Create accountLogin

Recent searches

No recent searches

Search options

Only available when logged in.
mathstodon.xyz is one of the many independent Mastodon servers you can use to participate in the fediverse.
A Mastodon instance for maths people. We have LaTeX rendering in the web interface!

Administered by:

Server stats:

2.8K
active users

mathstodon.xyz: AboutStatusProfiles directoryPrivacy policy

Mastodon: AboutGet the appKeyboard shortcutsView source codev4.3.7

#gravity

2 posts2 participants0 posts today
Public
Gravity Grinch

Fresh from the @j824h_arXiv_astro_ph : calculating (numerically) the impact of a wave hitting a spherical overdensity in the cosmos, the wave suffers from a Shapiro delay and thus shows interference patterns. So do we really need fuzzy dark matter to observe interference?! arxiv.org/abs/2504.08286

arXiv logo
arXiv.orgNumerical evolution of Maxwell's equations for wavefronts propagating through a spherical gravitational potentialWe present a scheme for numerically solving Maxwell's equations in a weakly perturbed spacetime without introducing the usual geometric optics approximation. Using this scheme, we study light propagation through a spherical perturbation of a stationary metric in the linear limit. Going beyond geometric approximation allows us to explore the wave optics effects that occur when the wavefront propagates through the gravitational potential. We find that the wavefront breaks on the gravitational potential due to the Shapiro time delay, i.e. due to the slowing down of light when propagating in an inhomogeneous spacetime. This again leads to constructive interference, resulting in a persistent frequency dependent amplification of parts of the wave amplitude. When the wave length is shorter than a certain threshold set by the induced gravitational mass, the waves are reflected on the curvature gradient.
#astronomy#GeneralRelativity#DarkMatter
Public
Mikko Tuomi

Back in 1915, Einstein put forth his most ambitious idea: the general theory of relativity, combining #gravity with #relativity to create an entirely new conception of our #Universe.

In most conventional circumstances, the predictions of Einstein’s theory are indistinguishable from that of its predecessor: Newton’s law of universal gravitation.

Is it possible, then, to somehow reduce Einstein’s equations down to Newton’s equations?

#physics
bigthink.com/starts-with-a-ban

Big ThinkAsk Ethan: Can we turn Einstein's equations into Newton's law?Einstein's General Relativity has reigned supreme as our theory of gravity for over a century. Could we reduce it back down to Newton's law?
Public
Dr. Miguel Montargès 🔭✨📡

Cette semaine, nous testions l'optique adaptative de l'instrument #GRAVITY+ de l'interféromètre du #VLT (#VLTI). Avant l'installation des étoiles laser sur les télescopes unitaires 1, 2 et 3, nous avons qualifié le système avec le télescope 4, équipé d'étoiles lasers depuis des années pour d'autres instruments.

J'étais au QG de l'@esoastronomy en Allemagne, mais Anthony Berdeu était sur place et a pu capturer la magie de la #Lune dans le désert d'#Atacama.

Lever de la Lune derrière l'ELT, le télescope européen géant de 39m de diamètre en construction sur le Cerro Armazones par l'ESO. La photo est prise par Anthony Berdeu depuis le VLT à 21km de distance.
Fin de l'éclipse totale de Lune du 14 mars 2025, avec un des lasers d'UT4 au premier plan. Crédits: Anthony Berdeu.
La fin de l'éclipse totale de Lune vue par Anthony Berdeu.
Coucher de Lune sur la mer de nuage au petit matin. L'ombre du Cerro Paranal qui héberge le VLT se projette sur l'atmosphère terrestre. Crédits: Anthony Berdeu.
SearchLive feeds
About