# How does gravity react with anti matter?
**URL:** https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983
**Category:** Factual Questions
**Created:** [February 4, 2017, 3:14pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983 "2017-02-04T15:14:05Z")
**Posts on this page:** 20
**Page:** 2
### Author:  [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)
#### Post date: [September 27, 2023, 6:07pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/21 "2023-09-27T18:07:49Z")
> [@FlikTheBlue](#):
>
> ETA: I’m not sure why the link looks like that rather than the typical link to an article. Is there a way of correcting that?
Evidently not at least while I’m on my phone. Some urls have a format that fools Discourse’s gizmo that generates preview boxes.
On a pc I could fiddle with it enough to succeed maybe.
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### Author:  [@gnoitall](https://boards.straightdope.com/u/gnoitall)
#### Post date: [September 27, 2023, 6:15pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/22 "2023-09-27T18:15:19Z")
So, no pushing negaspheres with tractor beams.
How could you be so wrong, “Doc” Smith?
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 27, 2023, 10:52pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/23 "2023-09-27T22:52:55Z")
> [@FlikTheBlue](#):
>
> We finally have some experimental evidence to answer the question.
We’ve had experimental evidence for a long time. It’s nice that the new experiments agree with the old ones, but it’s hardly shocking.
And @gnoitall , Doc Smith’s negaspheres were always a weird conflation of the notions of negative mass, antimatter, and black holes. Though I do admire the sheer chutzpah in describing the interaction between a planet and a planet-sized negasphere as resulting in nothing but “a gentle puff of gamma rays”.
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### Author:  [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)
#### Post date: [September 27, 2023, 11:20pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/24 "2023-09-27T23:20:13Z")
> [@gnoitall](#):
>
> How could you be so wrong, “Doc” Smith?
I’ll bet the answer is somewhere in the physics of inertialess mass that allows FTL travel without any pesky “jumps” or “wormholes”.
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### Author:  [@Babale](https://boards.straightdope.com/u/Babale)
#### Post date: [September 28, 2023, 12:38am UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/25 "2023-09-28T00:38:08Z")
Who is Doc Smith, what’s a Negasphere, and how did Doc Smith get one the size of a planet?
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [September 28, 2023, 12:53am UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/26 "2023-09-28T00:53:36Z")
E. E. Smith, author of the Lensman books, classics of space opera science fiction. And also (indirectly) the origin of Qadgop the Mercotan.
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### Author:  [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)
#### Post date: [September 28, 2023, 2:20am UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/27 "2023-09-28T02:20:42Z")
Smith pretty much invented the concept “space opera”. The _Lensman_ series came in second place for the Hugo award for best all time sci-fi series (lost to Asimov’s _Foundation_ series).
> **[Lensman series](https://en.wikipedia.org/wiki/Lensman_series)**
>
> The Lensman series is a series of science fiction novels by American author E. E. "Doc" Smith. It was a runner-up for the 1966 Hugo award for Best All-Time Series, losing to the Foundation series by Isaac Asimov.
> The series begins with Triplanetary, beginning two billion years before the present time and continuing into the near future. The universe has no life-forms aside from the ancient Arisians, and few planets besides the Arisians' native world. The peaceful Arisians have foregone physical ...
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### Author:  [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)
#### Post date: [September 28, 2023, 2:26am UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/28 "2023-09-28T02:26:34Z")
> [@Chronos](#):
>
> as resulting in nothing but “a gentle puff of gamma rays”.
Sorta Gharlane of Eddore’s farts.
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### Author:  [@markn\_1](https://boards.straightdope.com/u/markn_1)
#### Post date: [September 28, 2023, 3:23am UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/29 "2023-09-28T03:23:00Z")
Oh, I thought we were talking about a different Doc Smith.
_Oh, the pain! The pain!_
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### Author:  [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)
#### Post date: [September 28, 2023, 2:37pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/30 "2023-09-28T14:37:38Z")
Hey, my creator did the best he could with the science of the time. He started writing that stuff in 1919 after all. That’s also the year he got his chemical engineering Ph.D.
“Qadgop the Mercotan slithered flatly around the after-bulge of the tranship. One claw dug into the meters-thick armor of pure neutronium, then another. Its terrible xmex-like snout locked on. Its zymolosely polydactile tongue crunched out, crashed down, rasped across. Slurp! Slurp! At each abrasive stroke the groove in the tranship’s plating deepened and Qadgop leered more fiercely. Fools! Did they think that the airlessness of absolute space, the heatlessness of absolute zero, the yieldlessness of absolute neutronium, could stop QADGOP THE MERCOTAN? And the stowaway, that human wench Cynthia, cowering in helpless terror just beyond this thin and fragile wall…”
BTW, Cynthia (the Mrs.) and I are still together!
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### Author:  [@gnoitall](https://boards.straightdope.com/u/gnoitall)
#### Post date: [September 28, 2023, 3:10pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/31 "2023-09-28T15:10:04Z")
I’m glad she appreciates that you consider her worth the effort to rasp-slurp your way through centimeters (I guess) of neutronium to get to her.
The point about “negaspheres” is that Smith’s _Lensman_ stories envisioned a substance called negative matter which would annihilate an equal mass of normal matter. (Possibly influenced by the discovery of real-life antimatter in contemporary physics.)
Negaspheres were simply spheres of assorted sizes (from fist-size to whole planets) of negative matter.
However, negative matter was always pitch black. More relevantly, it had negative mass, so reacted to gravity opposite to the behavior of normal matter.
“Tractor beams” were another Smith invention, and were beams of force that could attract, grasp, or repel matter. (They’re pretty much ubiquitous in SF now.)
The anti-mass phenomenon of a negasphere also affected tractor beams: the attraction setting of a tractor beam actually repelled a negasphere, and switching a tractor beam to repel a negasphere would draw it to you.
That was a lot of off-topic setup for a dumb joke; I apologize for it. I know we have a lot of E. E. “Doc” Smith fans in the community, but that doesn’t really justify an “inside joke” based on 75-year-old space opera tropes.
We return you now to our regularly scheduled real-life physics discussion.
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### Author:  [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)
#### Post date: [September 28, 2023, 3:15pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/32 "2023-09-28T15:15:57Z")
> [@gnoitall](#):
>
> I know we have a lot of E. E. “Doc” Smith fans in the community, but that doesn’t really justify an “inside joke” based on 75-year-old space opera tropes.
Of course it justifies such a joke! It enabled us to fight ignorance and raise awareness about space operas and for me to pointlessly pontificate on precious pearls of prescience. Or something.
OK, carry on with physics then.
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### Author:  [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)
#### Post date: [September 28, 2023, 4:25pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/33 "2023-09-28T16:25:13Z")
This from the Times (unpaywalled) seems to answer the OP: [https://www.nytimes.com/2023/09/27/science/physics-universe-antimatter.html?unlocked\_article\_code=g0-4d\_68hpj7-\_dlDJIkIzkK9qZkVYq4nnLeV6ZptAzcEawra4Ue8rfD4as5IXbDsFhClnsGTRzVKXkv9JM1AlZR88pii1u\_xSRJ9imsWz2N-kBpqATGypoTyToxSj9PeWWk2UvzHEtlfkil3VJhKrZyf7b\_qvx4AwL8T1s\_xq667UkADslLxnhWKv70Z\_VE21NubUmW7WnPQGktjnsENZu-VzyIH3\_PWl-vXrITZb5BO3jrVoykM0bfZNSvNwWNi2VjREOTI\_9eIPzsp7er5Xfwb3Z9IYqH0SN0E-3XLaSb6sOeWAFcM3rBkuxjSMsBnULacuF67x1rb8uvDHSoquq7XbxJ&smid=url-share](https://www.nytimes.com/2023/09/27/science/physics-universe-antimatter.html?unlocked_article_code=g0-4d_68hpj7-_dlDJIkIzkK9qZkVYq4nnLeV6ZptAzcEawra4Ue8rfD4as5IXbDsFhClnsGTRzVKXkv9JM1AlZR88pii1u_xSRJ9imsWz2N-kBpqATGypoTyToxSj9PeWWk2UvzHEtlfkil3VJhKrZyf7b_qvx4AwL8T1s_xq667UkADslLxnhWKv70Z_VE21NubUmW7WnPQGktjnsENZu-VzyIH3_PWl-vXrITZb5BO3jrVoykM0bfZNSvNwWNi2VjREOTI_9eIPzsp7er5Xfwb3Z9IYqH0SN0E-3XLaSb6sOeWAFcM3rBkuxjSMsBnULacuF67x1rb8uvDHSoquq7XbxJ&smid=url-share)
Bottom line: anti-hydrogen atoms (anti-atoms?) fall in a gravitational filed at the same rate as hydrogen atoms.
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### Author:  [@md-2000](https://boards.straightdope.com/u/md-2000)
#### Post date: [September 28, 2023, 7:59pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/34 "2023-09-28T19:59:21Z")
Or this article too:
> **[Antimatter Levitation Debunked: Groundbreaking CERN Experiment Reveals...](https://scitechdaily.com/antimatter-levitation-debunked-groundbreaking-cern-experiment-reveals-gravitys-pull-on-antihydrogen/)**
>
> Experiment at CERN eliminates the possibility that antimatter is repulsed by gravity. CERN's ALPHA collaboration has experimentally confirmed that antihydrogen is pulled down by gravity, negating the concept of antimatter levitation and aligning with...
(Result of Post#9 experiment?)
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### Author:  [@Pasta](https://boards.straightdope.com/u/Pasta)
#### Post date: [September 28, 2023, 8:37pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/35 "2023-09-28T20:37:34Z")
> [@Pasta](#):
>
> Here’s [a post from a past thread](http://boards.straightdope.com/sdmb/showpost.php?p=17702886&postcount=22) in which I quote posts from past threads with some discussion of this. To add:
I noticed that the 2017-era discussion upthread included a link to a post from 2014, but that that link doesn’t work after the migration of the forum’s backend. [The updated link](https://boards.straightdope.com/t/would-an-object-made-of-antimatter-reflect-light/697236/22) is here, in case anyone is trying to follow the 2017-era discussion. (The linked 2014 post also has now-broken links, but I didn’t try to figure those out.)
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### Author:  [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)
#### Post date: [October 3, 2023, 3:34pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/36 "2023-10-03T15:34:00Z")
> [@Northern\_Piper](#):
>
> I’ll bet the answer is somewhere in the physics of inertialess mass that allows FTL travel without any pesky “jumps” or “wormholes”.
Yes, where is Bergenholm when we need him?
Or I’d settle for a spindizzy.
Who cares about those silly old-fashioned conservation laws, anyway?
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### Author:  [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)
#### Post date: [October 3, 2023, 5:31pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/37 "2023-10-03T17:31:16Z")
> [@Qadgop\_the\_Mercotan](#):
>
> It enabled us to fight ignorance and raise awareness about space operas and for me to pointlessly pontificate on precious pearls of prescience
And of course speculate upon the whichness of the why. Sir Austin Cardinge would understand, of course.
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### Author:  [@EdwardFound](https://boards.straightdope.com/u/EdwardFound)
#### Post date: [October 4, 2023, 5:12pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/38 "2023-10-04T17:12:31Z")
I suspect few, if any physicists ever thought that antimatter would behave differently to gravity. Antimatter is just matter, and there is nothing in General Relativity that distinguishes types of matter/energy. It’s just unfortunate that someone back in the day happened to choose the prefix “anti”, which gives lay folk (and SF writers) the impression that these particles are bizarro, opposite-matter.
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### Author:  [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)
#### Post date: [October 4, 2023, 5:33pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/39 "2023-10-04T17:33:35Z")
> [@EdwardFound](#):
>
> I suspect few, if any physicists ever thought that antimatter would behave differently to gravity.
Absolutely. Relativity has survived all the experimental and observational tests we have been able to do as far as I know.
Still, as Feynman said, “nature is what she is”; it is as well that we did the check.
And it’s I think still not _quite_ sure from the experimental data that the gravitational effect is exactly the same (though we all expect that’s just measurement uncertainty and will be resolved with better equipment).
But then towards the end of the 19th century physicists like Lord Kelvin were saying there is nothing much more to be done in physics: just add a few more decimal points to the measurements…
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### Author:  [@moes\_lotion](https://boards.straightdope.com/u/moes_lotion)
#### Post date: [October 4, 2023, 6:17pm UTC](https://boards.straightdope.com/t/how-does-gravity-react-with-anti-matter/778983/40 "2023-10-04T18:17:23Z")
> [@xtenkfarpl](#):
>
> And it’s I think still not _quite_ sure from the experimental data that the gravitational effect is exactly the same (though we all expect that’s just measurement uncertainty and will be resolved with better equipment).
This past weekend the CBC program “Quirks and Quarks” interviewed Timothy Friesen, one of the researchers involved in the CERN anti-hydrogen study.
[Antimatter falls down, much to the relief of physicists | Quirks and Quarks with Bob McDonald | Live Radio | CBC Listen](https://www.cbc.ca/listen/live-radio/1-51-quirks-and-quarks/clip/16012812-antimatter-falls-down-much-relief-physicists) (warning, autoplay at end of clip)
He noted that even though they did their best to cool the anti-hydrogen, the still present thermal motion and limited size of the test chamber meant that a portion of the atoms hit the top and sides. What they observed was that the expected percentage did hit the bottom of the chamber. To improve the accuracy they would need to start with a larger initial sample, suspended in a much larger chamber.
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