Forget technology. Just think in terms of metaphysical dynamics of other dimensions.
I've witnessed a dead person very briefly show up quite live- twice in fact over 20 years. The first time as my 83 year old grandmother. The second time I didn't quite recognize her as she looked around 30 years of age, which was 26 years before I was born. Yet somehow she looked familiar. I discovered an old photo of her a few weeks later.
Both unsolicited paranormal experiences were in broad daylight, and not the product of a hallucination. Though ever since, it did make me wonder how many "dead people" have walked right by me where neither one of us acknowledged the other.
Now if that doesn't constitute "time travel", I don't know what would. Of course whatever it involves, it is not of this plane of existence with its present limitations of known science. From this perspective, time travel has always been "normal". But only seen by a few of us. Nothing funnier than saying, "I see dead people" and hearing people laugh. Most have no idea...
At times I do wonder if in the course of reincarnation that we can chose the time we live in.