good evening i'm a van stopped for science for the public and i welcome you to tonight's contemporary science issues and innovations program our topic is time travel and our guest is david toomey professor of english at u mass amherst co director also of the english departments professional writing and technical communication program dr tunis teaching and work reflect a very broad background in expertise which several areas of literature plus science and technical writing the scope may help to explain his particular gift for translating exciting but difficult concepts in physics cosmology and astrobiology he's the acclaimed author of a number of popular science books tonight's discussion based on his two thousand and seven book the new time travelers a journey to the front years of physics was among ten nonfiction books named new and notable by scientific american in two thousand and seven and listed among the best site books two thousand and seven by library journal his two thousand physics world book of the year for two thousand and thirteen and named an editor's choice by the new york times sunday book review tonight dr toomey will explain why time travel is so alluring not just for science fiction and he'll tell us about the major contributions to the development of the idea he'll also talk about the significance of science fiction in the evolution of the idea of time travel it's a great pleasure to welcome by google hangouts from amherst massachusetts david to me dr to me welcome thank you and i'll start off since we're going to talk about time travel that there is a lot of confusion around the concept of time a lot of of dispute what is it about time that is such a problem  i know what it is until you're not asked me to explain it and in fact it's still pretty difficult when in fact physicists today do not have a good definition of the word now right i get that idea that they don't seem to have a because one of the difficulties that is in physics it seems from here that it is isolated from a material context so it's hard to think of time without change and change has to happen in a material context and material environment has to be something so that is perhaps one of the the difficulties that in physics it's sometimes just treated as a navy separate entity but in any case could you give us a little background about the concepts that  from physics that are most significant to the idea of time travel sure are the most significant concepts or min special relativity and general two very special relativity special relativity presents a concept of time as part of space  the idea that time and space are inseparable this is just would call them space time you have to this seems counter intuitive to us we think of space as having three is that it's quite impossible to imagine a point in space that's not also a point in time runestones imagine if you can the room you woke up in this morning if you you really can't alternately try to imagine point in time that's not a point in space so for instance a minute before midnight on new year's eve last year you  might be able to imagine it at times square or wherever you happen to be at the time but i think you really won't be able to manage to mention it without also imagining point and space this at the same time you as it were space and time are inseparable but then it's just so difficult to imagine now travelling backwards say in time can you help us out with that how can you have twins one one hundred years when number one was when number one stays on earth when number two travels very far away from earth and back again and if he wanted to travel very very close to the speed of light it would take in the ten years time measured on earth that we took only an hour or half an hour or a minute so about is right this part is understood that in principle this this can happen but in fact we don't know of anything material that can travel at the beat of light that's that's a small problem but let's just say for the moment that we're going to travel forward or back there these mechanisms of machines the time machines and so forth that are supposed   start just introduce this to remind everybody that there have been many examples in science fiction certainly but also the great scenes out of the christmas carol where the a person can travel back and observe past events and but the person is observing the past events and in almost like the way we do with dreams or something you cannot interact you don't really reconstitute the event is that true and in chime travel in travelling back and i'm thinking of the grandfather can it's not difficult to visualize the past we're always doing no wrong not is because the speed of light of the very very past is finite so when you look at the moon you are seeing the moon as it was one  one quarter seconds right when you look at the sun you're seeing the sun as it was eight minutes ago high so if you went very far from earth say a one hundred light years from earth and you're not a sufficiently ok now do you think sickly enter the warm hole and are there any conditions on us physically if you do this kind of strange trip well yeah keep it open long enough for someone to go through it some calculations suggested it would take the energy of three quarters of the stars in the milky way galaxy over a year the energy out moving backward or forward in space time by what there is there are different kinds of constructions wormholes and i think there's another one of those particular cylinder in space and there are all sorts of things to get to there but they idea is that you physically move human beings from this point the present either backward or forward in time correct ok all right just to get that straight then the other is you interviewed a number of really interesting physicists people might really enjoy reading about them it's very interesting the different kinds of ideas that came up would you mentioned like two or three people that you consider major contributors to this idea i  and that's interesting because thorne kip thorne has been so important in the idea as you as you mentioned of the gravitational waves and there's for a long time there were people that had doubts about that too and then the i guess general relatively relativity did predict such things but there was no way to prove it and then very recently we it was just a tremendous accomplishment so maybe this will come true in time as well but he has tremendous imagination in addition to the brilliance there are other things and you address this in the book that there was a the types of time travel discussed are pretty logical consequences of special relativity and in general relativity but to to divert to create along those lines but that's not so familiar i think in general and it's interesting how much these new geometries have contributed to not just this concept but a number of other concepts i'd like to turn now to your writing your own background which is kind of unusual you started out in literature is that correct  and why did i think you were a faulkner specialist is that true or was that did i make that up i mean i did study barker graduate school ok so there you were reading william faulkner and you got interested in science is it where you were always interested in science do you have a background in that also i was interested in science  antagonism in the liberal arts toward the senses and in fact there's there are many areas to be friendly about that there should be much more mutual interest i wonder if you think that there are literature background tribute to your writing abilities for these very difficult concepts like time travel not might not be writing yeah helps you be a better writer it's well what i mean is that some of these concepts are extremely abstract it's really quite difficult you have to spend a lot of time getting really acquainted with with the concepts and i'll point out that i'm not thinking just of this book but your other one weird life where the examination of this the the biochemistry it's a very difficult task and you took that one on also so you have and i wish you very very well in the future and thank you for writing these wonderful books for us good night