# Why does time stop in the event horizon of a blackhole?

• Manraj singh
In summary: If the clocks on both sides of the experiment are synchronized, then the light from the "upstairs" clocks will be shifted to the "downstairs" clocks by the gravitational time dilation. From that experiment, you can measure the amount of redshift and calculate the strength of the gravitational field.
Manraj singh
Why does time stop in the event horizon of a black hole? Or at least slow down, from what i know.

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It depends on the reference frame. Something falling in experiences no effect on time. However a distant observer would see the object as slowing down and never quite falling in.

The explnation is in the equations of General Relativity. (I am no expert).

leonard susskind describes it pretty good on youtube classic mechanics lectures from stanford university really learned a lot from his lecture heavy into math if you ask me but he says it elementary math

Mr Marcus, the link given by you helped a lot. Please correct me if I am wrong: time does not actually decrease, but it appears to be slowed down due to red shift or blue shift.Sent from my iPad using Physics Forums

Manraj singh said:
Mr Marcus, the link given by you helped a lot. Please correct me if I am wrong: time does not actually decrease, but it appears to be slowed down due to red shift or blue shift.Sent from my iPad using Physics Forums

Time dilation really does occur, it's not just a result of red shift.

Manraj singh said:
Mr Marcus, the link given by you helped a lot. Please correct me if I am wrong: time does not actually decrease, but it appears to be slowed down due to red shift or blue shift.
...

I think people can have different perspectives on appearance vs. reality, Manraj.

Personally I consider gravitational time dilation to be absolutely real! And I consider it to be the same phenomenon as gravitational redshift.

Deeper down clocks run slower, the evolution of physical states is slower, the atoms in the downstairs laser vibrate slower, so the light it makes is redder---all from the standpoint of the guy upstairs.

The gravitational time dilation is what CAUSES the gravitational redshift. So both are actually real. That is just how I see it. Other people may have different ways to understand it.

I can see no other explanation for the gravitational redshift. Can you?

I think the way they experimentally TEST these gravitational effects is by sending light (or other electromagnetic signals) back and forth between "upstairs" and "downstairs" atomic clocks and other devices.

## 1. Why does time stop in the event horizon of a blackhole?

Time appears to stop in the event horizon of a blackhole because the gravitational pull becomes so strong that it warps the fabric of space-time. This means that time becomes distorted and slows down, eventually appearing to stop altogether.

## 2. How does the gravitational pull of a blackhole affect time?

The gravitational pull of a blackhole is incredibly strong, which means that it bends the fabric of space-time. This creates a steep slope in the fabric of space-time, causing time to slow down and eventually stop in the event horizon.

## 3. Can time really stop in the event horizon of a blackhole?

From our perspective, time appears to stop in the event horizon of a blackhole. However, for an observer falling into the blackhole, time would continue to pass normally. This is due to the intense gravitational forces altering our perception of time.

## 4. What happens to time inside a blackhole?

Inside a blackhole, the fabric of space-time becomes so warped that time no longer follows a linear path. Instead, it curves in on itself, making it impossible to determine what happens to time inside a blackhole.

## 5. Is time the only thing that stops in the event horizon of a blackhole?

No, other physical laws and properties, such as light and matter, also behave differently in the event horizon of a blackhole. This is because the intense gravitational pull distorts the fabric of space-time, affecting all aspects of the universe.

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