Asslamo Allaikum Wa Rahmatullahi Wa Baraktuh,
Shaykh (Maulana) Qasim Nanotwi (RA) & Shaykh (Maulana) Ahmed Raza Khan Barelwee (RA) both lived in the time of Newtonian Physics i.e. before Einstein came and revolutionised our understanding of the universe with Quantum Physics and especially with his theory of relativity. It is critical to understand their era before we can understand what I am about to discuss.
The understanding of their time was that there was a direct relationship between cause and effect and universe was one-dimensional.
When Shaykh (Maulana) Qasim Nanotwi (RA) wrote Tahdhir al-Nas the subject matter was at least 75 years ahead of its time and it speaks volumes about the Eemaan of the man who evaluated the matter on the strength of the evidence (Hadeeth) and put aside the science of his time although we know that Shaykh (Maulana) Qasim Nanotwi (RA) knew about the scientific theories of his time and was particularly familiar with Mathematics as evident in his various biographies.
The works of later Deobandi Ulamah like Shaykh (Maulana) Ashraf Ali Thanwi (RA) in Bawadirun-Nawadir and even later ones like Shaykh (Mufti) Rasheed Ahmed Ludhyanwi (RA) in Ahsanul-Fatawa show that they had more than adequate knowledge of sciences.
Other Ulamah of the time such as Allamah 'Abd al-Hayy al-Lakhnawi (RA) defended Shaykh (Maulana) Qasim Nanotwi (RA) based on the strength of evidence (of Hadeeth) no matter how farfetched the idea sounded!
Einstein revolutionised our understanding of physics and we can now postulate that:
1. Universe is multidimensional and can have multiple realities: See the excellent article on Deoband.org
2. Time is not constant: If you put take two twins and leave one on Earth and send the other one to space travelling nearly at the speed of light and they meet each other 30 years later, the space twin will be much younger then the Earth
So when we read about the stories of Awliya of Allah (SWT) travelling at super fast speeds, becoming invisible or able to enter realms like the one described here science today accepts the possibility of all of these (at least theoretically, although not able to demonstrate it practically).
As a Muslim we believe in the Powers of Allah (SWT) and recognise him as the Creator and in Control over all things. Allah (SWT) created time, space and everything else and can change/manipulate them for his Awliya (friends) as He (SWT) pleases.
Spacetime continuum is a creation of Allah (SWT) and under the command of Allah (SWT) like anything else and it can bend enabling whosoever Allah (SWT) permits to travel faster then we can imagine and we have two authentic examples from the Qur’aan & Sunnah:
1. Asif Ibn Barkhiya (RA): The minister of Sayyidina Sulayman (AH) who claimed to be able to bring the throne of Bilqis instantaneously
2. Buraaq: The animal which carried the beloved of Allah (Sallallaho Alaihe Wassallam) on the night Journey of Mir’aaj from Makkah to Palestine to the seven heavens and back in next to no time!
Those with Eemaan before us accepted these matters on face value without having the scientific insight and we doubt it despite the science of our time confirming that all of these events are possible!
[2:117] (He is the) Originator of the heavens and the earth. When He decides a matter, He simply says to it: .Be! and it comes to be.