PUNE: Ten years ago at an international conference in Melbourne, renowned Indian theoretical physicist Thanu Padmanabhan from the Inter-University Centre for Astronomy and Astrophysics, threw a challenge to the international community of astrophysicists to prove his ideas on dark energy wrong by 2016.On Thursday, David Wiltshire made an announcement conceding the wager in the CosPa2016 International conference in Sydney. Dark energy makes up three quarters of the universe and is also an enigmatic topic of discussion among cosmologists and astro-enthusiasts.At the end of his plenary talk on December 15, 2006 at the 23rd Texas Symposium, Padmanabhan offered a bet to the audience that in the next ten years there will be no evidence to contradict the theory that dark energy (cosmological constant) is the root cause of accelerated expansion of the universe.The challenge was taken up by Wiltshire, professor in the department of physics and astronomy, University of Canterbury, New Zealand. “Mathematics shows that dark energy behaves like a fluid and it has negative pressure,” Padmanabhan told TOI.Before 2006, many models have tried to explain dark energy. Whereas Wiltshire, while accepting that a cosmological term may have relevance at some scale, was convinced that present epoch dark energy will in future be observationally shown to be an historical accident arising from our misinterpretation of gravitational energy, which is non-local.Four years ago, while working on a deeper paradigm of Einstein’s theory, Padmanabhan along with his daughter Hamsa Padmanabhan, co-authored a paper where they derived the numerical value of the cosmological constant.