Dear all,

please find the minutes for today's call below. @Bishop: thanks a lot for leading today's discussion! @all: Let me know if you have any additions or comments to the minutes.

Btw, I still have problems to edit the wiki. Would you all agree to use a shared googledoc? I am asking because of the new EU data protection laws, which led KCL to warn us against using google. As long as we do not share any personal data, however, it should be fine.

cheers, Helvi

Call: Einstein Toolkit Working group ``Cosmology and Particles'', 25 June 2018

Participants: Katy Clough, Isabel Cordero, Michele Grasso, Bishop Mongwane, Daniele Vernieri, Helvi Witek

1) Reminder: EU Einstein Toolkit and school in Lisbon, September 2018 - Website: https://centra.tecnico.ulisboa.pt/network/grit/einsteintoolkit2018/ - Deadlines: 1 July 2018 (abstract submission); 15 July 2018 (registration)

2) Summer calls: - maybe have a call in July; NO call in August;. - next regular working group call: September 2018

3) Discussion: Bishop Mongwane on 3+1 formulation and hyperbolicity of f(R) theories - based on papers:. https://arxiv.org/abs/1610.07224 https://arxiv.org/abs/1707.05757

- motivation - f(R) gravity captures class of interesting cosmological models - e.g. Starobinsky model of inflation - under certain conditions equivalent to scalar-tensor theories ($f'(R) \sim \phi$) - achievements - derive time evolution formulation for f(R) gravity, specifically ADM and BSSNOK formulation - neat trick: use the 4-dimensional Ricci scalar $^{(4)}R$ and its time derivative $\psi=\p_{t} ^{(4)}R$ as independent variables - showed strong-hyperbolicity for BSSN-type formulation - numerical tests still problematic, maybe future work - Comments - BSSN only valid for $\det\tilde{\gamma}=1$; maybe reference metric formulation for spherically symmetric spacetimes - numerical issues related to gauge choice? - future numerical tests (a la ``apples with apples'') of non-trivial cosmological or black hole spacetimes - references for non-trivial or cosmological boundary conditions: - https://arxiv.org/abs/1409.3476 - https://arxiv.org/abs/1509.08354 - https://arxiv.org/abs/1204.2019 - general discussion on constraint evolution vs free evolution in future working group call (Isa)

=========================================== Dr. Helvi Witek Royal Society University Research Fellow Theoretical Particle Physics and Cosmology Department of Physics King's College London ===========================================

On Mon, Jun 25, 2018 at 3:22 PM, Bishop Mongwane astrobish@gmail.com wrote:

Hi all,

I'll be talking mostly from these 2 papers:

-> https://arxiv.org/abs/1610.07224 https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Farxiv.org%2Fabs%2F1610.07224&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=w55IrYoihCipghj7TpYUl4RtGZf%2FPPulnFqVDHdfj0I%3D&reserved=0 -> https://arxiv.org/abs/1707.05757 https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Farxiv.org%2Fabs%2F1707.05757&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=F8uJt%2F3%2F%2BK%2BmkqfgCHB2UCjScYWo4Rt%2BvuqQuhLYNYY%3D&reserved=0

See you in a moment.

Cheers, Bishop

On Mon, Jun 25, 2018 at 11:31 AM, helvi witek helvi.witek@kcl.ac.uk wrote:

...

Dear all,

this is a reminder for today's call at 4:30pm (BST, i.e. UK/Portugal) / 5:30pm (CDT). You can attend the meeting via the google hangout: https://hangouts.google.com/hangouts/_/tce4j4gzcfcormnadoauiqcvg4e https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhangouts.google.com%2Fhangouts%2F_%2Ftce4j4gzcfcormnadoauiqcvg4e&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=i54YG1gRzkngvduxiPLF8EYoCH9ZWB9a00avOEgYW0Y%3D&reserved=0

Bishop Mongwane will discuss his work on "3+1 formulation of and hyperbolicity in $f(R)$ theories".

If you have any further suggestions for topics to be discussed in the meeting, please add them to the meeting agenda: https://docs.einsteintoolkit.org/et-docs/Cosmology_and_Particles https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.einsteintoolkit.org%2Fet-docs%2FCosmology_and_Particles&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=DJ8U9lYk6TzqAjjb9ZTrVBfQm9f%2FugX40dx1yPBvBMQ%3D&reserved=0 or reply to this email if you also have difficulties to edit the wiki.

Best wishes, Helvi

=========================================== Dr. Helvi Witek Royal Society University Research Fellow Theoretical Particle Physics and Cosmology Department of Physics King's College London ===========================================

On Mon, Jun 18, 2018 at 6:32 PM, helvi witek helvi.witek@kcl.ac.uk wrote:

...

Dear all,

please consider joining our working group call next Monday, 25 June 2018, at 4:30pm (BST, i.e. UK/Portugal) / 5:30pm (CDT). You can attend the meeting via the google hangout: https://hangouts.google.com/hangouts/_/tce4j4gzcfcormnadoauiqcvg4e https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhangouts.google.com%2Fhangouts%2F_%2Ftce4j4gzcfcormnadoauiqcvg4e&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=i54YG1gRzkngvduxiPLF8EYoCH9ZWB9a00avOEgYW0Y%3D&reserved=0

Bishop Mongwane will discuss his work on "3+1 formulation of and hyperbolicity in $f(R)$ theories".

If you have any further suggestions for topics to be discussed in the meeting, please add them to the meeting agenda: https://docs.einsteintoolkit.org/et-docs/Cosmology_and_Particles https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.einsteintoolkit.org%2Fet-docs%2FCosmology_and_Particles&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=DJ8U9lYk6TzqAjjb9ZTrVBfQm9f%2FugX40dx1yPBvBMQ%3D&reserved=0 or reply to this email if you also have difficulties to edit the wiki.

cheers, Helvi =========================================== Dr. Helvi Witek Royal Society University Research Fellow Theoretical Particle Physics and Cosmology Department of Physics King's College London ===========================================

---

Cosmoparticle-wg mailing list Cosmoparticle-wg@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/cosmoparticle-wg https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.einsteintoolkit.org%2Fmailman%2Flistinfo%2Fcosmoparticle-wg&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=goyNp6Fu6%2FhoLHKH8JWCgoypaCY%2F8t4DYf4lBQNLD34%3D&reserved=0

--

.. with two they covered their face, with two they covered their feet, with two they did fly and one cried unto the other `Masina, masina, masina'

Yes, and we've been working on it.

Let me recap the issues:

The existing captcha stopped working for reasons beyond our control.

New solutions require an upgrade of the OS, PHP, etc.

Unfortunately, that breaks other components, e.g. ldap login. The ETK wiki shares a database with multiple groups at CCT.

The sysadmins have been looking for some solutions to get things back to a working state. They tell me they think they're close to an answer.

--Steve

On 06/25/2018 09:55 PM, Boud Roukema wrote:

hi all

On Mon, 25 Jun 2018, helvi witek wrote:

...

please find the minutes for today's call below. @Bishop: thanks a lot for leading today's discussion! @all: Let me know if you have any additions or comments to the minutes.

Thanks for the minutes. :)

...

Btw, I still have problems to edit the wiki. Would you all agree to use a shared googledoc? I am asking because of the new EU data protection laws, which led KCL to warn us against using google. As long as we do not share any personal data, however, it should be fine.

Isn't the ET community small enough to find out who the docs.einsteintoolkit.org sysadmins are and ask them to solve the bug after providing appropriate (https://www.chiark.greenend.org.uk/~sgtatham/bugs.html) diagnostic info? I'm new to the ET community so I don't know who is who that well... Rhaas made several edits to the wiki today.

Independently of the context of the EU GDPR, it would make more sense to trust responsibility for managing private data such as our IP numbers, browser versions, language preferences, at the level of Einstein Toolkit volunteers (einsteintoolkit.org geeks) rather than to a massive corporation. Managing a mediawiki server with an average of 30 edits per month https://docs.einsteintoolkit.org/et-docs/index.php?title=Special:Recentchang... should be easy compared to managing the full ET system.

By the way, the first issue of the inhomogeneous cosmology newsletter is available here:

https://cosmo.torun.pl/pipermail/inhom/2018-June/000000.html

Follow the link at the bottom ("More information ...") for subscribing (or unsubscribing).

Cheers Boud _______________________________________________ Cosmoparticle-wg mailing list Cosmoparticle-wg@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/cosmoparticle-wg

Thanks Helvi, and thanks Bishop, it was a very interesting talk.

@Helvi - I’m happy to use a shared googledoc, I always favour whatever is quickest to set up, and gets me back to doing research :-) Google knows what I have for breakfast.

Katy

On 25 Jun 2018, at 20:09, helvi witek helvi.witek@kcl.ac.uk wrote:

Dear all,

please find the minutes for today's call below. @Bishop: thanks a lot for leading today's discussion! @all: Let me know if you have any additions or comments to the minutes.

Btw, I still have problems to edit the wiki. Would you all agree to use a shared googledoc? I am asking because of the new EU data protection laws, which led KCL to warn us against using google. As long as we do not share any personal data, however, it should be fine.

cheers, Helvi

Call: Einstein Toolkit Working group ``Cosmology and Particles'', 25 June 2018

Participants: Katy Clough, Isabel Cordero, Michele Grasso, Bishop Mongwane, Daniele Vernieri, Helvi Witek

1. Reminder: EU Einstein Toolkit and school in Lisbon, September 2018

   • Website: https://centra.tecnico.ulisboa.pt/network/grit/einsteintoolkit2018/ https://centra.tecnico.ulisboa.pt/network/grit/einsteintoolkit2018/
   • Deadlines: 1 July 2018 (abstract submission); 15 July 2018 (registration)

2. Summer calls:

   • maybe have a call in July; NO call in August;.
   • next regular working group call: September 2018

3. Discussion: Bishop Mongwane on 3+1 formulation and hyperbolicity of f(R) theories

   • based on papers:. https://arxiv.org/abs/1610.07224 https://arxiv.org/abs/1610.07224 https://arxiv.org/abs/1707.05757 https://arxiv.org/abs/1707.05757

   • motivation

     • f(R) gravity captures class of interesting cosmological models
     • e.g. Starobinsky model of inflation
     • under certain conditions equivalent to scalar-tensor theories ($f'(R) \sim \phi$)

   • achievements

     • derive time evolution formulation for f(R) gravity, specifically ADM and BSSNOK formulation
     • neat trick: use the 4-dimensional Ricci scalar $^{(4)}R$ and its time derivative $\psi=\p_{t} ^{(4)}R$ as independent variables
     • showed strong-hyperbolicity for BSSN-type formulation

   • numerical tests still problematic, maybe future work

   • Comments

     • BSSN only valid for $\det\tilde{\gamma}=1$; maybe reference metric formulation for spherically symmetric spacetimes
     • numerical issues related to gauge choice?
     • future numerical tests (a la ``apples with apples'') of non-trivial cosmological or black hole spacetimes
     • references for non-trivial or cosmological boundary conditions: - https://arxiv.org/abs/1409.3476 https://arxiv.org/abs/1409.3476 - https://arxiv.org/abs/1509.08354 https://arxiv.org/abs/1509.08354 - https://arxiv.org/abs/1204.2019 https://arxiv.org/abs/1204.2019
     • general discussion on constraint evolution vs free evolution in future working group call (Isa)

=========================================== Dr. Helvi Witek Royal Society University Research Fellow Theoretical Particle Physics and Cosmology Department of Physics King's College London ===========================================

On Mon, Jun 25, 2018 at 3:22 PM, Bishop Mongwane <astrobish@gmail.com mailto:astrobish@gmail.com> wrote: Hi all,

I'll be talking mostly from these 2 papers:

-> https://arxiv.org/abs/1610.07224 https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Farxiv.org%2Fabs%2F1610.07224&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=w55IrYoihCipghj7TpYUl4RtGZf%2FPPulnFqVDHdfj0I%3D&reserved=0 -> https://arxiv.org/abs/1707.05757 https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Farxiv.org%2Fabs%2F1707.05757&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=F8uJt%2F3%2F%2BK%2BmkqfgCHB2UCjScYWo4Rt%2BvuqQuhLYNYY%3D&reserved=0

See you in a moment.

Cheers, Bishop

On Mon, Jun 25, 2018 at 11:31 AM, helvi witek <helvi.witek@kcl.ac.uk mailto:helvi.witek@kcl.ac.uk> wrote: Dear all,

this is a reminder for today's call at 4:30pm (BST, i.e. UK/Portugal) / 5:30pm (CDT). You can attend the meeting via the google hangout: https://hangouts.google.com/hangouts/_/tce4j4gzcfcormnadoauiqcvg4e https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhangouts.google.com%2Fhangouts%2F_%2Ftce4j4gzcfcormnadoauiqcvg4e&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=i54YG1gRzkngvduxiPLF8EYoCH9ZWB9a00avOEgYW0Y%3D&reserved=0

Bishop Mongwane will discuss his work on "3+1 formulation of and hyperbolicity in $f(R)$ theories".

If you have any further suggestions for topics to be discussed in the meeting, please add them to the meeting agenda: https://docs.einsteintoolkit.org/et-docs/Cosmology_and_Particles https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.einsteintoolkit.org%2Fet-docs%2FCosmology_and_Particles&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=DJ8U9lYk6TzqAjjb9ZTrVBfQm9f%2FugX40dx1yPBvBMQ%3D&reserved=0or reply to this email if you also have difficulties to edit the wiki.

Best wishes, Helvi

=========================================== Dr. Helvi Witek Royal Society University Research Fellow Theoretical Particle Physics and Cosmology Department of Physics King's College London ===========================================

On Mon, Jun 18, 2018 at 6:32 PM, helvi witek <helvi.witek@kcl.ac.uk mailto:helvi.witek@kcl.ac.uk> wrote: Dear all,

please consider joining our working group call next Monday, 25 June 2018, at 4:30pm (BST, i.e. UK/Portugal) / 5:30pm (CDT). You can attend the meeting via the google hangout: https://hangouts.google.com/hangouts/_/tce4j4gzcfcormnadoauiqcvg4e https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhangouts.google.com%2Fhangouts%2F_%2Ftce4j4gzcfcormnadoauiqcvg4e&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=i54YG1gRzkngvduxiPLF8EYoCH9ZWB9a00avOEgYW0Y%3D&reserved=0

Bishop Mongwane will discuss his work on "3+1 formulation of and hyperbolicity in $f(R)$ theories".

If you have any further suggestions for topics to be discussed in the meeting, please add them to the meeting agenda: https://docs.einsteintoolkit.org/et-docs/Cosmology_and_Particles https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.einsteintoolkit.org%2Fet-docs%2FCosmology_and_Particles&data=01%7C01%7Chelvi.witek%40kcl.ac.uk%7Cdc1f5f0064244e9904a808d5daaf68a0%7C8370cf1416f34c16b83c724071654356%7C0&sdata=DJ8U9lYk6TzqAjjb9ZTrVBfQm9f%2FugX40dx1yPBvBMQ%3D&reserved=0 or reply to this email if you also have difficulties to edit the wiki.

cheers, Helvi =========================================== Dr. Helvi Witek Royal Society University Research Fellow Theoretical Particle Physics and Cosmology Department of Physics King's College London ===========================================

---

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--

.. with two they covered their face, with two they covered their feet, with two they did fly and one cried unto the other `Masina, masina, masina'

---

Cosmoparticle-wg mailing list Cosmoparticle-wg@einsteintoolkit.org http://lists.einsteintoolkit.org/mailman/listinfo/cosmoparticle-wg