Praise be to Allah, and peace and blessings be upon the Messenger of Allah.
The Day of Judgment is one day, but it is a tremendous and very long day. Allah تعالى says:
“On a Day whose measure is fifty thousand years.” [Al-Ma'arij: 4]
And He says:
“And it will be a difficult day for the disbelievers.” [Al-Furqan: 26]
And He تعالى says:
“That Day will be a difficult day, not easy for the disbelievers.” [Al-Muddaththir: 9–10]
Thus, this long day will be extremely difficult for the disbelievers, while Allah will make it easy for the believers.
We should not delve deeply into how this duration will be experienced or try to measure it according to the conditions of this worldly life, because matters of the Hereafter belong to the unseen, and their reality differs from that of worldly matters. The Prophet ﷺ informed us that Allah has prepared for His righteous servants that which “no eye has seen, no ear has heard, and has never occurred to the heart of any human being.”
Just as the blessings of Paradise bear names that we know in this world—such as water, milk, honey, and fruit—yet their reality is not like that of worldly things, likewise the conditions of the Day of Judgment cannot be measured according to worldly conditions merely because some names or meanings are shared.
Therefore, the duty regarding matters of the unseen is to believe and submit, and not to delve into details that the Revelation has not explained. The Prophet ﷺ warned against excessive questioning and going to extremes, saying:
“Those who go to extremes are ruined.” Narrated by Muslim.
The Day of Judgment is one day, whose measure is fifty thousand years. It will be difficult for the disbelievers and easy for the believers. As for the nature of this duration and the true reality of the conditions of that day, they are matters of the unseen whose reality cannot be understood according to the measures of this world.
And Allah knows best.