ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Why Humans Will Never See the Edge of the Universe

Updated on February 22, 2014

You can think of the edge of the universe

Mind experiments that we can do

Suppose we want to take a look at the edge of the universe.How should we do it? Let’s try by means of mind experiment.

A mind experiment is one that cannot be done by physical experiments involving materials and methods. If you want to find the weight of a stone, you may use a weighing scale and take the weight of the stone, according the Newton’s theory of gravity. You use a material (stone) and method (weighing).

Mind experiment is different. Albert Einstein related one of his mind experiments. He wanted to know what would happen if he traveled with light that travels about 300,000 km per second. He concluded by means of reasoning that: his body would contract and his time would stand still. That is, his time clock would register zero. The mass of his body would increase.

Einstein could not do a physical experiment because there is no spacecraft yet that can travel as fast as light.

A mind experiment sometimes does not accomplish what we want. However, it explains why we cannot attain what we want.

First, assume that the universe started with the Big Bang about 5 billion years ago. (I have a Hub "Big Bang Theory, Origin of the Universe: What Is the Mystery?) We are not going to prove this assumption in this mind experiment. It is a starting point. Einstein did such a thing with his theories, special theory of relativity and generalized theory of relativity. He made as an assumption the Lorentz transformation. For one, Lorentz transformation says that the laws of nature in one coordinating system (for example, galaxy) are the same as in another coordinating system. He did not prove this by physical experiment. Besides he could not because there was no spacecraft that could take him to another galaxy. Even up to now that spacecraft is still unavailable.

We use light as the tracing element. This is the only one available in real life. Besides, as we know nothing else travels faster than light. That one indicated by c2 (speed of light squared) in the formula E = mc2 does not show one direction. It is rather the speed of light particles (photons) bumping into each other. (One result is splitting of an atom into two, a chain reaction in a nuclear bomb.)

We use a powerful telescope. Let us say we can make a telescope more powerful than the Hubble telescope. But no matter the power of the telescope its power will be limited by the speed of light in one direction.

Our method of physical experiment is peeping into our powerful telescope pointed toward the edge of the universe. Can we see the edge of the universe?

Let us add more considerations. The universe is finite. So, it must have an edge. However, the universe is expanding according to the generalized theory of relativity. Let’s say that the expansion is such that a point in the edge of the universe is moving away as fast as light.

Our mind experiment will show that we cannot see the edge of the universe. Why?

Our tracer is light. If we start the physical experiment now, our tracer is way, way behind the edge of the universe that started with the Big Bang billions of years ago. Our tracer, because it is light, cannot catch up with a point in the edge of the universe. That point had a head start of at least four billion lightyears. (A lightyear is the distance traveled by light in one year.) At one point in time, our tracer is at one point and the edge of the universe is also at another point. There is a wide gap between these two points. That gap will never be reduced.

But how did Einstein arrive at the prediction that the universe is expanding and that it is finite? It is by means of deductive logic that is part of mind experiment. His mind experiment (generalized hypothesis on relativity) was couched in mathematics. But his mind experiment could only be proven valid because the test of mathematics is validity. How could his mind experiment be proven as true? The test of a statement is truth (Russell, B. Human Knowledge: Its Scope and Limits. 1947). Russell was a mathematician and philosopher; a Nobel prize winner in literature (philosophy).

So, Einstein derived statements of facts from his mind experiment. These statements were in the form of predictions amenable to verification by physical experiment.

The prediction that the universe is expanding was proven by Edwin Hubble, an astronomer. That is one proof of the generalized hypothesis of relativity. Another prediction was that light bends in the vicinity of a great mass. This was verified by Sir Arthur Eddington in 1919. A hypothesis that is proven true graduates into a theory. Therefore, Einstein's generalized hypothesis of relativity graduated into the generalized theory of relativity.

Suppose we have a spacecraft that travels as fast as light and we would like to see the expansion of the universe. One thing to consider is that we should have a fuel that can jettison our spacecraft and leave the space-time of our galaxy.

This universe is composed of several galaxies (Levy, D. Cosmology 101.2003); some of them are even larger than our own. We may be able to leave the gravity of our galaxy but encounter another that of a larger galaxy. So, our spacecraft will free fall around that bigger galaxy. Free fall means that our spacecraft will travel in a hyperbola and will not impact on that bigger galaxy. A free falling spacecraft does not need fuel for its travel. The trajectory of our spacecraft will only match the curvature of that bigger galaxy. It is unlike an apple that when thrown upwards will impact (fall) on earth (Swinerd. How Spacecraft Fly. 2008).

Even if we prolong our travel, we will only be circling the bigger galaxy. In reality we cannot proceed to see the expansion of the universe. Then how did Hubble find out that the universe is expanding?. He derived it from the red shift.

Today, we don’t have a powerful fuel that can jettison our spacecraft beyond our galaxy. The satellites that had gone to Mars are still within our galaxy. Granting that we have that fuel, our spacecraft will circle around a bigger galaxy owing to the latter's gravity.

In the generalized theory of relativity, gravity is a curvature of space-time. It is not a force (as measured by weight) according to Newton's theory. That is why, even if the spacecraft is weightless, it still behaves following Einstein's theory of gravity.

Suppose reaching the edge of the universe is possible. We will not know that we are at the edge because our spacecraft will be circling around the universe in a free fall. This last statement belongs in probability that cannot be verified today or in the long future. It belongs in the law of excluded middle (Russell, B. Human Knowledge: Its Scope and Limits. 1947). The reason is that there is no evidence in its favor or against it. It is a statement that is neither true nor false. It is not knowledge.

Other tracer elements can be used like neutrino that is said to travel faster than light. This claim of neutrino's speed is still doubtful though. We can use the cosmic microwave background radiation (CMBR) that was discovered by Arno Penzias and Robert W. Wilson in 1965. CMBR is supposed to be the debris of the Big Bang. Therefore, it is traveling as fast as the edge of the universe. CMBR is similar to light in that there is a gap between our tracer CMBR and the edge of the universe. The tracer CMBR cannot catch up with the edge of the universe.

There are mind experiments that we can do that we cannot do by means of physical experiments.


Submit a Comment

  • conradofontanilla profile imageAUTHOR


    5 years ago from Philippines

    Your hand will be outside the universe. That is a possibility. Of course, we recall that "possibility" is anything we can think of. "Probability" deals with the real world. In real world you will not know whether you are just an inch away from the edge or not because you might be just circling along the gravity of a big galaxy. In Newtons' theory we thought we can extend a railroad track outside the edge of the universe. In real world the longest railroad track will end at our feet if it started there. Enjoy your mind experiments!

  • PDXBuys profile image


    5 years ago from Oregon

    Just as a thought experiment, let's say I had a 13.77 billion year head start... Travelling at the speed of light, just an inch behind the "wave front" (the expanding edge of the universe). Now I stick my arm out in front of me so that it extends about two feet. My hand is now beyond the edge. Where does my hand go? I will let you ponder that one! I enjoyed reading your hub - have been contemplating this for the last few months...

  • Kosmo profile image

    Kelley Marks 

    5 years ago from California

    There's lots of very good information here. I always love to read about Einstein's theories; Stephen Hawking has lots to say as well. Anyway, perhaps one day we'll be able to detect what is beyond the event horizon, and let's hope we like what we see. Later!


This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

Show Details
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)