Time TravelEssay Preview: Time TravelReport this essayTime travelPresented to: Dr. Magd KahlPresented by : Sherif EhabMohamed El GarhyAbdel-Aziz selimKholoud tarekAstronomer Carl Sagan had it right when he said that time is “resistant to simple definition.” Lots of us think we know what time is, but it is hard to define. You can not literally see or touch time, but you can see its effects. The evidence that we are moving through time is found in everything — our bodies age, buildings weather and crumble, trees grow. Most of us feel the pressure of time as we are pushed to meet deadlines and make appointments. Our lives are often dictated by what time we need to be somewhere.
Today, I’d like to share a few of my books and blog posts about time travel. Today I’ll share a few of my other books and blog posts about time travel. I’ll bring some of the articles to light on a few topics that we’ve covered, I believe should be on any time travel agenda.I’ll begin with the best and most important ones:The reason I’m posting here is because all of the above have my name on them. I don’t read through a bunch of them all, but I think they each have some merit and some weaknesses, such as my poor spelling.I also am not an expert on most time travel topics. I love some time travel and some science and science books but if you get a bit ahead of yourself, you’re probably not going to like the idea of studying the universe or the sun. In a post on time travel, I’ll outline some of my best-loved science & science books (along with some of my favorite time travel novels), a lot of which have become my absolute favorites. I have my fair share of book reviews and articles (and I’m talking about the latter half of my two-hundredth year of life) but I’m sure many of you have been able to glean something new from reading my books (or perhaps an actual collection of books by some of my favorite authors).Some of the best books on my time travel projects:Some of the best times I’ve had (mostly with a friend)?And here is a post about some of the time traveled trips I’ve had.I don’t get a whole lot of requests for these books (I can’t really keep up with updates on some things), but I can say that I read the following posts many times:For those of you who haven’t read these books, there is an article you can read on space travel (link here). If you have been asked who I used as my time travel research, please check this out:What is Time Travel?Time travel is, at its core – and most importantly, how we connect time and space through the Universe and time travel at various scales. Let us look at the main issues first:The main problem with time travel is that it’s constantly changing in a weird way, usually with all of the changes happening in the same space. At times, this makes it difficult to use time wisely, or even keep track of which time zones are on that day to be on (there are also a lot of random trips on the Moon and Mars). The thing to remember when checking out a trip is to stay on time
Ask most people to define time and they are likely to look at their watch or a clock. We see time as the ticking of the hands on these devices. We know that there are 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day and 365 days in a year. These are the basic numbers of time that we all learned in grade school.
Time is also defined as being the fourth dimension of our universe. The other three dimensions are of space, including up-down, left-right and backward-forward. Time cannot exist without space, and likewise, space cannot exist without time. This interconnected relationship of time and space is called the spacetime continuum, which means that any event that occurs in the universe has to involve both space and time.
What is time travel? One standard definition is that of David Lewis’s: an object time travels iff the difference between its departure and arrival times in the surrounding world does not equal the duration of the journey undergone by the object. This definition applies to both natural and Wellsian time travel. For example, Jane might be a time traveler if she travels for one hour but arrives two hours later in the future (or two hours earlier in the past). In both types of time travel, the times experienced by a time traveler are different from the time undergone by their surrounding world.
But what do we mean by the “time” in time travel? And what do we mean by “travel” in time travel? As the definition for time travel presently stands, we need to clarify what we mean by the word “time” (see the next section). While philosophical analysis of time travel has attended mostly to the difficult issue of time, might there also be vagueness in the word “travel”? Our use of the word “travel” implies two places: an origin and a destination. “I’m going to Morocco,” means “I’m departing from my origination point here and I plan to arrive eventually in Morocco.” But when we are speaking of time travel, where exactly does a time traveler go? The time of origin is plain enough: the time of the time traveler and the time traveler’s surrounding world coincide at the beginning of the journey. But “where” does the time traveler arrive? Are we equivocating in our use of the word вЂ?travel’ by simply substituting a when for a where? In truth, how do we conceive of a “when”—as a place, a locale, or a region? Different scientific ontologies result in different ideas of what travel through time might be like. Also, different metaphysical concepts of time result in different ideas of what kinds of time travel are possible. It is to the issue of time in philosophy that we now turn
Einsteins theory of relativityBlack holes, according to relativity theory, warp spacetime with their enormously powerful gravitation field. The effect of this gravitational field is that if an astronaut were to cross the event horizon of a black hole, time would slow down on board his spacecraft as he approached the singularity and eventually come to a stop. Similarly time slows down in proportion to speed, the faster our astronaut travels the slower time runs. The closer the astronaut travels to the speed of light the more time slows, until at the speed of light, time would stop. Both these effects of time being affected by speed and gravity have been discussed in the previous section, all of which illustrates that time is not a fixed constant, but is affected by gravitational fields and relative speed in the same manner as the other three dimensions of space.
The solutions to particular equations of the Special Theory of Relativity can be expressed mathematically in any direction of time without running into any problems. Does this mean that time travel is possible? There is nothing in relativity that rules out time travel, it would appear to be theoretically possible.
Newtonian cosmologyNewton argued that space, time and motion were absolute, that is, that the entire universe was a single, uniform inertial frame and that time passed equably throughout it according to an eternally fixed, immutable and inexorable rate, without relation to anything external. Natural time travel in the Newtonian universe is impossible; there are no attributes or topography of space or time that can be exploited for natural time travel stories. Only time travel stories that exceed the bounds of Newtonian physics are possible and scenarios described by some Wellsian time travel stories (most notably like the one Wells himself wrote) are examples of such unscientific time travel.
Several philosophers and scientists objected to the notion of absolute space, time and motion, most notably Leibniz, Berkeley and Mach. Mach rejected Newtons implication that there was anything substantive about time: “It is utterly beyond our power to measure the changes of things by time. Quite the contrary, time is an abstraction, at which we arrive by means of the changes of things” (The Science of Mechanics, 1883). For Mach, change was more fundamental than the concept of time. We talk about time “passing” but what we’re really noticing is that things move and change around us. We find it convenient to talk as if there were some underlying flowing substance like the water of a river that carries these changes along with it. We abstract time to have a standard measuring tool by which we can quantify change. These views of Mach’s were influential for the young Albert Einstein. In 1905, Einstein