<p>This was discussed in a recent paper by an Oxford cosmologist: <a href="https://arxiv.org/abs/1712.07962" rel="nofollow noreferrer">https://arxiv.org/abs/1712.07962</a></p>

<p>It claims that there have already been some detections of negative mass using gravitational lensing:</p>

<p><em>In  fact,  “puzzling  results”  in  clusters  such  as negative masses have been discussed in the literature (Andreon, Punzi, &amp; Grado 2005). For example, Chandra observations of the merging cluster Abell 2034 found hints of a negative mass and  therefore  did  not  plot  those  data  (Kempner,  Sarazin,  &amp; Markevitch  2003),  regions  of  the  mass  profile  in  the  galaxy NGC 4636 yielded “unphysical” negative masses (Johnson et al. 2009), in the NGC 3411 galaxy group the total mass was found  to  decline  with  increasing  radius  –  requiring  material with negative mass (O’Sullivan et al. 2007), measurements of galaxy clusters using the Sloan Digital Sky Survey yielded data that indicate a negative mass in poor clusters with fewer than five galaxies (Hansen et al. 2005), a CMB cluster lensing study found a cluster with “a fairly significant preference for negative mass” (Baxter et al. 2017), and a number of strong and weak gravitational lensing studies have discussed or found indications of negative masses in reconstructed mass distributions (Evans &amp; Witt 2003; Clowe, Gonzalez, &amp; Markevitch 2004; Clowe et al. 2006; Liesenborgs, De Rijcke, &amp; Dejonghe 2006; Diego et al. 2007).</em></p>

CC BY-SA 4.0
2019-03-04T08:49:45.673Z
2019-03-04T08:49:45.673Z
Michael G.
<p>If the negative mass is not inside but outside the positive mass, wouldn't it push light passing by away from it, thus towards the positive mass, which would lead to a perceived higher gravitational lensing effect on the positive mass? If so, then <a href="https://www.spacetelescope.org/news/heic2016/" rel="nofollow noreferrer">https://www.spacetelescope.org/news/heic2016/</a> could maybe partially explained by negative mass halos on those galaxies. Villata apparently has mentioned such a &quot;antigravitational lensing effect&quot;. Conceptually it feels much more natural than most dark matter theories.</p>

CC BY-SA 4.0
2020-10-22T22:40:43.180Z
I did not read the link, but dark matter gravitates. Dark energy behaves like an antigravitating thing.
peterh
CC BY-SA 4.0
2020-10-23T09:16:01.013Z
Wow, negative mass attracts negative mass, positive mass attracts positive mass, but negative mass distracts positive. The result might be as in the source. It is very interesting.
peterh
CC BY-SA 4.0
2020-11-03T02:26:04.467Z
I would think negative mass would do the opposite gravitational lensing of what regular mass does - e.g. act like a concave vs. convex lens.  I also speculate negative mass would repel all things, including itself, so it would generally be spread very thin.  Since positive mass attracts, it is possible the sparse negative mass might gather near positive mass.
Jonathan
CC BY-SA 4.0
2020-10-22T20:23:57.547Z
2020-10-22T20:23:57.547Z
tuexss
<p>Is it possible to verify negative mass with gravitational lensing?  The following video proposes an idea that galaxies are surrounded by negative mass: <a href="https://youtu.be/MZtS7cBMIc4" rel="noreferrer">https://youtu.be/MZtS7cBMIc4</a></p>

<p>Could this be proven or disproven by looking at gravitational lensing of distant galaxies, by looking at Hubble Deep Field images?  I would expect if negative mass surrounded a galaxy, it should cause the opposite effect of the positive mass galaxy.  If there is surrounding negative mass, there should be an “anti” lensing effect just outside the normal lensing effect.  Could someone perform this analysis and confirm or deny that idea?</p>

<p><strong>Edit:</strong> In the following image, and others, I have looked to see if I could see such an effect out further from the source visually, and it is hard to tell.  There are so many galaxies in front that aren't affected by the lensing.  It might take a computer analysis of images surrounding the "ring" effect to see if there is a "radial effect" around the ring.  Most images probably don't show enough of the surrounding area to where the radial effect as predicted in the paper <a href="https://arxiv.org/abs/1305.5037" rel="noreferrer">Izumi et al. (2013)</a> would be apparent.  If this is present, I would think it indicates negative mass surrounding the positive mass, and would be a huge discovery confirming negative mass!  If absent, it would likely show that there is at least not a significant amount of negative mass clustered around the galaxies (wouldn't be a total disproof of negative mass).  </p>

<p>Image from: <a href="https://www.flickr.com/photos/mvannorden/8276107136" rel="noreferrer">Galaxies - Gravitational Lensing</a>
<a href="https://i.sstatic.net/CmxDg.jpg" rel="noreferrer"><img src="https://i.sstatic.net/CmxDg.jpg" alt="Galaxies - Gravitational Lensing"></a></p>

CC BY-SA 4.0
2019-02-22T15:01:16.693Z
Did you come from the Action Lab video? Jokes aside, fringe youtube videos rarely represent the state of the art in science. Negative masses are not predicted or admitted by any physical theory I know of. That's different for imaginary masses, whose tachyons are admitted by GR, but violate other physics.
AtmosphericPrisonEscape
CC BY-SA 4.0
2019-02-22T16:04:25.107Z
@AtmosphericPrisonEscape - Actually yes . I was thinking if it is out there as the referenced video discusses around galaxies, we should be able to see it with gravitational lensing.  This may be a good way to prove or disprove it.
Jonathan
CC BY-SA 4.0
2019-02-22T16:34:56.393Z
First you'd have to develop a theory of how GR applies to negative mass.  SInce that can't happen, no you can't test via grav lensing.
Carl Witthoft
CC BY-SA 4.0
2019-02-22T17:13:37.977Z
@CarlWitthoft Afaik [GR can describe negative mass](https://en.wikipedia.org/wiki/Negative_mass#In_general_relativity): *"All of these are violations of one or another variant of the positive energy condition of Einstein's general theory of relativity; however, the positive energy condition is not a required condition for the mathematical consistency of the theory."* Thus, the positive energy condition is simply a postulate in the GR and its math would work even without it.
peterh
CC BY-SA 4.0
2019-02-22T19:40:46.740Z
@peterh: Many things are possible in consistent theories, which then disagree with observations.
AtmosphericPrisonEscape
CC BY-SA 4.0
2019-02-23T20:17:14.593Z
@AtmosphericPrisonEscape It is true, but non sequitur. If negative mass would exist, and it would behave as the GR math describes it, and there would be enough negative mass in the Universe to detect it, then we could find it with gravitational lensing. Btw, I am not sure, but AFAIK the dark energy behaves like a roughly constantly distributed, negative mass permeating the whole Universe.
peterh
CC BY-SA 4.0
2019-02-23T23:55:07.903Z
Cornell University has a good article https://arxiv.org/abs/1305.5037
Max0815
CC BY-SA 4.0
2019-02-24T21:12:47.100Z
@mistertribs It looks like gravitational lensing is indeed a way to search for negative mass!
Jonathan
CC BY-SA 4.0
2019-02-25T23:31:46.573Z
Whoever voted to close this question *because it's about Earth Science* needs to explain how gravitational lensing and negative mass are Earth Science matters. Or perhaps a moderator needs to investigate the frivolous or incompetent use of VTC's...
Chappo Hasn't Forgotten
CC BY-SA 4.0
2019-03-03T21:02:19.927Z
@peterh I'd never thought of that before, but that's interesting and sounds legit.  Evenly spread out negative mass would behave just like dark energy . . . but, wouldn't that negative mass attract itself creating lumpiness.   It's the uniform spreading that suggests it's a field not particles (er, I think)  Or, maybe not.   Nevermind.   https://physics.stackexchange.com/questions/44934/does-matter-with-negative-mass-exist
userLTK
<galaxy><gravity><hubble-telescope><gravitational-lensing>
Is gravitational lensing a good way to search for negative mass?
Jonathan
# Is gravitational lensing a good way to search for negative mass?

(Asked by: username_0 on 2019-02-22)

Is it possible to verify negative mass with gravitational lensing? The following video proposes an idea that galaxies are surrounded by negative mass: <https://youtu.be/MZtS7cBMIc4>

Could this be proven or disproven by looking at gravitational lensing of distant galaxies, by looking at Hubble Deep Field images? I would expect if negative mass surrounded a galaxy, it should cause the opposite effect of the positive mass galaxy. If there is surrounding negative mass, there should be an “anti” lensing effect just outside the normal lensing effect. Could someone perform this analysis and confirm or deny that idea?

**Edit:** In the following image, and others, I have looked to see if I could see such an effect out further from the source visually, and it is hard to tell. There are so many galaxies in front that aren't affected by the lensing. It might take a computer analysis of images surrounding the "ring" effect to see if there is a "radial effect" around the ring. Most images probably don't show enough of the surrounding area to where the radial effect as predicted in the paper [Izumi et al. (2013)](https://arxiv.org/abs/1305.5037) would be apparent. If this is present, I would think it indicates negative mass surrounding the positive mass, and would be a huge discovery confirming negative mass! If absent, it would likely show that there is at least not a significant amount of negative mass clustered around the galaxies (wouldn't be a total disproof of negative mass).

Image from: [Galaxies - Gravitational Lensing](https://www.flickr.com/photos/mvannorden/8276107136)
[![Galaxies - Gravitational Lensing](https://i.sstatic.net/CmxDg.jpg)](https://i.sstatic.net/CmxDg.jpg)

**Tags:** galaxy, gravity, hubble-telescope, gravitational-lensing

> **Comments:**
> **username_1**: Did you come from the Action Lab video? Jokes aside, fringe youtube videos rarely represent the state of the art in science. Negative masses are not predicted or admitted by any physical theory I know of. That's different for imaginary masses, whose tachyons are admitted by GR, but violate other physics.  
> **username_0**: @username_1 - Actually yes . I was thinking if it is out there as the referenced video discusses around galaxies, we should be able to see it with gravitational lensing.  This may be a good way to prove or disprove it.  
> **username_2**: First you'd have to develop a theory of how GR applies to negative mass.  SInce that can't happen, no you can't test via grav lensing.  
> **username_3**: @username_2 Afaik [GR can describe negative mass](https://en.wikipedia.org/wiki/Negative_mass#In_general_relativity): *"All of these are violations of one or another variant of the positive energy condition of Einstein's general theory of relativity; however, the positive energy condition is not a required condition for the mathematical consistency of the theory."* Thus, the positive energy condition is simply a postulate in the GR and its math would work even without it.  
> **username_1**: @username_3: Many things are possible in consistent theories, which then disagree with observations.  
> **username_3**: @username_1 It is true, but non sequitur. If negative mass would exist, and it would behave as the GR math describes it, and there would be enough negative mass in the Universe to detect it, then we could find it with gravitational lensing. Btw, I am not sure, but AFAIK the dark energy behaves like a roughly constantly distributed, negative mass permeating the whole Universe.  
> **username_4**: Cornell University has a good article https://arxiv.org/abs/1305.5037  
> **username_0**: @mistertribs It looks like gravitational lensing is indeed a way to search for negative mass!  
> **username_5**: Whoever voted to close this question *because it's about Earth Science* needs to explain how gravitational lensing and negative mass are Earth Science matters. Or perhaps a moderator needs to investigate the frivolous or incompetent use of VTC's...  
> **username_6**: @username_3 I'd never thought of that before, but that's interesting and sounds legit.  Evenly spread out negative mass would behave just like dark energy . . . but, wouldn't that negative mass attract itself creating lumpiness.   It's the uniform spreading that suggests it's a field not particles (er, I think)  Or, maybe not.   Nevermind.   https://physics.stackexchange.com/questions/44934/does-matter-with-negative-mass-exist  

---

## 2 answers

### Answer by username_7 on 2019-03-04. Score: 3 | Accepted answer

This was discussed in a recent paper by an Oxford cosmologist: <https://arxiv.org/abs/1712.07962>

It claims that there have already been some detections of negative mass using gravitational lensing:

*In fact, “puzzling results” in clusters such as negative masses have been discussed in the literature (Andreon, Punzi, & Grado 2005). For example, Chandra observations of the merging cluster Abell 2034 found hints of a negative mass and therefore did not plot those data (Kempner, Sarazin, & Markevitch 2003), regions of the mass profile in the galaxy NGC 4636 yielded “unphysical” negative masses (Johnson et al. 2009), in the NGC 3411 galaxy group the total mass was found to decline with increasing radius – requiring material with negative mass (O’Sullivan et al. 2007), measurements of galaxy clusters using the Sloan Digital Sky Survey yielded data that indicate a negative mass in poor clusters with fewer than five galaxies (Hansen et al. 2005), a CMB cluster lensing study found a cluster with “a fairly significant preference for negative mass” (Baxter et al. 2017), and a number of strong and weak gravitational lensing studies have discussed or found indications of negative masses in reconstructed mass distributions (Evans & Witt 2003; Clowe, Gonzalez, & Markevitch 2004; Clowe et al. 2006; Liesenborgs, De Rijcke, & Dejonghe 2006; Diego et al. 2007).*


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### Answer by username_8 on 2020-10-22. Score: 2

If the negative mass is not inside but outside the positive mass, wouldn't it push light passing by away from it, thus towards the positive mass, which would lead to a perceived higher gravitational lensing effect on the positive mass? If so, then <https://www.spacetelescope.org/news/heic2016/> could maybe partially explained by negative mass halos on those galaxies. Villata apparently has mentioned such a "antigravitational lensing effect". Conceptually it feels much more natural than most dark matter theories.

> **Comments:**
> **username_3**: I did not read the link, but dark matter gravitates. Dark energy behaves like an antigravitating thing.  
> **username_3**: Wow, negative mass attracts negative mass, positive mass attracts positive mass, but negative mass distracts positive. The result might be as in the source. It is very interesting.  
> **username_0**: I would think negative mass would do the opposite gravitational lensing of what regular mass does - e.g. act like a concave vs. convex lens.  I also speculate negative mass would repel all things, including itself, so it would generally be spread very thin.  Since positive mass attracts, it is possible the sparse negative mass might gather near positive mass.  

---

