The universe doesn't remember its infancy! Cosmologists searched for the echo of quantum gravity in the expansion rate of galaxies and found nothing. If it existed, dark energy would have a 'flavor' of the past. But for now, silence. So, the quantum nature of space-time must be caught by other means.
🎯 To directly detect quantum gravity, you'd need an accelerator the size of the Milky Way—that's why scientists look for its indirect traces.