[et_pb_section fb_built=”1″ admin_label=”Section” _builder_version=”4.16″ _module_preset=”default” background_image=”https:\/\/www.ieec.cat\/wp-content\/uploads\/2022\/02\/slider-comunicacio.jpg” max_height=”130px” custom_padding=”0px||0px||false|false” da_disable_devices=”off|off|off” global_colors_info=”{}” da_is_popup=”off” da_exit_intent=”off” da_has_close=”on” da_alt_close=”off” da_dark_close=”off” da_not_modal=”on” da_is_singular=”off” da_with_loader=”off” da_has_shadow=”on”][\/et_pb_section][et_pb_section fb_built=”1″ admin_label=”Section” _builder_version=”4.16″ _module_preset=”default” custom_padding=”24px||11px|||” da_disable_devices=”off|off|off” global_colors_info=”{}” da_is_popup=”off” da_exit_intent=”off” da_has_close=”on” da_alt_close=”off” da_dark_close=”off” da_not_modal=”on” da_is_singular=”off” da_with_loader=”off” da_has_shadow=”on”][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_padding=”||||false|false” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Unitats de recerca” module_class=”ieec-orgs” _builder_version=”4.27.4″ _dynamic_attributes=”content” _module_preset=”default” text_font=”|700||on|||||” text_font_size=”16px” header_font=”|700|||||||” custom_margin=”||10px||false|false” header_font_size_tablet=”28px” header_font_size_phone=”26px” header_font_size_last_edited=”on|phone” global_colors_info=”{}”]@ET-DC@eyJkeW5hbWljIjp0cnVlLCJjb250ZW50IjoiY3VzdG9tX21ldGFfb3JnYW5pemFjaW9uZXMiLCJzZXR0aW5ncyI6eyJiZWZvcmUiOiIiLCJhZnRlciI6IiIsImVuYWJsZV9odG1sIjoib2ZmIn19@[\/et_pb_text][et_pb_post_title author=”off” categories=”off” comments=”off” featured_image=”off” admin_label=”T\u00edtol i data” module_class=”ieec-title” _builder_version=”4.27.4″ _module_preset=”default” title_font=”Cairo|300|||||||” title_font_size=”40px” meta_font=”||on||||||” meta_font_size=”16px” title_font_size_tablet=”35px” title_font_size_phone=”30px” title_font_size_last_edited=”on|desktop” global_colors_info=”{}”][\/et_pb_post_title][et_pb_text admin_label=”Subt\u00edtols” module_class=”ieec-summary” _builder_version=”4.27.4″ _module_preset=”default” text_font=”Source Sans Pro||on||||||” text_font_size=”24px” text_line_height=”1.1em” hover_enabled=”0″ text_font_size_tablet=”22px” text_font_size_phone=”20px” text_font_size_last_edited=”on|phone” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=”1_2,1_2″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”1_2″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_post_title title=”off” meta=”off” module_class=”ieec-img-container” _builder_version=”4.27.2″ _module_preset=”default” custom_margin=”||0px||false|false” border_width_top=”10px” border_color_top=”#406fda” global_colors_info=”{}”][\/et_pb_post_title][et_pb_text module_class=”ieec-img-footer” _builder_version=”4.27.4″ _module_preset=”default” text_font=”||||||||” text_font_size=”15px” text_line_height=”1.1em” background_color=”rgba(64,111,218,0.15)” custom_margin=”0px||||false|false” custom_padding=”30px|20px|30px|20px|true|true” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n
The MAGIC telescopes detect very high-energy gamma rays. MAGIC Consortium<\/strong><\/p>\n [\/et_pb_text][\/et_pb_column][et_pb_column type=”1_2″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n One of the challenges of modern physics is to successfully combine the theories of general relativity and quantum mechanics. As a result of these efforts, <\/span>several leading quantum gravity theories predict that the speed of light depends on the energy of its particles, the photons<\/b>.\u00a0<\/span><\/p>\n The <\/span>Institute of Space Studies of Catalonia<\/span><\/a> (IEEC \u2014 Institut d\u2019Estudis Espacials de Catalunya) and the <\/span>Universitat Aut\u00f2noma de Barcelona<\/span><\/a> (UAB), with researchers at UAB\u2019s Centre for Space Studies and Research (CERES), have collaborated with the <\/span>University of Aveiro<\/span><\/a> and the <\/span>University of Algarve<\/span><\/a> (both in Portugal) to look for this dependence based on the analysis of astrophysical observations of very energetic light from gamma-ray emissions from very distant sources. With unprecedented accuracy, the research shows that <\/span>the speed of light remains a universal constant<\/b>.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” hover_enabled=”0″ locked=”off” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n Determining the speed of light accurately is a problem with a long history. In 1887 one of the most important experiments in this regard took place. American scientists Michelson and Morley failed to measure the speed of the Earth by comparing the speed of light in the direction of the Earth’s motion with that perpendicular to it. <\/span>The speed was exactly the same in every direction<\/b>, regardless of our planet’s motion.\u00a0<\/span><\/p>\n That arguably most important \u2018zero measurement\u2019 in the history of science led Einstein to postulate that the speed of light is constant and consequently to formulate his theory of special relativity. This theory implies that <\/span>all laws of physics are the same, independent of the relative motion between observers<\/b>\u2014a concept known as Lorentz invariance.<\/span><\/p>\n Meanwhile, quantum theory was developed, with Lorentz invariance at the heart of all its theoretical frameworks, in particular quantum field theory and the Standard Model of Particle Physics. The latter is the most precisely tested theory ever developed and has been verified to incredible precision.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text module_class=”section-title” _builder_version=”4.27.4″ _module_preset=”default” header_2_font=”|700|||||||” header_2_font_size=”25px” hover_enabled=”0″ header_2_font_size_tablet=”23px” header_2_font_size_phone=”23px” header_2_font_size_last_edited=”on|phone” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” hover_enabled=”0″ locked=”off” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n So why doubt Lorentz invariance after 115 years of uninterrupted success? The answer once again starts with Albert Einstein\u2014this time with his theory of general relativity, which describes gravity as a deformation of geometry of spacetime<\/strong>. This theory has also proven to be extremely successful, having been tested to great precision in many circumstances ranging from weak to very strong gravity.<\/span><\/p>\n The problem lies in the fundamental incompatibility between the probability wave functions of quantum field theory\u2014the mathematical entities that describe quantum systems\u2014with their movement through curved geometry and at the same time their modifications of spacetime curvature. Most attempts to reconcile the two theories\u2014general relativity and quantum mechanics\u2014into a common framework of quantum gravity have resulted in the need to <\/span>break Lorentz invariance and consider that the speed of light is not constant<\/b>, albeit only slightly. Thus, Michelson and Morley\u2019s quest continues today.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text module_class=”section-title” _builder_version=”4.27.4″ _module_preset=”default” header_2_font=”|700|||||||” header_2_font_size=”25px” hover_enabled=”0″ header_2_font_size_tablet=”23px” header_2_font_size_phone=”23px” header_2_font_size_last_edited=”on|phone” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” hover_enabled=”0″ locked=”off” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n A team of researchers led by Merc\u00e8 Guerrero, former UAB student currently at University of Aveiro, and Anna Campoy-Ordaz, IEEC PhD student at the Department of Physics of the UAB, with the participation of Robertus Potting from the University of Algarve and Markus Gaug, associate professor at the Department of Physics of the UAB and also member of the IEEC, <\/span>has now tested Lorentz invariance,<\/b> that is to say, the constancy of the speed of light,<\/span> to unprecedented precision with the help of astrophysics. The results are published in the journal Physical Review D.<\/span><\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” text_text_color=”#FFFFFF” text_font_size=”21px” text_line_height=”1.1em” background_color=”#406fda” text_orientation=”center” width=”70%” width_tablet=”70%” width_phone=”70%” width_last_edited=”on|desktop” module_alignment=”center” custom_padding=”40px|50px|40px|50px|true|true” custom_padding_tablet=”40px|50px|40px|50px|true|true” custom_padding_phone=”30px|20px|30px|20px|true|true” custom_padding_last_edited=”on|phone” hover_enabled=”0″ text_font_size_tablet=”21px” text_font_size_phone=”19px” text_font_size_last_edited=”on|desktop” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n \u201cTiny differences in the group velocity of photons may accumulate into measurable arrival-time delays on Earth if the photons were emitted simultaneously from a source located at a very large distance,\u201d explains Markus Gaug, IEEC researcher at the CERES group of the UAB.<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” hover_enabled=”0″ locked=”off” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n One prediction of several Lorentz-Invariance-Violating quantum gravity theories is a dependence of the speed of light on photon energy. Any deviation from a constant speed of light must be extremely small to remain compatible with current constraints, but <\/span>may become detectable at the very highest photon energies<\/b>, known as very-high-energy gamma rays.<\/span><\/p>\n \u201cThis is possible because tiny differences in the group velocity of photons may accumulate into measurable arrival-time delays on Earth if the photons were emitted simultaneously from a source located at a very large distance,\u201d explains Gaug, also affiliated to CERES.<\/span><\/p>\n \u201cWe combined a collection of existing bounds from astrophysical measurements of very-high-energy gamma rays using a new statistical method to test a series of Lorentz-invariance-violating parametres, currently favoured by theoreticians, of the Standard Model Extension (SME),\u201d details the CERES researcher Campoy Ordaz.<\/span><\/p>\n The researchers hoped to prove Einstein wrong but, like so many others before them, did not succeed. Nevertheless, the research has increased tenfold the precision limit in measuring the constancy of the speed of light<\/strong>.<\/span><\/p>\n In the meantime, the quest to experimentally test the predictions of quantum gravity theories continues, with next-generation instruments just around the corner, such as the <\/span>Cherenkov Telescope Array<\/span><\/a> Observatory\u2014a collaboration involving several research units of the IEEC\u2014, designed to greatly improve performance on the detection of very-high-energy gamma rays from distant sources.<\/span><\/p>\n <\/p>\n Press release prepared in collaboration with the Universitat Aut\u00f2noma de Barcelona (UAB).<\/em><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_margin=”30px||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”M\u00e9s informaci\u00f3” module_class=”ieec-sub-title” _builder_version=”4.27.4″ _module_preset=”default” text_font=”Cairo|700|||||||” text_text_color=”#406fda” text_font_size=”20px” custom_margin=”||10px||false|false” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n More information<\/p>\n [\/et_pb_text][et_pb_text module_class=”ieec-sub-text” _builder_version=”4.27.4″ _module_preset=”default” text_font_size=”16px” text_line_height=”1.1em” link_font=”|700|||on||||” custom_margin=”20px||||false|false” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n This research is presented in a paper entitled \u201c<\/span>Bounding anisotropic Lorentz invariance violation from measurements of the effective energy scale of quantum gravity<\/span><\/a>\u201d, by <\/span>Guerrero M., Campoy-Ordaz A., Potting R. and Gaug M.<\/span>, to appear in the journal Phys. Rev. D 112 (2025) 104002 in November 2025.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”Enlla\u00e7os” module_class=”ieec-sub-title” _builder_version=”4.27.4″ _module_preset=”default” text_font=”Cairo|700|||||||” text_text_color=”#406fda” text_font_size=”20px” custom_margin=”||10px||false|false” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n Links<\/p>\n [\/et_pb_text][et_pb_text module_class=”ieec-sub-text” _builder_version=”4.27.4″ _module_preset=”default” text_font_size=”16px” text_line_height=”1.1em” link_font=”|700|||on|||#1a1140|” link_text_color=”#1a1140″ link_line_height=”1.4em” custom_margin=”20px||||false|false” global_colors_info=”{}”]<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”Contactes” module_class=”ieec-sub-title” _builder_version=”4.27.4″ _module_preset=”default” text_font=”Cairo|700|||||||” text_text_color=”#406fda” text_font_size=”20px” custom_margin=”||10px||false|false” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n Contacts<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=”2_5,3_5″ admin_label=”Row” _builder_version=”4.16″ _module_preset=”default” custom_margin=”0px||||false|false” custom_padding=”0px||||false|false” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_column type=”2_5″ _builder_version=”4.16″ _module_preset=”default” custom_padding=”|||20px|false|false” border_width_left=”1px” border_color_left=”#406fda” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_text _builder_version=”4.16″ _module_preset=”default” text_font_size=”16px” text_line_height=”1.1em” link_font=”|700|||on|||#1a1140|” link_text_color=”#1a1140″ link_line_height=”1.4em” header_4_font=”|700|||||||” header_4_text_color=”#1a1140″ custom_margin=”||||false|false” locked=”off” global_colors_info=”{}” theme_builder_area=”post_content”]<\/p>\n Castelldefels, Barcelona [\/et_pb_text][\/et_pb_column][et_pb_column type=”3_5″ _builder_version=”4.16″ _module_preset=”default” custom_padding=”|||20px|false|false” border_width_left=”1px” border_color_left=”#406fda” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” text_font_size=”16px” text_line_height=”1em” link_font=”|700|||on||||” link_text_color=”#1a1140″ header_4_font=”|700|||||||” header_4_text_color=”#1a1140″ hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″]<\/p>\n Institute of Space Studies of Catalonia (IEEC) Institute of Space Studies of Catalonia (IEEC) [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row module_id=”ieec-about” module_class=”about-ieec” _builder_version=”4.27.4″ _module_preset=”default” background_color=”rgba(64,111,218,0.15)” global_module=”17324″ global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” custom_padding=”20px|50px|20px|50px|true|true” global_colors_info=”{}”][et_pb_text admin_label=”Sobre l’IEEC” _builder_version=”4.16″ _module_preset=”default” header_2_font=”|700|||||||” header_2_font_size=”25px” custom_margin=”||10px||false|false” header_2_font_size_tablet=”23px” header_2_font_size_phone=”23px” header_2_font_size_last_edited=”on|phone” locked=”off” global_colors_info=”{}”]<\/p>\n [\/et_pb_text][et_pb_text admin_label=”Text” _builder_version=”4.16″ _module_preset=”default” text_font=”||on||||||” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n The Institute of Space Studies of Catalonia (IEEC \u2014 Institut d\u2019Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of more than 25 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centres, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC\u2019s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors.<\/p>\n The IEEC is a non-profit public sector foundation that was established in February 1996. It has a Board of Trustees composed of the Generalitat de Catalunya, Universitat de Barcelona (UB), Universitat Aut\u00f2noma de Barcelona (UAB), Universitat Polit\u00e8cnica de Catalunya \u00b7 BarcelonaTech (UPC), and the Spanish Research Council (CSIC). The IEEC is also a CERCA centre.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>\n","protected":false},"excerpt":{"rendered":" IEEC researchers at the Universitat Aut\u00f2noma de Barcelona (UAB) have collaborated with the University of Aveiro and the University of Algarve to search for a possible dependency of speed of light on the energy of its photons.<\/p>\n","protected":false},"author":5,"featured_media":41414,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"2880","footnotes":""},"categories":[110,111,74,98],"tags":[],"class_list":["post-41423","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-highlighted-news-big","category-highlighted-news-small","category-news","category-science"],"yoast_head":"\nThe constancy of the speed of light, in question<\/h2>\n
Gamma-rays to test Lorentz invariance<\/h2>\n
\n
IEEC Communication Office<\/h4>\n
E-mail: comunicacio@ieec.cat<\/a><\/p>\nLead Researcher at the IEEC<\/h4>\n
Anna Campoy Ordaz<\/h4>\n
Universitat Aut\u00f2noma de Barcelona (UAB)
E-mail: campoy@ieec.cat,<\/a> anna.campoy@uab.cat<\/a><\/p>\nMarkus Gaug<\/h4>\n
Universitat Aut\u00f2noma de Barcelona (UAB)
E-mail: gaug@ieec.cat,<\/a> markus.gaug@uab.cat<\/a><\/p>\nAbout the IEEC<\/h2>\n