# Space, Time & Mass: Exploring the Universe

• Shakes
In summary, the universe is 13.75 ± 0.11 billion years old, and we can calculate its age by looking at how fast different galaxies are moving away from us. If the pace of time is not always the same, we can messure time regardless to mass and speed by using cosmological time.)
Shakes
Hi Guys :)

Im no scientist or such, just a normal person pondering about stuff so go easy on me.

I lernt that if we look deep into space we are looking into the past. by looking at distant galaxies we can tell how old they are by looking at their stage in development. I guess that's how we can tell how old the universe is. (13.75 ± 0.11 billion years)

now I lert that time itself ticks differently depending how fast you move and where you are. Or should I say the mass of an objeckt near you.

So now I am wondering if I was at a very early point in time where the Univers still is a baby. the density of the universe is so great with such a huge mass that time should tick slower. or not?
on the otherhand the mass probably has't changed. but at that time all the mass was in one place.

If this is true and time moved slower at that time how would we feel it? Would I be able to watch the clock tick verry slowly or would'nt I notice anything? And if time did move slower at that time how can we say for sure that the universe is 13.75 ± 0.11 billion years old? Wouldent the universe be older than we think?

one more thing. If the pace of time is'nt always the same, how can we messure time regardless to speed and mass?

Please excuse my spelling. I'm not english :)

Astronomy news on Phys.org
Shakes said:
I lernt that if we look deep into space we are looking into the past. by looking at distant galaxies we can tell how old they are by looking at their stage in development. I guess that's how we can tell how old the universe is. (13.75 ± 0.11 billion years)
Light travels at a finite speed, so the light we see from other stars left them some time ago. The light from further away stars has been traveling to get to us for a longer time, so we are seeing an image of them from a longer time ago.
Also, we can tell how old the universe is by seeing how fast other galaxies are moving away from us, and approximating the time at which everything was in the same place. (In big bang theory, we assume the universe was initially very small, then expanded).

Shakes said:
one more thing. If the pace of time is'nt always the same, how can we messure time regardless to speed and mass?
We talk about cosmological time when we talk about the evolution of the universe, which means that at a particular cosmological time, the universe is at a particular stage in its evolution. Therefore cosmological time is independent of the masses, or velocities of observers.
Also, the universe was greater density in the past, but we wouldn't 'feel' time ticking differently. Just like someone in the gravity of a planet doesn't feel time ticking slower. Every observer feels like their own time ticks normally and that clocks in other reference frames tick different to normal.

Yes light travels at a finite speed, but if it passes a large mass its path bends. so it would take longer to get to its destination as if did'nt pass any mass object at all. so say light was to move a distance x at a time where the universe was verry small, wouldn't it have a longer path due to the huge mass as it would now moving the same distance? I can imagen that there was more matter in a spot in the early universe as there is now resulting to a larger mass. or not?

When the universe was very small, matter and radiation were coupled. This means that radiation was absorbed and emitted all the time. So when the universe was very small, light was not able to free stream in the way it does today. That is why we say the early universe was opaque (because you wouldn't have been able to see anything). (Of course, humans wouldn't have been able to exist in the very early universe, so you wouldn't survive, let alone see anything).
As the universe went on, radiation and matter decoupled, and the first few photons that existed in the transparent universe started free-streaming, and can now be seen as the cosmic microwave background radiation.
After this, the universe was more dense than it was now, but there was no large structures like stars or galaxies. The galaxies formed sometime after this, and the universe kept expanding and the average density kept getting less.
Scientists only used light sources from relatively close galaxies to calculate their speed relative to us. Therefore, the density of the universe was pretty much the same as it is now when the light was made that they use to calculate age of universe.
(In other words, they didn't use light from the beginning of the universe to calculate the age of the universe).

Hello,

First of all, I want to commend you for your curiosity and interest in the universe. It's always exciting to see people asking questions and trying to understand the world around us.

To address your first point about looking deep into space and seeing the past, this is indeed true. The light from distant galaxies takes time to reach us, so when we observe them, we are seeing them as they were in the past. This is similar to how we see stars in our own galaxy - the light from them takes time to reach us, so we are seeing them as they were in the past.

In regards to your second point about time ticking differently depending on speed and mass, this is known as time dilation and is a consequence of Einstein's theory of relativity. Essentially, the faster an object moves or the closer it is to a massive object, the slower time will appear to pass for that object. This has been observed and measured in experiments and is a well-established phenomenon in physics.

To answer your question about how we would feel time moving slower in the early universe, the answer is that we wouldn't feel it. Time dilation is a very subtle effect and would not be noticeable to us on a human scale. It is only when objects are moving at very high speeds or are extremely massive that we can observe significant time dilation.

As for how we can measure time regardless of speed and mass, we have developed tools and techniques to account for time dilation and make accurate measurements. For example, we use atomic clocks for precise timekeeping, which are not affected by speed or mass.

Finally, in regards to the age of the universe, our current estimate of 13.75 ± 0.11 billion years takes into account the effects of time dilation. Scientists have used various methods, such as measuring the cosmic microwave background radiation, to arrive at this age. While it is possible that the universe may be slightly older than our current estimate, the margin of error is small and does not significantly impact our understanding of the universe and its development.

## 1. What is the relationship between space, time, and mass?

The relationship between space, time, and mass is described by Einstein's theory of general relativity. This states that space and time are interwoven and form a fabric known as spacetime, and that mass and energy can curve this fabric, causing objects to move in a curved path.

## 2. How does the concept of spacetime affect our understanding of the universe?

The concept of spacetime allows us to understand how objects move and interact in the universe. It also helps us to understand the effects of gravity and the expansion of the universe. Without this understanding, many phenomena in the universe would be difficult to explain.

## 3. What is the role of mass in shaping the universe?

Mass plays a crucial role in shaping the universe. As mentioned earlier, mass can curve spacetime, causing objects to move in a curved path. This helps to explain the orbits of planets around stars and the formation of galaxies. Mass also determines the strength of gravitational forces, which influence the movement and interactions of objects in the universe.

## 4. Can we travel through time?

While there are theories that suggest time travel may be possible, it is currently not possible with our current technology and understanding of the universe. However, the concept of spacetime suggests that time is not a fixed entity and can be affected by factors such as gravity. This means that time can pass at different rates for different objects or in different parts of the universe.

## 5. How does exploring space help us understand the concept of time?

Exploring space allows us to observe and study objects and events that are billions of years old. By studying these distant objects, we can gain a better understanding of how time has passed and how the universe has changed over time. Additionally, space exploration has led to advancements in technologies such as atomic clocks, which have greatly improved our ability to measure time accurately.

• Astronomy and Astrophysics
Replies
24
Views
2K
• Astronomy and Astrophysics
Replies
7
Views
693
• Astronomy and Astrophysics
Replies
1
Views
1K
• Astronomy and Astrophysics
Replies
6
Views
2K
• Special and General Relativity
Replies
4
Views
830
• Cosmology
Replies
7
Views
1K
• Special and General Relativity
Replies
13
Views
486
• Astronomy and Astrophysics
Replies
3
Views
2K
• Special and General Relativity
Replies
25
Views
3K
• Astronomy and Astrophysics
Replies
1
Views
1K