Etydhv

Why "Having chlorophyll without photosynthesis is actually very dangerous" and "like living with a bomb"?

Replacing matching entries in one column of a file by another column from a different file

Does Unearthed Arcana render Favored Souls redundant?

Can divisibility rules for digits be generalized to sum of digits

What are the differences between the usage of 'it' and 'they'?

Why Is Death Allowed In the Matrix?

TGV timetables / schedules?

Which models of the Boeing 737 are still in production?

How did the USSR manage to innovate in an environment characterized by government censorship and high bureaucracy?

Email Account under attack (really) - anything I can do?

What is the offset in a seaplane's hull?

Smoothness of finite-dimensional functional calculus

How is the claim "I am in New York only if I am in America" the same as "If I am in New York, then I am in America?

Can I ask the recruiters in my resume to put the reason why I am rejected?

To string or not to string

Watching something be written to a file live with tail

US citizen flying to France today and my passport expires in less than 2 months

In Japanese, what’s the difference between “Tonari ni” (となりに) and “Tsugi” (つぎ)? When would you use one over the other?

What would happen to a modern skyscraper if it rains micro blackholes?

"to be prejudice towards/against someone" vs "to be prejudiced against/towards someone"

can i play a electric guitar through a bass amp?

Dragon forelimb placement

Why do falling prices hurt debtors?

Method of fabrication patents, Is it okay to import from abroad?

Minkowski space

Poincare group vs Galilean groupMinkowski MetricConservation of phase space volume in Rindler space-timeMinkowski Metric SignatureMinkowski metric — why does it follow from the constancy of the speed of light?Space-like pion electromagnetic form factorMinkowski metric: Why does it look like it does?Understanding space-like hyperplanes in Minkowski spaceCan an a distance in Minkowski space, based on a Euclidean plane, be time-like?How to Construct Proper Spherical Coordinates in Minkowski Spacetime?

1

$begingroup$

In Minkowski space, coordinates which satisfy

x²=t²-X²>0

Region of space time is time-like.
If its.

x²=t²-X²<0

Region is space-like.
But if

x²=t²-X²=0

` then its "trajectory of light like particles".

I have understood the first two points about time and space like region but I could not get the third one about "light like particles".
My confusion is about why just light like particles? there are many other particles at quantum level.

quantum-field-theory special-relativity

share|cite|improve this question

asked 27 mins ago

sk9298sk9298

595

New contributor

sk9298 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$endgroup$

add a comment | 

1

$begingroup$

In Minkowski space, coordinates which satisfy

x²=t²-X²>0

Region of space time is time-like.
If its.

x²=t²-X²<0

Region is space-like.
But if

x²=t²-X²=0

` then its "trajectory of light like particles".

I have understood the first two points about time and space like region but I could not get the third one about "light like particles".
My confusion is about why just light like particles? there are many other particles at quantum level.

quantum-field-theory special-relativity

share|cite|improve this question

asked 27 mins ago

sk9298sk9298

595

New contributor

sk9298 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$endgroup$

add a comment | 

$begingroup$

In Minkowski space, coordinates which satisfy

x²=t²-X²>0

Region of space time is time-like.
If its.

x²=t²-X²<0

Region is space-like.
But if

x²=t²-X²=0

` then its "trajectory of light like particles".

I have understood the first two points about time and space like region but I could not get the third one about "light like particles".
My confusion is about why just light like particles? there are many other particles at quantum level.

quantum-field-theory special-relativity

share|cite|improve this question

asked 27 mins ago

sk9298sk9298

595

New contributor

sk9298 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

$endgroup$

share|cite|improve this question

asked 27 mins ago

sk9298sk9298

595

New contributor

sk9298 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|cite|improve this question

asked 27 mins ago

sk9298sk9298

595

New contributor

sk9298 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 27 mins ago

sk9298sk9298

595

New contributor

sk9298 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 27 mins ago

sk9298sk9298

595

2 Answers
2

active

oldest

votes

2

$begingroup$

My confusion is about why just light like particles? there are many other particles at quantum level.

You are correct. The terminology is historical in nature. Light was the first massless particle to be discovered. The terminology “lightlike” was established before any other massless particles were discovered. Once other massless particles were discovered it was shown that they also travel along lightlike geodesics, but by then the term “lightlike” was well established.

An alternative term with the same meaning as “lightlike” is “null”. If you prefer then you can always use “null” and just understand that people saying “lightlike” mean the same thing.

share|cite|improve this answer

answered 17 mins ago

DaleDale

6,5871829

$endgroup$

add a comment | 

1

$begingroup$

Only particles with zero mass can travel between two events which are separated by a light-like distance. The trajectory is called light-like because photons (light) are massless, and historically the first example of a massless particle, as well as the only example in the 1910's. There are other massless particles, like gluons which would also be able to travel between two events separated by a light-like distance.

The reason why only massless particles are able to travel between two events separated by a light-like distance is that it requires you to travel at exactly the speed of light. You can see this by considering the equation $t^2-x^2=0$, this means that $x=pm t$. These equations are with the units such that the speed of light $c=1$. Thus the particle taking this trajectory is travelling at the speed of light.

share|cite|improve this answer

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310

$endgroup$

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
);



);

sk9298 is a new contributor. Be nice, and check out our Code of Conduct.

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%2f470979%2fminkowski-space%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

2

$begingroup$

My confusion is about why just light like particles? there are many other particles at quantum level.

You are correct. The terminology is historical in nature. Light was the first massless particle to be discovered. The terminology “lightlike” was established before any other massless particles were discovered. Once other massless particles were discovered it was shown that they also travel along lightlike geodesics, but by then the term “lightlike” was well established.

An alternative term with the same meaning as “lightlike” is “null”. If you prefer then you can always use “null” and just understand that people saying “lightlike” mean the same thing.

share|cite|improve this answer

answered 17 mins ago

DaleDale

6,5871829

$endgroup$

add a comment | 

2

$begingroup$

My confusion is about why just light like particles? there are many other particles at quantum level.

You are correct. The terminology is historical in nature. Light was the first massless particle to be discovered. The terminology “lightlike” was established before any other massless particles were discovered. Once other massless particles were discovered it was shown that they also travel along lightlike geodesics, but by then the term “lightlike” was well established.

An alternative term with the same meaning as “lightlike” is “null”. If you prefer then you can always use “null” and just understand that people saying “lightlike” mean the same thing.

share|cite|improve this answer

answered 17 mins ago

DaleDale

6,5871829

$endgroup$

add a comment | 

$begingroup$

My confusion is about why just light like particles? there are many other particles at quantum level.

You are correct. The terminology is historical in nature. Light was the first massless particle to be discovered. The terminology “lightlike” was established before any other massless particles were discovered. Once other massless particles were discovered it was shown that they also travel along lightlike geodesics, but by then the term “lightlike” was well established.

An alternative term with the same meaning as “lightlike” is “null”. If you prefer then you can always use “null” and just understand that people saying “lightlike” mean the same thing.

share|cite|improve this answer

answered 17 mins ago

DaleDale

6,5871829

$endgroup$

share|cite|improve this answer

answered 17 mins ago

DaleDale

6,5871829

answered 17 mins ago

DaleDale

6,5871829

answered 17 mins ago

DaleDale

6,5871829

1

$begingroup$

Only particles with zero mass can travel between two events which are separated by a light-like distance. The trajectory is called light-like because photons (light) are massless, and historically the first example of a massless particle, as well as the only example in the 1910's. There are other massless particles, like gluons which would also be able to travel between two events separated by a light-like distance.

The reason why only massless particles are able to travel between two events separated by a light-like distance is that it requires you to travel at exactly the speed of light. You can see this by considering the equation $t^2-x^2=0$, this means that $x=pm t$. These equations are with the units such that the speed of light $c=1$. Thus the particle taking this trajectory is travelling at the speed of light.

share|cite|improve this answer

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310

$endgroup$

add a comment | 

1

$begingroup$

Only particles with zero mass can travel between two events which are separated by a light-like distance. The trajectory is called light-like because photons (light) are massless, and historically the first example of a massless particle, as well as the only example in the 1910's. There are other massless particles, like gluons which would also be able to travel between two events separated by a light-like distance.

The reason why only massless particles are able to travel between two events separated by a light-like distance is that it requires you to travel at exactly the speed of light. You can see this by considering the equation $t^2-x^2=0$, this means that $x=pm t$. These equations are with the units such that the speed of light $c=1$. Thus the particle taking this trajectory is travelling at the speed of light.

share|cite|improve this answer

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310

$endgroup$

add a comment | 

$begingroup$

Only particles with zero mass can travel between two events which are separated by a light-like distance. The trajectory is called light-like because photons (light) are massless, and historically the first example of a massless particle, as well as the only example in the 1910's. There are other massless particles, like gluons which would also be able to travel between two events separated by a light-like distance.

The reason why only massless particles are able to travel between two events separated by a light-like distance is that it requires you to travel at exactly the speed of light. You can see this by considering the equation $t^2-x^2=0$, this means that $x=pm t$. These equations are with the units such that the speed of light $c=1$. Thus the particle taking this trajectory is travelling at the speed of light.

share|cite|improve this answer

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310

$endgroup$

share|cite|improve this answer

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310

answered 21 mins ago

LucashWindowWasherLucashWindowWasher

30310