纠缠可能是理解时空结构的关键,它挑战了我们对经典物理世界的看法。
  • ⚙️ 量子计算机的开发依赖于量子比特之间的纠缠状态,这是量子力学非经典关联的一个实际应用。
  • 📉 海森堡不确定性原理是量子力学的基本原理之一,表明某些物理量(如位置和动量)不能同时被精确知晓。
  • 📈 量子力学的发展和理解对我们未来探索宇宙、开发新技术以及深入理解物理现实具有重要意义。

Q & A

  • 牛顿的运动定律在什么情况下开始失效?

    -牛顿的运动定律在20世纪初科学家开始探索分子、原子和亚原子粒子的新领域时开始失效。在这些微观尺度上,牛顿的预测无法描述观测到的数据。

  • 量子力学与牛顿力学在描述现实方面有何根本不同?

    -量子力学与牛顿力学的根本不同在于量子力学是建立在概率概念上的。在牛顿力学中,给定物体当前的位置和速度,可以通过方程预测其未来的运动。而在量子力学中,虽然我们知道物体当前的状态,但方程提供的是未来可能状态的概率。

  • 为什么在日常生活中我们观察不到量子力学的概率性质?

    -在日常生活的宏观尺度上,与原子和粒子相比,概率分布被扭曲,使得一个结果几乎成为确定的结果,即牛顿力学的结果。但在考虑更小的领域时,概率分布更广泛,使得牛顿力学的结果只是多种可能性中的一种。

  • 爱因斯坦对量子力学的哪些方面持批评态度?

    -爱因斯坦对量子力学中的某些方面持批评态度,特别是它对现实的非决定性描述,即宇宙以一种数学上精确的概率游戏演化,这与爱因斯坦的直觉不符。

  • 量子力学是否是现实的终极理论,还是仅仅是一个过渡性的理论?

    -量子力学目前是描述系统非常精确的理论,但科学家们仍在探索它是否是现实的终极理论,或者它只是一个更基础描述的垫脚石,仍有待发现。

  • 量子力学的发展对我们理解物理宇宙有何深远影响?

    -量子力学的发展对我们理解物理宇宙有深远的影响,因为它提供了一个与日常经验截然不同的世界描述,这要求我们重新考虑物理现象的本质和现实的性质。

  • 量子力学中的双缝实验揭示了什么?

    -量子力学中的双缝实验揭示了粒子具有波动性,即粒子可以像波一样干涉,形成特定的干涉图样。这个实验支持了量子力学中物质被描述为概率波的概念。

  • 量子纠缠是什么,它为何如此重要?

    -量子纠缠是量子力学中的一个现象,其中两个或多个粒子以一种方式相互关联,以至于一个粒子的量子状态不能独立于其他粒子描述。它的重要性在于它挑战了经典物理学中关于局部性的概念,并对我们理解宇宙的基本结构提出了新的问题。

  • 量子退相干是什么,它如何解释宏观世界中的确定性结果?

    -量子退相干是一个过程,其中量子系统的相干性由于与环境的相互作用而丧失,导致量子概率中的干涉项被抑制。这解释了为什么我们在宏观世界中观察到的是确定性结果,而不是量子力学所描述的概率性。

  • 量子力学中的不确定性原理是什么,它对我们理解物理现象有何影响?

    -量子力学中的不确定性原理表明,某些物理量(如位置和动量)不能同时被精确知道。这个原理对我们理解物理现象有根本性的影响,因为它表明在量子尺度上,我们无法像在宏观世界中那样精确预测事件。

  • 量子力学中的多世界解释是什么,它如何改变我们对现实的看法?

    -量子力学中的多世界解释提出,每当一个量子事件发生时,宇宙都会分裂成多个版本,每个可能的事件结果都会在不同的宇宙中实现。这种解释改变了我们对现实的看法,因为它提出现实可能不是单一的,而是由多个并行的宇宙组成。

Outlines

00:00

😀 牛顿力学的误导性

第一段落主要讲述了牛顿力学对科学几百年的影响,以及它在20世纪初对分子、原子和亚原子粒子的预测失败。牛顿的运动定律在日常生活中非常准确,但当科学家探索微观世界时,牛顿的预测不再准确。这导致了量子力学的诞生,这是一种基于概率的新理论框架,与牛顿力学的确定性预测不同,量子力学预测的是事物未来状态的概率。爱因斯坦虽然对量子力学持批评态度,但实验已经证明了量子力学的惊人精确度,并且科学家们利用它开发出了令人惊叹的技术。

05:00

🧐 量子力学对现实的挑战

第二段落探讨了量子力学对人类理解物理宇宙带来的挑战,特别是它与我们的日常经验大相径庭。讨论了量子力学的哲学维度,包括量子概率波和测量问题。强调了物理学家寻求更深层次解释的愿望,即便数学模型能够描述数据,但如果不能提供对宇宙行为的洞察,那么它就没有解释宇宙的本质。

10:01

📚 量子力学的现状与挑战

第三段落讨论了量子力学目前的发展现状和面临的挑战。提到了量子力学的局限性,尤其是在普朗克尺度上,广义相对论与量子场论之间的不协调。强调了哲学家和物理学家之间的合作,以及量子力学中尚未解决的谜题,例如量子概率是否是现实的内在特征,以及量子力学如何从宇宙内部系统的描述扩展到整个宇宙。

15:03

🤔 量子力学的解释难题

第四段落深入探讨了量子力学的解释问题,包括量子退相干和量子纠缠。解释了为什么在宏观层面上我们看到的是确定的结果,而在微观层面上量子力学表现出其概率性。量子退相干是解释宏观世界中量子力学奇异性不显现的一种方式。同时,段落还提到了量子计算的希望和挑战,即如何保持量子比特的纠缠状态,以避免退相干。

20:03

🔬 量子纠缠的历史与发展

第五段落讨论了量子纠缠的历史和概念发展,从1935年薛定谔首次命名开始,到爱因斯坦、波多尔斯基和罗森(EPR)的论文,以及量子纠缠在空间和时间上的性质。强调了量子纠缠的非经典关联,以及它如何挑战我们对物理现实的传统理解。

25:03

🌌 量子纠缠与时空的本质

第六段落进一步探讨了量子纠缠,包括它在时空中的作用和可能的含义。讨论了量子纠缠可能指示时空本身的量子性质,以及这可能如何影响我们对时空结构的理解。还提到了量子纠缠实验,如希伯来大学在2012-2013年进行的纠缠交换实验,展示了即使在不同时间存在的粒子之间也可以存在纠缠关系。

30:04

🎓 量子物理的现实与未来

第七段落总结了量子物理的基础知识,包括量子物理的概率性质、从量子力学到经典世界的转变,以及量子纠缠的非局域性质。强调了量子纠缠可能是时空结构的关键,并且可能是物理学其他领域所建议的时空纠缠性质的证据。最后,鼓励听众继续探索量子现实系列的下一次对话,其中将讨论量子力学的多世界解释等主题。

Mindmap

Keywords

💡牛顿运动定律

牛顿运动定律是艾萨克·牛顿提出的描述物体运动的三个定律,它们定义了物体如何随时间改变其运动状态。在视频中,牛顿运动定律被用来与量子力学中的不确定性和概率性形成对比,展示了从牛顿经典物理学到量子物理学的转变。

💡量子力学

量子力学是20世纪初发展起来的物理理论,它描述了原子和亚原子粒子的行为。与牛顿力学不同,量子力学的核心是概率论,它不预测物体的具体状态,而是预测物体状态的概率。视频中提到量子力学是对我们对物理宇宙理解的最深刻颠覆。

💡概率

在量子力学中,概率是一个基本特征,它描述了量子系统可能状态的发生几率。视频中强调,量子力学中的概率不是测量技术的不足,而是自然界的一个基本方面,这与牛顿力学中的确定性轨迹预测形成了鲜明对比。

💡薛定谔的猫

薛定谔的猫是一个思想实验,用来说明量子力学中的超位置原理和观测对量子系统状态的影响。视频中没有直接提到薛定谔的猫,但它是量子力学中关于概率和观测的一个经典例子。

💡双缝实验

双缝实验是量子力学中一个著名的实验,展示了粒子的波动性质和干涉图样。在视频中,双缝实验用来说明量子力学中的概率波概念,以及如何通过实验观察到与经典物理预测不符的结果。

💡量子纠缠

量子纠缠是量子力学中的一个现象,其中两个或多个粒子以一种方式相互关联,以至于一个粒子的测量会瞬间影响到另一个粒子的状态,无论它们之间相隔多远。视频中讨论了量子纠缠的历史和它对物理现实的影响,以及它如何挑战了我们对空间和时间的传统理解。

💡量子退相干

量子退相干是量子系统与其周围环境相互作用的结果,导致量子系统的相干性和纠缠态的丧失。视频中提到量子退相干可以解释为什么我们在宏观世界中不经常观察到量子效应,因为这些效应被环境的相互作用所抑制。

💡量子计算

量子计算是一种利用量子力学原理进行信息处理的技术。视频中提到量子比特(qubits)的纠缠是构建量子计算机的关键,因为它们允许量子计算机执行比传统计算机更强大的计算。

💡贝尔不等式

贝尔不等式是约翰·贝尔提出的一组数学不等式,用于测试量子力学中的非局域性是否与经典物理学相一致。视频中提到贝尔不等式在量子纠缠实验中的应用,展示了量子力学预测与经典物理学预测之间的差异。

💡量子引力

量子引力是试图将量子力学与广义相对论结合起来的理论,以更全面地描述宇宙的基本力。视频中提到量子引力是当前物理学中的一个研究前沿,它试图解释在极小尺度上,如普朗克尺度,物理现象的行为。

💡多世界解释

多世界解释是量子力学的一种解释,它提出每当量子事件发生时,宇宙都会分裂成多个版本,每个可能的事件结果都发生在不同的宇宙中。视频中提到了这一解释,并暗示它可能是理解量子力学的一种方式。

Highlights

艾萨克·牛顿的洞察为科学设定了数百年的进程,但他的见解在某种程度上也极具误导性。

牛顿的运动定律在日常生活中我们所经历的事物运动中得到了体现,它们定义了物体的位置和速度。

牛顿的算法能够预测现实如何展开,正确预测了月球、行星的位置以及抛出的球的落点。

20世纪初,科学家开始探索分子、原子和亚原子粒子的新领域,牛顿的预测未能描述数据。

量子力学的发现和发展是20世纪20年代晚期科学家们创造的新范式,其核心是概率概念。

量子力学与牛顿力学不同,它不是预测事物将如何发展,而是描述事物发展的概率。

量子力学表明,宇宙以一种数学精确的概率游戏演化,爱因斯坦对此感到不满。

量子概率是现实的一个基本特征,而不是方法的局限。

量子力学在宏观层面上,与我们的直觉和日常经验相符,但在微观层面上,概率分布更广泛。

量子力学的许多问题至今仍未解决,例如量子概率是否是现实的内在特征,或者量子力学是否只是更基本描述的垫脚石。

量子力学是对我们对物理宇宙理解的最深刻冲击,因为它描述的世界与我们的日常生活经验截然不同。

量子力学的哲学维度,包括量子概率波和测量问题,是物理学家探索的重点。

量子力学的局限性和它如何映射到现实世界是当前物理学和哲学研究的热点。

量子力学的100周年纪念在2025年,至今仍存在关于数学如何映射到世界的难题。

量子力学与广义相对论在普朗克尺度上的不兼容性,是当前理论物理学中一个重要的问题。

量子纠缠是量子力学中一个非直观的特性,它表明即使两个系统不再相互作用,它们也不能独立于对方被描述。

量子纠缠可能暗示着时空本身的量子性质,包括时空的量子纠缠关系。

量子力学的非定域性质,即量子纠缠的粒子即使在空间上相隔很远,也能瞬间影响彼此的状态。

量子力学的实验验证了其惊人的精确度,并且科学家已经利用它发展出了令人惊叹的技术。

Transcripts

00:01

[Music]

00:09

[Applause]

00:16

Isaac Newton's insights set the course

00:18

of science for hundreds of years but

00:21

there's a sense in which Newton's

00:23

insights were also deeply misleading

00:26

Newton's famous Laws of Motion codify

00:28

what we all experience in everyday life

00:31

things move and as they do they sweep

00:34

out trajectories defined by position

00:37

where something is and velocity how fast

00:40

and in what direction Something is

00:41

moving indeed reality in this framing

00:45

comprises these very trajectories by

00:49

providing equations to delineate these

00:51

trajectories how the position and

00:53

velocity of an object change over time

00:56

Newton provided an algorithm for

00:58

predicting how reality

01:00

unfolds and the algorithm Works Newton's

01:03

Laws correctly predict where the moon

01:06

should be at any moment where the planet

01:09

should be at any moment where a ball

01:11

should land when

01:13

thrown but in the early part of the 20th

01:16

century as scientists began to probe the

01:19

newly accessible realm of molecules

01:22

atoms and subatomic particles newtonium

01:25

predictions failed to describe the data

01:28

and this failure was not one of f detail

01:30

that might suggest a simple refinement

01:33

to Newton's equations the failure was

01:36

epic suggesting to some that an entirely

01:39

new paradigm might be

01:43

required that intuition proved

01:47

correct and remarkably by the late 1920s

01:51

a single generation of scientists

01:53

produced that new paradigm with the

01:56

discovery and development of quantum

01:59

mechanics

02:01

an essential feature of the quantum

02:03

Paradigm is that the theory is built

02:04

around the concept of

02:07

probability that is unlike the Newtonian

02:10

picture in which we specify how things

02:12

are now and the equations predict how

02:15

they will be later on in the quantum

02:19

picture we specify how things are now

02:21

but the equations do something entirely

02:24

different they dictate the probability

02:27

of how things will be later on and

02:30

according to our best understanding the

02:32

Reliance and probability is not a

02:34

limitation of the approach but rather is

02:37

a fundamental feature of

02:39

reality the universe in a manner that

02:42

Einstein found

02:44

unpalatable evolves according to a

02:46

mathematically precise game of

02:50

chance so why don't we see these

02:53

probabilities in the course of everyday

02:55

life well the large scales of the

02:58

everyday compared to atams and particles

03:00

skew the probabilities making one

03:03

outcome the almost certain outcome and

03:06

that outcome is indeed the Newtonian

03:10

outcome but as we consider smaller

03:12

Realms the probabilities spread more

03:15

broadly rendering the Newtonian outcome

03:18

just one among many possibilities whose

03:21

likelihoods are governed by the

03:22

equations of quantum

03:25

mechanics Einstein may have been the

03:27

most vocal critic of this direction

03:29

physics had taken but even ardin

03:33

proponents have struggled to grasp what

03:36

quantum mechanics really means for the

03:38

nature of reality although experiment

03:41

has confirmed quantum mechanics to

03:43

astounding precision and scientists have

03:46

used it to develop stunning

03:48

Technologies many of those questions are

03:51

still with us today are quantum

03:54

probabilities an intrinsic feature of

03:57

reality or an artifact of the quantum

03:59

for

04:00

formalism how does the world transition

04:03

from the haze of possibilities Allowed

04:06

by the quantum description to the single

04:09

definite reality of common

04:11

experience how do we extend quantum

04:14

mechanics from description of systems

04:16

within the universe to the universe as a

04:18

whole is quantum mechanics The Rock

04:21

Bottom theory of reality or will it

04:23

prove a mere stepping stone to a more

04:25

fundamental description still awaiting

04:29

discovery

04:30

as WE peer into the future insight into

04:34

these questions will be essential for

04:36

navigating the quantum

04:39

Universe good

04:44

afternoon thank

04:48

you all right so our our subject today

04:51

is quantum mechanics and arguably

04:53

Quantom mechanics is really the most

04:56

profound disruption to our understanding

05:00

of the physical universe that our

05:01

species has ever

05:03

encountered and part of the reason for

05:06

that is the description of the world as

05:09

we just saw in the piece and as we will

05:10

explore here today the description of

05:13

the world is so different from our

05:17

everyday experience and in a sense

05:20

perhaps we should not be surprised by

05:23

that because after all our

05:26

minds evolved in order that we could

05:31

survive and survival and the intuition

05:34

that allows us to survive it does not

05:36

need to know about the behavior of

05:39

electrons and atoms and subatomic

05:42

particles this juncture between how we

05:44

experience the world and how we

05:47

understand the world through observation

05:49

and experiment will really be what will

05:52

guide our discussion here today we've

05:54

got a number of wonderful scientists to

05:57

help us think through some of the key

06:00

issues we have Elise Kow we have Sean

06:03

Carol we have Carla relli and let us now

06:06

turn to the first of those

06:10

conversations with Elise koll who is an

06:14

associate professor of philosophy at the

06:17

City University graduate Center and City

06:19

College her research explores the

06:21

philosophical dimensions of quantum

06:23

mechanics caal models as well as

06:25

relativistic and temporal

06:27

entanglement thank you

06:34

so just just to jump right inise I think

06:37

all of us are familiar that you know

06:39

prior to say

06:42

1900 we had a pretty good understanding

06:46

of physics right through the ideas of of

06:48

Newton and Maxwell and so forth and then

06:51

it began to to crumble right and as it

06:55

began to crumble a new paradigm came on

06:58

the scene

07:00

I want to explore that Paradigm but

07:02

you've written on the history of the

07:04

subject and I think many people perhaps

07:07

don't fully appreciate how much of a

07:09

psychological and emotional upheaval

07:13

this time was for the discovers of these

07:16

ideas can you just give us a sense of

07:17

what it was like sure um well I can try

07:20

I've felt that sort of cognitive

07:22

dissonance myself so there's some

07:23

first-person experience but um yeah

07:26

there was a famous speech given by Sir

07:28

Arthur Edington or S not Edington uh

07:31

Lord Kelvin thank you Lord Kelvin um one

07:34

of the guys in the history of physics

07:38

they're all the same yes he said there

07:41

were just a few clouds on the horizon

07:43

and we've nearly solved it all you know

07:45

we have boltzman manian statistical

07:46

mechanics we have Newtonian mechanics um

07:50

we've we've got um Maxwell's

07:52

electromagnetism uh there's just a few

07:54

issues and one of those issues was black

07:56

body radiation and that's just basically

07:59

if you've seen in an oven um whe there

08:01

was a known correlation between the

08:03

color or the heat inside of it and um

08:06

and how it radiated back out and there

08:09

was no good model for it and so uh plank

08:13

uh sort of looked at the the uh

08:15

empirical data and said I don't quite

08:18

know what the underlying story is here

08:20

yet but I can Cobble together a

08:22

mathematical structure I composite uh

08:25

this idea that light acts as though

08:27

quantized um quantized little little

08:30

pieces in bits yeah not just a wave as

08:32

it had been thought um and this captured

08:36

you know the empirical data correctly

08:38

but plank hated it because he said I

08:40

don't know what my own math really means

08:43

and it took until Einstein in 1905 and

08:46

then in 1909 uh to sort of provide that

08:49

background story and Einstein wasn't

08:51

happy with the background story either

08:53

because it required two terms in the

08:56

equation to solve black body reation one

08:58

of the terms was wav like continuous the

09:01

other term had H Plank's constant it was

09:05

quantized it was about bits and there

09:07

they were sitting together in this

09:08

equation uh and that's how we know it to

09:11

be today now is there something odd

09:14

about the idea of not being happy with

09:16

the mathematics after all if the

09:18

mathematics describes the data and

09:21

that's ultimately what physics is meant

09:24

to do why why would someone be unhappy

09:28

with it oh because I think uh we're

09:31

interested in the deeper explanations

09:33

right um or at least that's what

09:35

physicists tend to be drawn to uh and

09:38

mathematical mapping like capturing of

09:40

the phenomena is a part of it surely um

09:44

but how that mathematics is supposed to

09:46

lend insight into the real behavior of

09:49

things um if that's missing then you've

09:51

solved a puzzle but you haven't

09:54

explained the nature of the universe and

09:55

that's sort of the driving uh the

09:58

driving motivation I think for many of

10:01

these and and we'll get into the details

10:02

of you know Quantum probability waves

10:05

and issues like the measurement problem

10:06

just a moment but given that well

10:11

articulated view of what physicists are

10:15

trying to do where would you say we are

10:19

right now today with quantum

10:21

mechanics uh that's a great and large

10:23

question uh so I mean I'm primarily a

10:26

philosopher so I'm I I get sort of this

10:28

perspective uh so don't take it

10:30

personally if I say something you don't

10:32

like um but I think it's actually a

10:35

really exciting time because we're

10:37

seeing exactly the limitations of models

10:39

we've been working with for nearly a

10:41

century now I mean the 100th anniversary

10:43

of quantum mechanics is in

10:45

2025 um and there's still puzzles

10:47

enduring puzzles about what uh how the

10:50

mathematics really maps onto the world

10:52

and how to explain a lot of the data we

10:54

have uh and this gets even more uh

10:57

apparent when we get to the plank scale

10:59

the very small where our very well-

11:01

confirmed theory of general relativity

11:03

no longer sits well with our very wellc

11:05

confirmed theory of uh Quantum fields

11:08

and so on uh and so and the plank scale

11:10

just to give you people a sense of how

11:11

small that is 10 Theus 33 cm is a number

11:16

that we often kick around so it's

11:18

fantastically small yeah extraordinarily

11:20

small um but I don't know it keeps me

11:23

awake at night to think that these two

11:25

theories don't don't play well at that

11:27

level um but it's it's an exciting time

11:30

as a philosopher with with physics

11:32

training

11:34

because there's more engagement between

11:37

philosophers and physicists because

11:39

we're talking about theories of quantum

11:41

gravity and theories of quantum field

11:43

theories and so on that uh not every

11:45

piece of them is empirically uh testable

11:47

or at least we haven't figured out how

11:49

or maybe maybe in principle testable so

11:52

some of this is questions of how

11:54

brilliant are engineering how clever we

11:56

can get about shielding our systems from

11:58

external fields and so on um but part of

12:01

it is just asking can we have a broader

12:03

notion of what evidence we might look

12:05

for can we think about for instance

12:08

whether there are systems we understand

12:09

very well in a different realm of

12:11

physics like hydrodynamics or something

12:13

that might yield insights into how

12:15

Quantum gravitational systems might work

12:18

but how do you an analyze the science of

12:21

a analogy right how do you know when the

12:24

explanation from this one field that's

12:25

well known whether it's really saying

12:28

something about this other unknown uh

12:31

bit of the world or whether it's just

12:33

biasing the way you're describing the

12:36

narrative that you're telling about the

12:37

world and it can go both ways sure so so

12:40

getting in a little bit to the details

12:42

in the background in the Newtonian

12:45

picture if I tell you the initial

12:48

conditions you know the the speed and

12:51

the location from which a ball say is

12:54

thrown the velocity to be more precise

12:56

Newton tells us where it will land and

12:59

quantum mechanics comes along and says

13:02

that's not the case right so in quantum

13:06

mechanics there are many locations where

13:09

say an electron could land given the

13:11

same initial conditions and that leads

13:13

to this idea of a probabilistic

13:17

description of the world where you don't

13:19

say where it's going to land you just

13:21

give the probabilities of where it might

13:23

be so one way that that scientists were

13:27

taken to this picture of matter is of

13:29

course with the famous double slit

13:30

experiment where you know you're firing

13:33

particles at a barrier with two slits

13:35

you'd think that the particles would

13:37

land on the detector screen in two lines

13:40

that are aligned with the two openings

13:43

but when you actually do the experiment

13:45

of course as we now know for over a

13:47

hundred years you don't find just two

13:49

lines on the detector screen in fact you

13:52

find many lines many bands in a very

13:54

particular pattern which scientists were

13:57

able to explain by thinking of particles

14:00

as waves and as the waves hit the two

14:03

openings and they carry on they

14:06

crisscross and they interfere with each

14:08

other and through that interference we

14:11

get a pattern just as in the data if we

14:14

interpret of course the waves as waves

14:15

of probability where the wave is Big

14:17

many of the particles will land where

14:19

the wave is small very few will land so

14:21

this this now takes us to this this new

14:24

paradigm that particles matter should be

14:27

described as undula

14:29

waves of

14:31

probability did it take people a long

14:33

time to accept that change because I

14:37

would consider that I mean we'll talk

14:39

about other things but that's like the

14:41

dominant new idea that comes into the

14:43

story well Brian I'd argue that there

14:45

are many people who still haven't

14:46

accepted that what we what quantum

14:49

mechanics are saying is that we have a

14:51

an irrevocably probabilistic Universe um

14:55

and so there are many interpretations

14:57

that are offered of this mechanics there

14:58

are supposed was to fill this Gap

15:00

explain why it is that the formalism

15:02

that's sort of shared amongst the

15:04

interpretations the sort of core bit of

15:06

explanatory work maybe what you read in

15:09

your quantum mechanics textbooks which

15:11

you all have at home and we'll study

15:13

later this evening right um but H the

15:17

story there is that yeah we get we get

15:19

we have the born rule which is this rule

15:21

that tells us how what sort of

15:22

probability to expect which outcomes

15:24

yeah but no thoroughgoing causal story

15:27

of how we get from point A to exactly

15:29

point B A well- Defined localized spot

15:33

or measurement and that that that story

15:36

that you're referring to would start

15:38

with this new

15:40

probabilistic idea electron 30% here 22%

15:45

there 19% there and so forth go from

15:47

that which we don't experience somehow

15:51

transitioning to when we measure the

15:53

electron we find it at one location it's

15:55

a kind of schematic representation where

15:58

the height of this wave is meant to

16:00

indicate you know the likelihood of the

16:02

particle being at one location or

16:04

another that's the story that we don't

16:05

experience but then we go and measure

16:07

that electron let's just do it together

16:09

3 2 1 measure that electron oo wow that

16:14

felt very powerful to do that but now

16:17

the probability has spiked because now

16:19

we've measured the electron we know it's

16:21

at that particular location how in the

16:24

world do we go from this weird

16:27

probabilistic description

16:29

upon measurement to a definite outcome

16:32

well I uh that is a deeply unfair

16:36

question he's asking me to resolve the

16:38

interpretation problem for you um and

16:41

you know or even just tell us why it's

16:43

so hard yeah well um so first of all I

16:46

just want to clarify something a little

16:48

bit I mean it's true that at the

16:49

macroscopic level of cables and chairs

16:51

and other people we do see what look to

16:54

be definite outcomes but if you're doing

16:57

measurements on smaller systems you do

17:00

you can measure what are called

17:01

interference terms and we call those

17:03

sort of the residue of the wav like

17:06

features of those systems uh and so

17:09

they're there and we're getting better

17:11

at testing like keeping interference

17:13

terms coherent to higher and higher

17:15

levels so the idea is if we had really

17:18

brilliant uh engineers and really good

17:21

shielding we could send an elephant

17:22

through a double slit experiment and see

17:24

the elephant sort of give us a a

17:27

interference pattern on screen um but