Free Astronomy Magazine May-June 2024 ARABIC VERSION

17 hen you are trying to solve one of the biggest conundrumsincosmol- ogy, you should triple check your homework. The puzzle, called the “Hubble Tension,” is that the cur- rent rate of the expansion of the universe is faster than what as- tronomersexpectittobe,basedon theuniverse’sinitialconditionsand our present understanding of the universe’s evolution. Scientists using NASA’s Hubble SpaceTelescopeandmanyothertel- escopesconsistentlyfindanumber that does not match predictions based on observations from ESA’s (European Space Agency’s) Planck mission.Doesresolvingthisdiscrep- ancyrequirenewphysics?Orisita result of measurement errors be- tween the two different methods used to determine the rate of ex- pansion of space? Hubblehasbeenmeasuringthecur- rentrateoftheuniverse’sexpansion for30years,andastronomerswant to eliminate any lingering doubt aboutitsaccuracy.Now,Hubbleand NASA’sJamesWebbSpaceTelescope have tag-teamed to produce de- finitive measurements, furthering the case that something else – not measurementerrors–isinfluencing the expansion rate. “With measurement errors negated, whatremainsistherealandexciting possibility we have misunderstood the universe,” said Adam Riess, a physicist at Johns Hopkins University in Baltimore. Riess holds a Nobel Prizeforco-discoveringthefactthat theuniverse’sexpansionisaccelerat- ing, due to a mysterious phenome- non now called “dark energy.” Asacrosscheck,aninitialWebbob- servation in 2023 confirmed that Hubble measurements of the ex- panding universe were accurate. However,hopingtorelievetheHub- bleTension,somescientistsspecu- lated that unseen errors in the measurement may grow and be- comevisibleaswelookdeeperinto the universe. In particular, stellar crowding could affect brightness measurementsofmoredistantstars in a systematic way. The SH0ES (Supernova H0 for the Equation of State of Dark Energy) team, led by Riess, obtained addi- tional observations with Webb of objectsthatarecriticalcosmicmile- postmarkers,knownasCepheid variablestars,whichnowcanbe correlated with the Hubble data. “We’venowspannedthewhole rangeofwhatHubbleobserved, andwecanruleoutameasurement errorasthecauseoftheHubble Tensionwithveryhighconfidence,” Riess said. Theteam’sfirstfewWebbobserva- tions in 2023 were successful in showing Hubble was on the right track in firmly establishing the fi- delity of the first rungs of the so- called cosmic distance ladder. Astronomersusevariousmethodsto measure relative distances in the universe, depending upon the ob- ject being observed. Collectively these techniques are known as the cosmic distance ladder– eachrung MAY-JUNE2024 ﺗ ﻤــﻊ ﻫــﺬﻩ اﻟﺼــﻮرة ﻟﻤﺠــﺮة NGC 5468 ﺗﻘــﻊ ﻋﻠــﻰ ﻌــﺪ ﺣــﻮاﻟﻲ ، اﻟــ 130 ﻣﻠﻴــﻮنﺳــﻨﺔ ﺿــﻮﺋ ﺔ ﻣــﻦ ــﺐ اﻷرض، ﺑ ﺎﻧـﺎت ﻣـﻦ اﻟﺘﻠﺴـ ﻮ ﺎت اﻟﻔﻀـﺎﺋ ﺔ ﻫﺎﺑـﻞ وﺟـ ﻤﺲو . ﻫـﺬﻩ ﻫـﻲ أ ﻌــﺪ ﻣﺠـﺮة ﺣــﺪد ﻓﻴﻬـﺎ ﻫﺎﺑـﻞ ـــﺔ اﻟﻤﺘﻐـــ ة اﻟﻨﺠـــﻮم اﻟﻘ ﻔﺎو . ﻫــــﺬﻩ ﻋﻼﻣـــﺎتﻫﺎﻣـــﺔ ــــﻮن ــــﺎسﻣﻌـــﺪل ﺗﻮﺳـــﻊ اﻟ ﻟﻘ . ﺗـــﻢ رـــﻂ اﻟﻤﺴــــﺎﻓﺔ ــﺎت ﻣـﻊ ﻣﺴـﺘﻌﺮ أﻋﻈــﻢ ﻣــﻦ اﻟﻨـﻮع اﻟﻤﺤﺴـﻮ ﺔ ﻣــﻦ اﻟﻘ ﻔﺎو Ia ﻓــﻲ اﻟﻤﺠــﺮة . اﻟﻤﺴـﺘﻌﺮات اﻟﻌﻈﻤــﻰ ﻣــﻦ اﻟﻨـﻮع Ia ﺗﺘﺠــﺎوزﻧﻄــﺎق اﻟﻨﺠــﻮم ــﺔ اﻟــ ـﺎس اﻟﻤﺴـﺎﻓﺎت اﻟ ﻮﻧ ﺷــﺪ ﺪة اﻟﺴــﻄﻮع ﻟﺪرﺟــﺔ أﻧﻬــﺎ ﺗُﺴـﺘﺨﺪم ﻟﻘ إﻟﻰ ﺗﻮﺳﻴﻊ ﻗ ﺎﺳﺎت ﻣﻌﺪل ﺗﻮﺳﻊ اﻟ اﻟﻘ ﻔﺎو ﺔ، ﻣﻤﺎ ﻳﺆد ﻮن إﻟﻰﻋﻤﻖ اﻟﻔﻀﺎء . [NASA, ESA, CSA, STScI, AdamG. Riess (JHU, STScI)] ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ - ﻣﺎﻳﻮ ﻳﻮﻧﻴﻮ 2 0 2 4 17 ﻋﻨـﺪﻣﺎ ﺗﺤﺎول ﺣﻞ واﺣﺪة ﻣﻦ أﻛﱪ اﻷﻟﻐﺎز ﰲ ﻋﻠـﻢ اﻟﻜﻮﻧﻴـﺎت ﻳﺠـﺐ ﻋﻠﻴـﻚ اﻟﺘﺤﻘـﻖ ﻣــﻦ واﺟﺒﺎﺗﻚ ا ﻨﺰﻟﻴﺔ ﺛﻼث ﻣﺮات . اﻟﻠﻐـﺰ ا ﺴـﻤﻰ " ﺗﻮﺗﺮ ﻫﺎﺑﻞ " ﻫﻮ أن ا ﻌـﺪل اﻟﺤـﺎﱄ ﻟﺘﻮﺳـﻊ اﻟ ﻜﻮن أﴎع ﻣﻤﺎ ﻳﺘﻮﻗﻌﻪ ﻋﻠﻤﺎء اﻟﻔﻠـﻚ ﺑﻨـﺎءً ﻋﲆ اﻟﻈﺮوف اﻷوﻟﻴﺔ ﻟﻠﻜـﻮن وﻓﻬﻤﻨـﺎ اﻟﺤـﺎﱄ ﻟﺘﻄﻮر اﻟﻜﻮن . ﻳﺠﺪ اﻟﻌﻠﻤـﺎء اﻟـﺬﻳﻦ ﻳﺴـﺘﺨﺪﻣﻮن ﺗﻠﺴـﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟﺘـﺎﺑﻊ ﻟﻨﺎﺳـﺎ واﻟﻌﺪﻳـﺪ ﻣـﻦ اﻟﺘﻠﺴــﻜﻮﺑﺎت اﻷﺧــﺮى ﺑﺎﺳ ـﺘﻤﺮار رﻗﻤًــﺎ ﻻ ﻳﺘﻄﺎﺑﻖ ﻣﻊ اﻟﺘﻮﻗﻌﺎت ﺑﻨﺎءً ﻋﲆ ارﺻﺎد ﺑﻌﺜـﺔ ﺑﻼﻧﻚ اﻟﺘﺎﺑﻌﺔ ﻟﻮﻛﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑﻴﺔ . ﻫﻞ ﻳﺘﻄﻠﺐ ﺣﻞ ﻫﺬا اﻟﺘﻨﺎﻗﺾ ﻓﻴﺰﻳﺎء ﺟﺪﻳﺪة؟ أم أﻧﻪ ﻧﺘﻴﺠﺔ ﻷﺧﻄﺎء اﻟﻘﻴﺎس ﺑ اﻟﻄـﺮﻳﻘﺘ ا ﺨﺘﻠﻔ ﺘ ا ﺴﺘﺨﺪﻣﺘ ﻟﺘﺤﺪﻳﺪ ﻣﻌﺪل ﺗﻤـﺪد اﻟﻔﻀﺎء؟ ﻟﻘﺪ ﻇﻞ ﺗﻠﺴـﻜﻮب ﻫﺎﺑـﻞ اﻟﻔﻀـﺎﺋﻲ ﻳﻘـﻴﺲ ا ﻌﺪل اﻟﺤﺎﱄ ﻟﺘﻮﺳـﻊ اﻟﻜـﻮن ـﺪة 30 ﻋﺎﻣـﺎ وﻳﺮﻳﺪ ﻋﻠﻤﺎء اﻟﻔﻠﻚ إزاﻟﺔ أي ﺷﻚ ﻣﺘﺒﻘﻲ ﻟﺪﻳﻬﻢ . ﺣﻮل دﻗﺘﻪ اﻵن ﻳ ﺘﻌــﺎون ﺗﻠﺴــﻜﻮب ﻫﺎﺑــﻞ اﻟﻔﻀــﺎﺋﻲ وﺗﻠﺴﻜﻮب ﺟـﻴﻤﺲ وﻳـﺐ اﻟﻔﻀـﺎﺋﻲ ا ﻟﺘـﺎﺑﻊ ﻟﻨﺎﺳﺎ ﻹﻧﺘﺎج ﻗﻴﺎﺳﺎت ﻣﺤﺪدة ﻣ ﻤﺎ ﻳﻌﺰز ﻓﻜﺮة أن ﺷﻴﺌًﺎ آﺧﺮ - وﻟﻴﺲ أﺧﻄﺎء اﻟﻘﻴـﺎس - ﻫـﻮ اﻟﺬي ﻳﺆﺛﺮ ﻋﲆ ﻣﻌﺪل ﺗﻮﺳﻊ اﻟﻜﻮن . ﻗﺎل آدم رﻳﺲ ﻋﺎﻟﻢ اﻟﻔﻴﺰﻳﺎء ﰲ ﺟﺎﻣﻌﺔ ﺟـﻮﻧﺰ ﻫـﻮﺑﻜﻨﺰ ﰲ ﺑـﺎﻟﺘﻴﻤﻮر :» ﻣـﻊ ﻧﻔـﻲ أﺧﻄــﺎء اﻟﻘﻴﺎس ﻣﺎ ﻳﺘﺒﻘﻰ ﻫـﻮ اﻻﺣﺘﻤـﺎل اﻟﺤﻘﻴﻘـﻲ وا ﺜ ﺑﺄﻧﻨﺎ ﻗﺪ أﺳﺄﻧﺎ ﻓﻬﻢ اﻟﻜﻮن «. ﺣﺼﻞ رﻳﺲ ﻋﲆ ﺟـﺎﺋﺰة ﻧﻮﺑـﻞ ﺸـﺎرﻛ ﺘﻪ ﰲ اﻛﺘﺸﺎف ﺣﻘﻴﻘﺔ أن ﺗﻮﺳـﻊ اﻟﻜـﻮن ﻳﺘﺴـﺎرع ﺑﺴﺒﺐ ﺑﺴﺒﺐ ﻇﺎﻫﺮة ﻏﺎﻣ ﻀﺔ ﻏ ﻣﻔﻬﻮﻣﻪ ﺗﺴـﻤﻰ اﻵن " اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ." ﻛﻤ ﺎ ﻫﻮ ﻣﺘﻮﻗﻊ أﻛﺪت أرﺻﺎد ﺗﻠﺴﻜﻮب وﻳـﺐ اﻷوﻟﻴﺔ ﰲ ﻋﺎم 2023 أن ﻗﻴﺎﺳﺎت ﻫﺎﺑﻞ ﻟﻠﻜﻮن ا ﺘﻮﺳﻊ ﻛﺎﻧﺖ دﻗﻴﻘﺔ . ﻣﻊ ذﻟﻚ، وﻋﲆ أﻣﻞ ﺗﺨﻔﻴﻒ ﺗﻮﺗﺮ ﻫﺎﺑﻞ، ﺗﻜﻬﻦ ﺑﻌﺾ اﻟﻌﻠﻤﺎء ﺑـﺄن اﻷﺧﻄـﺎء ﻏـ ا ﺮﺋﻴـﺔ ﰲ اﻟﻘﻴﺎس ﻗﺪ ﺗﻨﻤﻮ وﺗﺼﺒﺢ ﻣﺮﺋﻴﺔ ﻋﻨﺪﻣﺎ ﻧﻨﻈـﺮ ﺑﺸﻜﻞ أﻋﻤﻖ إﱃ اﻟﻜﻮن وﻋﲆ وﺟﻪ اﻟﺨﺼﻮص ﻳﻤﻜﻦ أن ﻳ ﺆﺛﺮ اﻻزدﺣﺎم اﻟﻨﺠﻤﻲ ﻋﲆ ﻗﻴﺎﺳﺎت ﺳﻄﻮع اﻟﻨﺠﻮم اﻟﺒﻌﻴﺪة ﺑﻄﺮﻳﻘﺔ ﻣﻨﻬﺠﻴﺔ . ﺣﺼﻞ ﻓﺮﻳﻖ SH0ES ) ا ﺴـﺘﻌﺮ اﻷﻋﻈـﻢ H0 ﻌﺎدﻟﺔ ﺣﺎﻟﺔ اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ( ﺑﻘﻴـﺎدة رﻳـﺲ أرﺻﺎد ﻋﲆ إﺿﺎﻓﻴﺔ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮب وﻳﺐ ﻟﻸﺟﺴﺎم اﻟﺘﻲ ﺗ ﻌﺘﱪ ﻋﻼﻣﺎت ﻫﺎﻣـﺔ ﻟﻠﺘﻄـﻮر اﻟﻜﻮﻧﻲ وا ﻌﺮوﻓﺔ ﺑﺎﺳﻢ اﻟﻨﺠـﻮم اﻟﻘﻴﻔﺎوﻳـﺔ ا ﺘﻐ ة واﻟﺘـﻲ ﻳﻤﻜـﻦ اﻵن رﺑﻄﻬـﺎ ﺑﺒﻴﺎﻧـﺎت . ﻫﺎﺑﻞ ﻗﺎل رﻳﺲ " : ﻟﻘﺪ ﻗﻤﻨـﺎ اﻵن ﺑﺘﻐﻄﻴـﺔ اﻟﻨﻄـﺎق اﻟﻜﺎﻣﻞ ﺎ رﺻﺪه ﺗﻠﺴـﻜﻮب ﻫﺎﺑـﻞ اﻟﻔﻀـﺎﺋﻲ وﻳﻤﻜﻨﻨﺎ أن ﻧﺴﺘﺒﻌﺪ وﺟﻮد ﺧﻄـﺄ ﰲ اﻟﻘﻴـﺎ س ﻛﺴﺒﺐ ﻟﺘﻮﺗﺮ ﻫﺎﺑﻞ ﺑﺜﻘﺔ ﻋﺎﻟﻴﺔ ﺟﺪ ". اً ﻧﺠﺤﺖ ﻋﻤﻠﻴﺎت رﺻﺪ وﻳﺐ اﻟﻘﻠﻴﻠﺔ اﻷوﱃ اﻟﺘﻲ أﺟﺮاﻫﺎ اﻟﻔﺮﻳـﻖ ﰲ ﻋـﺎم 2023 ﰲ إﻇﻬـﺎر أن ﻫﺎﺑﻞ ﻛﺎن ﻋﲆ ا ﺴﺎر اﻟﺼﺤﻴﺢ ﰲ إﺛﺒﺎت دﻗـﺔ اﻟـﺪرﺟﺎت اﻷوﱃ ـﺎ ﻳﺴـﻤﻰ ﺑﺴـﻠﻢ ا ﺴـﺎﻓﺔ اﻟﻜﻮﻧﻴﺔ . ﻳﺴﺘﺨﺪم ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻃﺮﻗًﺎً ﻣﺨﺘﻠﻔﺔ ﻟﻘﻴـﺎس ا ﺴـﺎﻓﺎت اﻟﻨﺴـﺒﻴﺔ ﰲ اﻟﻜـﻮن اﻋﺘﻤـﺎد اً ﻋـﲆ اﻟﺠﺴﻢ اﻟﺬي ﻳﺘﻢ رﺻﺪه وﺗُﻌﺮف ﻫﺬه اﻟﺘﻘﻨﻴﺎت ﻣﺠﺘﻤﻌﺔ ﺑﺴﻠﻢ ا ﺴﺎﻓﺔ اﻟﻜﻮﻧﻴﺔ .