The definition of time has puzzled and perplexed many great minds, and no single, uniform definition exists, making the concept of time a great source of debate.
Isaac Newton defined time as a container, and along with space, all events occurred within that container. His beliefs were based around the concept of absolute time and space, meaning that time is moving at the same rate for everything in the universe, or can be scaled for everything in the universe.
Albert Einstein revised the theory of absolute time, and proposed the theory of special relativity, and then later revised this theory to form The General theory of Relativity. [Wikipedia article] In simple terms, this theory states that time is measured by motion. It states that time can be effected by things such as gravity, and the motion of objects. It also states that time is a fourth dimension, meaning that in our three dimensional world we cannot "see" time. The best way to visualize the concept of another dimension is to think about an apple sitting in a bowl. If someone asked you where it was, you could say how far forward the apple was, or how far to the left, but you could only describe where the apple is now, not where it will be tomorrow or the next day, because those measurements exist in a different dimension. This also implies that the past, present and future exist equally within that dimension.
This theory is the most widely accepted, and most new theories or ideas about time are based upon this theory.
Beginning of time
Time, according to the big bang theory, began 15(some sources say 10) billion years ago. Time began with the formation of the universe. This is explained by the fact that, before the big bang, all of the matter in what would be the universe was compressed into one unit (technical term: a singularity). For the sake of understanding this concept, you can think of it as a small box. (understand that it has no volume or any real measurements). This box has an infinite density. this means that all of the laws of physics cannot apply to this pre-universe box. Because scientific laws don't apply to this pre-universe box, anything that happened to this pre-universe box isn't measurable by the standards that apply to our universe. Therefore, it cannot be on the same time frame as our universe, because the laws of our universe do not apply to the pre-universe box. Time had to begin with the big bang.
Note- That was only a visualization to understand the concept. The matter of the universe was not literally compressed into anything remotely similar to a box.
There are other theories and ideas about the beginning of time (or the lack of a beginning), however I just explained the most common theory. Some theories deny that a singularity ever existed; thus making time infinite.
End of Time
Time as we know it can only exist within the confines of our universe, according to the big bang theory, which is why time began with the big bang. This would also imply that time could end with the end of the universe. One such explanation for this is known as the theory of Heat Death. This theory states that it's possible for the universe to reach a frozen state, in which energy is non existent to sustain motion or life. Because time is measured by motion (General Theory of Relativity) and motion could not exist, time would have ended. This theory can only hold true, however, if the universe could reach a state of maximal entropy. Most scientists do not believe this will happen, and that the universe will expand indefinitely.
Good Resources
http://www.thekeyboard.org.uk/What%20is%20Time.htm
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970613d.html
http://en.wikipedia.org/wiki/End_of_Time
http://www.hawking.org.uk/lectures/bot.html
http://www.guardian.co.uk/science/2008/apr/26/starsgalaxiesandplanets.universe3
http://en.wikipedia.org/wiki/Time (the sites used as sources are often more helpful than the actual article)
Potential Discussion Questions
1- What is time?
2- Does time have a beginning/end?
3- Does time exist in it's own dimension?
4- How does this relate to time travel possibilities, or impossibilities?
5- Should our ideas on time's existence be based around the big bang theory?
6- Is time relative, absolute or universal? (or a combination of the three)
:shifty Alrighty then, discuss!
Isaac Newton defined time as a container, and along with space, all events occurred within that container. His beliefs were based around the concept of absolute time and space, meaning that time is moving at the same rate for everything in the universe, or can be scaled for everything in the universe.
Albert Einstein revised the theory of absolute time, and proposed the theory of special relativity, and then later revised this theory to form The General theory of Relativity. [Wikipedia article] In simple terms, this theory states that time is measured by motion. It states that time can be effected by things such as gravity, and the motion of objects. It also states that time is a fourth dimension, meaning that in our three dimensional world we cannot "see" time. The best way to visualize the concept of another dimension is to think about an apple sitting in a bowl. If someone asked you where it was, you could say how far forward the apple was, or how far to the left, but you could only describe where the apple is now, not where it will be tomorrow or the next day, because those measurements exist in a different dimension. This also implies that the past, present and future exist equally within that dimension.
This theory is the most widely accepted, and most new theories or ideas about time are based upon this theory.
Beginning of time
Time, according to the big bang theory, began 15(some sources say 10) billion years ago. Time began with the formation of the universe. This is explained by the fact that, before the big bang, all of the matter in what would be the universe was compressed into one unit (technical term: a singularity). For the sake of understanding this concept, you can think of it as a small box. (understand that it has no volume or any real measurements). This box has an infinite density. this means that all of the laws of physics cannot apply to this pre-universe box. Because scientific laws don't apply to this pre-universe box, anything that happened to this pre-universe box isn't measurable by the standards that apply to our universe. Therefore, it cannot be on the same time frame as our universe, because the laws of our universe do not apply to the pre-universe box. Time had to begin with the big bang.
Note- That was only a visualization to understand the concept. The matter of the universe was not literally compressed into anything remotely similar to a box.
There are other theories and ideas about the beginning of time (or the lack of a beginning), however I just explained the most common theory. Some theories deny that a singularity ever existed; thus making time infinite.
End of Time
Time as we know it can only exist within the confines of our universe, according to the big bang theory, which is why time began with the big bang. This would also imply that time could end with the end of the universe. One such explanation for this is known as the theory of Heat Death. This theory states that it's possible for the universe to reach a frozen state, in which energy is non existent to sustain motion or life. Because time is measured by motion (General Theory of Relativity) and motion could not exist, time would have ended. This theory can only hold true, however, if the universe could reach a state of maximal entropy. Most scientists do not believe this will happen, and that the universe will expand indefinitely.
Good Resources
http://www.thekeyboard.org.uk/What%20is%20Time.htm
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970613d.html
http://en.wikipedia.org/wiki/End_of_Time
http://www.hawking.org.uk/lectures/bot.html
http://www.guardian.co.uk/science/2008/apr/26/starsgalaxiesandplanets.universe3
http://en.wikipedia.org/wiki/Time (the sites used as sources are often more helpful than the actual article)
Potential Discussion Questions
1- What is time?
2- Does time have a beginning/end?
3- Does time exist in it's own dimension?
4- How does this relate to time travel possibilities, or impossibilities?
5- Should our ideas on time's existence be based around the big bang theory?
6- Is time relative, absolute or universal? (or a combination of the three)
:shifty Alrighty then, discuss!
June 3rd, 2008 at 07:34am