Gdtyjr

Co-worker team leader wants to inject the crap software product of his friends into our development. What should I say to our common boss?

Playing ONE triplet (not three)

validation vs test vs training accuracy, which one to compare for claiming overfit?

Is this animal really missing?

What to do when during a meeting client people start to fight (even physically) with each others?

Why doesn't the EU now just force the UK to choose between referendum and no-deal?

The three point beverage

infinitive telling the purpose

My story is written in English, but is set in my home country. What language should I use for the dialogue?

Should I tell my boss the work he did was worthless

Is King K. Rool's down throw to up-special a true combo?

Confusion with the nameplate of an induction motor

What is the probability somebody's birthday is the day before mine?

Plywood subfloor won't screw down in a trailer home

Silly Sally's Movie

Potentiometer like component

Is going from continuous data to categorical always wrong?

Replacing Windows 7 security updates with anti-virus?

Rejected in 4th interview round citing insufficient years of experience

How does airport security verify that you can carry a battery bank over 100 Wh?

Prove that the total distance is minimised (when travelling across the longest path)

Sword in the Stone story where the sword was held in place by electromagnets

Word for a person who has no opinion about whether god exists

what does the apostrophe mean in this notation?

Time-reversing a quantum computation: what does this mean for the future of physics and is it considered to be time travel?

Why does the low entropy at the big bang require an explanation? (cosmological arrow of time)Time Reversal Invariance in Quantum MechanicsSecond law of thermodynamics and the arrow of time: why isn't time considered fundamental?Time-reversed twin paradoxWhat does it mean to say that “remembering the future and not the past?”Does conservation of information mean that the direction of causality is arbitrary?Demystifying time-reversal symmetry in physicsreverse entropy, reverse causality and physical lawsWhat goes wrong, theoretically, when we reverse time?Are Mirrored Universes With Opposing Directions of Time Theoretically possible?

2

1

$begingroup$

Today, researchers have reversed time in a quantum computer (maybe violating the second law of thermodynamics). So, What does that mean for the future of physics? and is this considered a time travel?

Further information:

• "Arrow of time and its reversal on the IBM quantum computer" (2019-03-13)




• "Physicists reverse time using quantum computer" (2019-03-13)

quantum-mechanics thermodynamics quantum-entanglement time-reversal-symmetry arrow-of-time

share|cite|improve this question

edited 1 hour ago

Qmechanic♦

106k121941218

asked 2 hours ago

Omar Einstein Omar Einstein

12514

$endgroup$

add a comment | 

2

1

$begingroup$

Today, researchers have reversed time in a quantum computer (maybe violating the second law of thermodynamics). So, What does that mean for the future of physics? and is this considered a time travel?

Further information:

• "Arrow of time and its reversal on the IBM quantum computer" (2019-03-13)




• "Physicists reverse time using quantum computer" (2019-03-13)

quantum-mechanics thermodynamics quantum-entanglement time-reversal-symmetry arrow-of-time

share|cite|improve this question

edited 1 hour ago

Qmechanic♦

106k121941218

asked 2 hours ago

Omar Einstein Omar Einstein

12514

$endgroup$

add a comment | 

$begingroup$

Today, researchers have reversed time in a quantum computer (maybe violating the second law of thermodynamics). So, What does that mean for the future of physics? and is this considered a time travel?

Further information:

• "Arrow of time and its reversal on the IBM quantum computer" (2019-03-13)




• "Physicists reverse time using quantum computer" (2019-03-13)

quantum-mechanics thermodynamics quantum-entanglement time-reversal-symmetry arrow-of-time

share|cite|improve this question

edited 1 hour ago

Qmechanic♦

106k121941218

asked 2 hours ago

Omar Einstein Omar Einstein

12514

$endgroup$

share|cite|improve this question

edited 1 hour ago

Qmechanic♦

106k121941218

asked 2 hours ago

Omar Einstein Omar Einstein

12514

share|cite|improve this question

edited 1 hour ago

Qmechanic♦

106k121941218

asked 2 hours ago

Omar Einstein Omar Einstein

12514

edited 1 hour ago

Qmechanic♦

106k121941218

edited 1 hour ago

Qmechanic♦

106k121941218

asked 2 hours ago

Omar Einstein Omar Einstein

12514

asked 2 hours ago

Omar Einstein Omar Einstein

12514

2 Answers
2

active

oldest

votes

5

$begingroup$

They did not reverse time, they reversed the "arrow of time", meaning that time continued forward but entropy decreased a little, for a moment. Small temporary violations of the second law happens spontaneously all the time on a microscopic scale, wherever the thermal energy comes together in just the right way to be absorbed into an atom or molecule. It is the same thing as "wind assembles fragments back into unbroken object" except that the macroscopic version is so unlikely as to never actually happen.

In this case a quantum computer performed an entropy-decreasing operation. Basically they simulated one of those unlikely entropy-decreasing fluctuations, and because quantum computers utilize coherent quantum states, the simulation itself involved a decrease in entropy. But it was not a fluctuation in the quantum computer, the quantum computer was steered by careful control along the reverse path.

This method will not be used to raise the dead, unspill cups of coffee, take back stupid actions, or any of the other practical applications of reversing the arrow of time, because it can only be applied to quantum systems that were completely under external observation and control from the beginning.

share|cite|improve this answer

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

$endgroup$

add a comment | 

1

$begingroup$

It just means they can make a couple of quits go back to the state they were originally in, and they can do this in a determinable way. In that very small universe all the EM forces, and EM forces essentially determine time (like we have a gazillion or infinite number of EM forces in our universe that determine time), went to a state they had previously been in, this would be impossible in our bigger universe. No it's not time travel, its just physicists controlling a very small universe.

share|cite|improve this answer

answered 1 hour ago

PhysicsDavePhysicsDave

95847

$endgroup$

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function ()
return StackExchange.using("mathjaxEditing", function ()
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
);
);
, "mathjax-editing");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "151"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fphysics.stackexchange.com%2fquestions%2f466335%2ftime-reversing-a-quantum-computation-what-does-this-mean-for-the-future-of-phys%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

5

$begingroup$

They did not reverse time, they reversed the "arrow of time", meaning that time continued forward but entropy decreased a little, for a moment. Small temporary violations of the second law happens spontaneously all the time on a microscopic scale, wherever the thermal energy comes together in just the right way to be absorbed into an atom or molecule. It is the same thing as "wind assembles fragments back into unbroken object" except that the macroscopic version is so unlikely as to never actually happen.

In this case a quantum computer performed an entropy-decreasing operation. Basically they simulated one of those unlikely entropy-decreasing fluctuations, and because quantum computers utilize coherent quantum states, the simulation itself involved a decrease in entropy. But it was not a fluctuation in the quantum computer, the quantum computer was steered by careful control along the reverse path.

This method will not be used to raise the dead, unspill cups of coffee, take back stupid actions, or any of the other practical applications of reversing the arrow of time, because it can only be applied to quantum systems that were completely under external observation and control from the beginning.

share|cite|improve this answer

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

$endgroup$

add a comment | 

5

$begingroup$

They did not reverse time, they reversed the "arrow of time", meaning that time continued forward but entropy decreased a little, for a moment. Small temporary violations of the second law happens spontaneously all the time on a microscopic scale, wherever the thermal energy comes together in just the right way to be absorbed into an atom or molecule. It is the same thing as "wind assembles fragments back into unbroken object" except that the macroscopic version is so unlikely as to never actually happen.

In this case a quantum computer performed an entropy-decreasing operation. Basically they simulated one of those unlikely entropy-decreasing fluctuations, and because quantum computers utilize coherent quantum states, the simulation itself involved a decrease in entropy. But it was not a fluctuation in the quantum computer, the quantum computer was steered by careful control along the reverse path.

This method will not be used to raise the dead, unspill cups of coffee, take back stupid actions, or any of the other practical applications of reversing the arrow of time, because it can only be applied to quantum systems that were completely under external observation and control from the beginning.

share|cite|improve this answer

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

$endgroup$

add a comment | 

$begingroup$

They did not reverse time, they reversed the "arrow of time", meaning that time continued forward but entropy decreased a little, for a moment. Small temporary violations of the second law happens spontaneously all the time on a microscopic scale, wherever the thermal energy comes together in just the right way to be absorbed into an atom or molecule. It is the same thing as "wind assembles fragments back into unbroken object" except that the macroscopic version is so unlikely as to never actually happen.

In this case a quantum computer performed an entropy-decreasing operation. Basically they simulated one of those unlikely entropy-decreasing fluctuations, and because quantum computers utilize coherent quantum states, the simulation itself involved a decrease in entropy. But it was not a fluctuation in the quantum computer, the quantum computer was steered by careful control along the reverse path.

This method will not be used to raise the dead, unspill cups of coffee, take back stupid actions, or any of the other practical applications of reversing the arrow of time, because it can only be applied to quantum systems that were completely under external observation and control from the beginning.

share|cite|improve this answer

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

$endgroup$

share|cite|improve this answer

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

answered 48 mins ago

Mitchell PorterMitchell Porter

7,77011343

1

$begingroup$

It just means they can make a couple of quits go back to the state they were originally in, and they can do this in a determinable way. In that very small universe all the EM forces, and EM forces essentially determine time (like we have a gazillion or infinite number of EM forces in our universe that determine time), went to a state they had previously been in, this would be impossible in our bigger universe. No it's not time travel, its just physicists controlling a very small universe.

share|cite|improve this answer

answered 1 hour ago

PhysicsDavePhysicsDave

95847

$endgroup$

add a comment | 

1

$begingroup$

It just means they can make a couple of quits go back to the state they were originally in, and they can do this in a determinable way. In that very small universe all the EM forces, and EM forces essentially determine time (like we have a gazillion or infinite number of EM forces in our universe that determine time), went to a state they had previously been in, this would be impossible in our bigger universe. No it's not time travel, its just physicists controlling a very small universe.

share|cite|improve this answer

answered 1 hour ago

PhysicsDavePhysicsDave

95847

$endgroup$

add a comment | 

$begingroup$

It just means they can make a couple of quits go back to the state they were originally in, and they can do this in a determinable way. In that very small universe all the EM forces, and EM forces essentially determine time (like we have a gazillion or infinite number of EM forces in our universe that determine time), went to a state they had previously been in, this would be impossible in our bigger universe. No it's not time travel, its just physicists controlling a very small universe.

share|cite|improve this answer

answered 1 hour ago

PhysicsDavePhysicsDave

95847

$endgroup$

share|cite|improve this answer

answered 1 hour ago

PhysicsDavePhysicsDave

95847

answered 1 hour ago

PhysicsDavePhysicsDave

95847

answered 1 hour ago

PhysicsDavePhysicsDave

95847