NIAS Wednesday Discussion - Prof. Sisir Roy will speak on “Periodicity of redshift and new challenge to Big Bang”

NIAS Wednesday Discussion



Topic:              Periodicity of redshift and new challenge to Big Bang”                   


Speaker:          Sisir Roy

                        Senior Homi Bhabha Fellow and Visiting Professor, NIAS


Chairperson:   Dinesh Kumar Srivastava

                        Homi Bhabha Chair Professor, NIAS 



Date:               19 May 2021 


Time:               4.00 PM 


Meeting Link  Click here to join the meeting  


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Abstract: An approach for studying the large-scale structure of the universe lies in the detection and analysis of periodicity of redshift values of extragalactic objects, galaxies, and quasi-stellar objects (QSO), in particular. Studies of periodicity detection in redshift values of extragalactic objects, obtained from the Sloan Digital Sky Survey (SDSS), have been conducted in the past, largely based on the Fourier transform. Our study aims to revisit the same problem using the singular-value decomposition (SVD) as the primary tool. Periodicity detection and the determination of the fundamental period have been performed using a standard spectral approach as well as a SVD-based approach for a variety of simulated datasets. The analysis of the quasar redshift data from DR12 and galaxy redshift dataset of DR10 from SDSS data has been carried out. A wide range of periodicities have been observed in different redshift ranges of the quasar datasets. The analysis indicates the existence of periodicity, irrespective of the selection effect. The existence of periodicity for quasar and galaxy families clearly demands an alternative explanation of redshift, rather than Doppler-like mechanisms and poses a new challenge to the expanding model of the universe.  


About the speaker:  Sisir Roy is currently Senior Homi Bhabha Fellow and Visiting Professor, National Institute of Advanced Studies, Bengaluru. Formerly he was Professor, Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata.  



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For further info, please contact Prof Anindya Sinha [] or Shri K S Rama Krishna [], Coordinators of the NIAS Wednesday Discussion Meetings. 


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Wednesday, May 19, 2021