<p>Consider this graph of the &quot;stretch and squeeze&quot; at Ligo, Hanford of GW150914  (the first gravitational wave detection, and one of the clearest). This shows the numerical relativity model that was fit to the observations, and so looks &quot;cleaner&quot; than the actual observations.</p>
<p><a href="https://i.sstatic.net/sY4p2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/sY4p2.png" alt="enter image description here" /></a></p>
<p>You may think that the part of the graph above the centre line represents a stretch (of about 10^{-21} metres per metre) and the part below is a squeeze.</p>
<p>As the wave train passes each subsequent stretch is a bit more than the previous squeeze, and each squeeze is more than the previous stretch. This is because the intensity of the radiation is increasing.</p>
<p>But overall there is no tendency for the stretches to be more than the squeezes, and after the gravitational wave has passed, there is no residual stretch. Space returns to its neutral metric, just as after an electromagnetic wave has passed, the electromagnetic field returns to its neutral level.</p>
<p>Note that these stretches and squeezes are in a direction that is <em>perpendicular</em> to the direction of propagation of the wave</p>

CC BY-SA 4.0
2023-05-13T22:38:15.520Z
thanks for your explain great notes in your answer, my exact Q: if you look at very first moment of your graph; some region(below center line) completely we have only squeeze regime for many moment! and we do not have any Stretch in that timeline moment?  (it is sound like squeeze and stretch are not a rhythmic scenario for some moments )
Hamidreza Abdollahi
CC BY-SA 4.0
2023-05-14T05:54:24.467Z
I wouldn't look too closely at the start.  Theres not much signal at the start,  look at the actual signal in the middle
James K
CC BY-SA 4.0
2023-05-13T16:24:53.733Z
2023-05-13T16:24:53.733Z
James K
<p>I suspect you still haven't clarified your question sufficiently.</p>
<p>Gravitational waves are transverse so there is no stretching and compression in the direction they are propagating.</p>

CC BY-SA 4.0
2023-05-13T22:47:21.477Z
thanks it is editted
Hamidreza Abdollahi
CC BY-SA 4.0
2023-05-13T15:36:27.770Z
2023-05-13T15:36:27.770Z
ProfRob
<p>When a gravitational wave passes,
do we always have the same amount of stretching and compression?</p>

CC BY-SA 4.0
2023-05-10T21:32:14.400Z
I don't understand the question.  Please clarify.  What do you mean by "squeeze and stretch"?  Do you mean perpendicular and parallel to the direction of the waves?  Do you mean Do you mean the difference in strain between the crest and the trough of the wave?
James K
CC BY-SA 4.0
2023-05-10T21:40:25.213Z
see the example in Wiki of Gravitational-wave : The effect of a plus-polarized gravitational wave on a ring of particles  and The effect of a cross-polarized gravitational wave on a ring of particles https://en.m.wikipedia.org/wiki/Gravitational_wave
Hamidreza Abdollahi
CC BY-SA 4.0
2023-05-10T21:42:23.857Z
by the way , both Squeez and Stretch words, mentioned there in wiki at the "Effect" section.
Hamidreza Abdollahi
CC BY-SA 4.0
2023-05-10T22:36:37.940Z
+1 for a *very interesting and answerable question!* In some cases, pretty much, yes. But for fast merging events they're usually close but not quite equal." But I think you should edit the question and add a clarification, perhaps something like "...do the largest positive and negative excursions of the strain wave have the same absolute value?"
uhoh
CC BY-SA 4.0
2023-05-11T04:28:46.290Z
From what I remember, gravitational observatories detect waves when the two “arms” of the experiment are deformed differently; I think it’s even one of the telltale signs that it *is* indeed a gravitational wave and not something else. But I may be wrong, hence a comment instead of an answer.
Pierre Paquette
CC BY-SA 4.0
2023-05-11T10:14:09.993Z
@uhoh yes that's what i meant, but i need some formula if there exist or any source which dive into this subject...
Hamidreza Abdollahi
CC BY-SA 4.0
2023-05-11T10:16:34.003Z
@PierrePaquette yes we know that , here i want to explore that : length of change in any direction always same? as they pass they effect in any direction , as called squeez and stretch effect. what i asked is ; both effect on strain is same when GW pass through.?
Hamidreza Abdollahi
CC BY-SA 4.0
2023-05-12T01:15:38.840Z
@HamidrezaAbdollahi: Oh! You mean, from one gravitational wave to the next. I get it. The short answer is no: They identify the kind of event by the “strength” of the gravitational wave. More massive objects will cause more stretching.
Pierre Paquette
CC BY-SA 4.0
2023-05-12T21:11:54.427Z
@HamidrezaAbdollahi can you edit your question post (click "edit") and update it to include all of the clarifications that you've provided in comments? Answer authors may not take the time to read through comments - it's only the question post itself that gets answered in Stack Exchange, and there's already one vote to close your question for "Needs details or clarity: This question should include more details and clarify the problem." *Thanks!*
uhoh
<gravitational-waves>
Effect of a passing gravitational wave
Hamidreza Abdollahi
# Effect of a passing gravitational wave

(Asked by: username_0 on 2023-05-10)

When a gravitational wave passes,
do we always have the same amount of stretching and compression?

**Tags:** gravitational-waves
> **Comments:**
> **username_1**: I don't understand the question.  Please clarify.  What do you mean by "squeeze and stretch"?  Do you mean perpendicular and parallel to the direction of the waves?  Do you mean Do you mean the difference in strain between the crest and the trough of the wave?  
> **username_0**: see the example in Wiki of Gravitational-wave : The effect of a plus-polarized gravitational wave on a ring of particles  and The effect of a cross-polarized gravitational wave on a ring of particles https://en.m.wikipedia.org/wiki/Gravitational_wave  
> **username_0**: by the way , both Squeez and Stretch words, mentioned there in wiki at the "Effect" section.  
> **username_2**: +1 for a *very interesting and answerable question!* In some cases, pretty much, yes. But for fast merging events they're usually close but not quite equal." But I think you should edit the question and add a clarification, perhaps something like "...do the largest positive and negative excursions of the strain wave have the same absolute value?"  
> **username_3**: From what I remember, gravitational observatories detect waves when the two “arms” of the experiment are deformed differently; I think it’s even one of the telltale signs that it *is* indeed a gravitational wave and not something else. But I may be wrong, hence a comment instead of an answer.  
> **username_0**: @uhoh yes that's what i meant, but i need some formula if there exist or any source which dive into this subject...  
> **username_0**: @PierrePaquette yes we know that , here i want to explore that : length of change in any direction always same? as they pass they effect in any direction , as called squeez and stretch effect. what i asked is ; both effect on strain is same when GW pass through.?  
> **username_3**: @HamidrezaAbdollahi: Oh! You mean, from one gravitational wave to the next. I get it. The short answer is no: They identify the kind of event by the “strength” of the gravitational wave. More massive objects will cause more stretching.  
> **username_2**: @HamidrezaAbdollahi can you edit your question post (click "edit") and update it to include all of the clarifications that you've provided in comments? Answer authors may not take the time to read through comments - it's only the question post itself that gets answered in Stack Exchange, and there's already one vote to close your question for "Needs details or clarity: This question should include more details and clarify the problem." *Thanks!*  

---

## 2 answers

### Answer by username_1 on 2023-05-13. Score: 2 | Accepted answer

Consider this graph of the "stretch and squeeze" at Ligo, Hanford of GW150914 (the first gravitational wave detection, and one of the clearest). This shows the numerical relativity model that was fit to the observations, and so looks "cleaner" than the actual observations.

[![enter image description here](https://i.sstatic.net/sY4p2.png)](https://i.sstatic.net/sY4p2.png)

You may think that the part of the graph above the centre line represents a stretch (of about 10^{-21} metres per metre) and the part below is a squeeze.

As the wave train passes each subsequent stretch is a bit more than the previous squeeze, and each squeeze is more than the previous stretch. This is because the intensity of the radiation is increasing.

But overall there is no tendency for the stretches to be more than the squeezes, and after the gravitational wave has passed, there is no residual stretch. Space returns to its neutral metric, just as after an electromagnetic wave has passed, the electromagnetic field returns to its neutral level.

Note that these stretches and squeezes are in a direction that is *perpendicular* to the direction of propagation of the wave

> **Comments:**
> **username_0**: thanks for your explain great notes in your answer, my exact Q: if you look at very first moment of your graph; some region(below center line) completely we have only squeeze regime for many moment! and we do not have any Stretch in that timeline moment?  (it is sound like squeeze and stretch are not a rhythmic scenario for some moments )  
> **username_1**: I wouldn't look too closely at the start.  Theres not much signal at the start,  look at the actual signal in the middle  

---

### Answer by username_4 on 2023-05-13. Score: 3

I suspect you still haven't clarified your question sufficiently.

Gravitational waves are transverse so there is no stretching and compression in the direction they are propagating.

> **Comments:**
> **username_0**: thanks it is editted  

---

