Whenever time travel is discussed, the idea of going back and manipulating history comes up. I've written a couple of books about the real science of time travel - How to Build a Time Machine ( Build Your Own Time Machine in the UK) and 10 Short Lessons in Time Travel . One of the main takeaways from these is that while time travel to the future is relatively easy thanks to the special theory of relativity, even without the paradoxes that inevitably arise, getting into the past is practically impossible, even though it is not strictly prohibited by the laws of physics. Yet I have discovered an interesting time travel related development involving manipulating the past.

Of course, changing our view of the past by re-writing history is nothing new. Arguably, everyone who writes a successful history book does this to some degree. And now that the internet is the major source of information for much of the world, comprehensively removing something from the net has become something of an industry for those who feel the need to manipulate history.

The other day, I was looking for a picture of a small monument, erected in Perth, Australia in 2005. It has always been of interest to me because it was specifically related to time travel. I've pulled up a picture of this structure several times in the past: my aim was to make sure that I had the exact wording on the metal plaque fixed to the monument. But when I searched online yesterday, I could find no reference to it. Its Wikipedia page has been deleted. Searching on Google for every possible combination of wording I could think of came up with nothing. Some might suspect men in  black were responsible, but I can only assume that the good people of Perth have decided that the existence of this monument made them a target of humour and so have expunged it from online history.

The reason the plaque is of interest to those writing about the science of time travel is that the it locates in time and space one of a few examples where attempts have been made to provide a destination point for travellers from the future. Other were a Baltimore, Maryland event held in 1982, hosted by a group called the Krononauts (they were taking it seriously, then), a time travellers' convention at MIT in 2005 and a time travellers' party thrown by Stephen Hawking that never had much hope of getting attendees given that it is both recorded as being in 2009 and 2012, may or may not have been at Gonville and Caius College in Cambridge, and Hawking was supposed to have provided 'precise GPS coordinates', but they are very difficult to find.

The Perth plaque was an altogether more solid concept. The monument described the location and time for 'Destination Day' where it as hoped time travellers would turn up. As I feel, for art's sake, that this time travel memento ought to be better preserved, here is the full text from the plaque:

In the event that the transportation of life from the future to the past is made possible this site has officially been designated as a landmark for the return of inhabitants of the future to the present day.

Destination Day

12 Noon (UTC/GMT + 8 hours)

31st March 2005

Forrest Place, Perth 6000, Western Australia

Latitude – Longitude

31.9522 – 115.8591

We welcome and await you

The question is, if they have expunged the Destination Day plaque from history because no one came (surely they would have left it there if time machines had turned up)... is its removal from easily accessible record why no one came?

See all of Brian's online articles or subscribe to a weekly digest for free here