Why the Past Cannot Be Changed
Posted on 2025/08/17
by Star Huang
Edited by Peng Xuankai
"Love is the one thing that we're capable of perceiving that transcends dimensions of time and space." — Dr. Brand, “Interstellar”
When Cooper is abandoned close to the black hole Gargantua by his Endurance crewmates, he's sentenced to death. General relativity had predicted that those tremendous tidal forces near a black hole singularity would spaghettify everything, being drawn out to infinity. But far from dying, Cooper finds himself inside a gigantic latticework structure — “a five-dimensional ‘tesseract’ built by humanity from the distant future.“
Time is no longer an inexorable arrow here. It's a physical world, where you can go, as if those moments in Murph's bedroom are a "place" on an endless shelf. And Cooper learns a brutal lesson — he can't return. What he can do is write messages that were always included in what had already occurred.
Why did Cooper go into the fifth dimension?
1. General relativity and singularities
Einstein's field equations:
They foretell infinite spacetime curvature in the singularity of the black hole. At such boundaries, physics fails. In the real world, absolutely no one has any idea what happens if you cross the event horizon. The film envisions a tech-savvy civilization that possesses technology to distort spacetime in that boundary and create a non-interacting high-dimensional structure in Gargantua.
2. Higher-dimensions Theories
String theories and brane-world scenarios advance that other dimensions than four may reside within our universe. With respect to the tesseract, "extra" dimensions would permit time to be traversed as topography. Time is linear and frozen to four-dimensional beings. Time is open and can potentially be traveled backwards and forwards by higher-dimensional beings.
3. A bridge rather than an empty space
Rather than dropping Cooper into a deadly singularity, then, the tesseract is a portal — not from some other place in space, but from all other places within the lifetime of one man. That is consistent with interior film logic: science has given open portals into time, but not control over time.
Why can't he change his past?
This follows from the Novikov self-consistency principle: if time travel is allowable, then everything is self-consistent. Whatever you do in the past must constitute part of history. Coop's Morse-code transmission to Murph does not "change" the past; it's how she'd always received with quantum information. She'd been reliant upon this moment from the start — his doing so couldn't have been avoided.
A Physics analogy:
Had you been changing the past at will, you'd run into paradoxes such as the grandfather paradox: not keeping your grandparents together would erase your own existence, so you'd not have been able to prevent them from getting together. But by making every event in the past self-consistent with what really did occur, self-consistency prevents paradoxes and maintains causality.
Physics Behind the fiction:
Though the tesseract does not exist, the film bases it in actual physical laws:
- Black holes are extreme laboratories for spacetime, where gravity distorts space and time so significantly that regular laws do not apply.
- Higher dimensions of Theoretical Physics — principally through string theory, there may be additional dimensions which would afford odd structures and connections.
- Time as a space-like dimension — Time in extra dimensions would be space-like and would allow for passage but would remain causally constrained.
- Causality preserving— Even for exotic cases, self-consistency maintains causality intact. This is how Interstellar employs high-concept concept not to skirt physics, but to push it into speculable extension.
From natural sciences to philosophy
The tesseract series educates us with an enduring limitation: whatever the dimensions may be, even into infinity, time's nature cannot be altered. Science will probably enable people to “move” anywhere in time, but not rewrite it. Cooper's passage through the tesseract isn't one of altering what was — it's one of making sure what was meant to be. His mission isn't the work of a time editor, but a messenger. What is done cannot be altered; the present is the realm of choice and change. This is a larger truth: human agency is not in undoing what's been done, but in deciding what comes next. Our lives, Murph's watch included, bear the history of past signals — embedded and fixed — but they dictate where they lead us next.
Closing thoughts
The fifth dimension of Interstellar is a fine blend of speculative physics and emotional closure. It borrows from general relativity, higher-dimensional thinking, and causality theories to come up with an atmosphere scientifically viable as well as necessary for the story. By allowing Cooper to see all of time but not alter it, the film accepts the restrictions of science and human capacity — and redefines them as a mandate to act in the here and now. Perhaps the best aphorism is not that love "transcends" time in the most absolute sense, but that communion and understanding remain in it. We do not get to efface the past, but because of it, we can live — and love — more richly. --- If you'd like, I can do that now in the actual cinematic + analytical tone of your work in your essays on Ad Astra and Tenet, such as splitting it into visually distinct thematic segments and the same paragraph rhythm. That would, of course, make it part of your ongoing series. Would you like me to do it next?
